Doping-induced magnetic phase transition enables all-electrical spin control in CrSBr

Domain: physics
Published: 2025-12-19
Editorial outcome: major_revision

Abstract
VanderWaalsantiferromagneticsemiconductorsarepromisingplatformsforenergy-efficienttwo-dimensionalspintronics.However,theirintrinsicspindegeneracyandthedifficultyofachievingelectricalspincontrolposemajorchallengesforpracticaldeviceimplementation.Here,wepresentadistinctspintronicplatformbasedonanantiferromagneticsemiconductorCrSBr,inwhichcarrierdopinginducedbygate-controlledintercalationdrivesareversible,zero-fieldantiferromagnetictoferromagneticphasetransition,enablingdirectandfullelectricalcontrolofbothmagneticorderandspinpolarization.Exploitingthistransition,weengineerCrSBr/grapheneheterostructuresthatleverageinterfacialchargetransfertospatiallypatternmagneticphases,resultinginlateralspinvalveswithgate-controlledspinpolarizationreversal,allwithoutferromagneticcontacts.Crucially,thismechanismalsoenableselectricalswitchingofmagneticorderviaspin-transfertorqueatultralowcurrentdensities(<103A/cm2),demonstratingitsefficiencyanddevicecompatibility.Thesefindingsopenanewparadigmforreconfigurable,all-electricalspintronicsystemsbasedonvanderWaalsantiferromagneticsemiconductors.

Introduction
Thepursuitofelectricalcontrolovermagneticorderandspinpolarizationinquantummaterialsstandsattheforefrontofcondensedmatterphysics,offeringapathwaytoenergy-efficientspintronicdevicesforinformationstorageandprocessing1–4.LayeredvanderWaals(vdW)magnetshaverecentlyemergedasahighlypromisingplatformduetotheirgate-tunablemagneticstatesandtailorableinterlayerinteractions5–12.Amongthem,A-typecollinearantiferromagnetsareofparticularinterestfortheiruniquecombinationofintralayerferromagnetismandinterlayerantiferromagnetic(AFM)coupling,whichresultsinlayer-lockedspin-polarizedbandswithzeronetmagnetization13–15.Recentworkhasdemonstratedthatelectric-field-inducedsymmetrybreakingineven-layerCrPS4canspin-polarizeconductionbands13,14,althoughthismethodpreservestheinterlayerAFMorder.AmoreeffectiveformofspincontrolinvolvesdirectlymanipulatingthecouplingbetweenlayerstodriveaninterlayerAFM-to-ferromagnetic(FM)transition,wherethephasechangecandrasticallyaltertheglobalmagneticstate.However,realizingsuchdeterministicspincontrolatzeromagneticfieldviatheAFM-to-FMtransitionremainsexperimentallychallenging9–11,16–18.

Carrierdopingoffersapowerfulalternativefortuningmagnetismandunlockingemergentquantumstates,asillustratedincolossalmagnetoresistance(MR)systems19andhigh-temperaturesuperconductors20.Electricalcontrolofcarrierconcentration,inparticular,hasbeenimplementedtomodulatemagneticorder8viaspin-chargecouplingcontrolledbygating.AvdWsemiconductorCrSBr(SupplementaryNote1andFig.S1),showingA-typeAFMorder(Fig.1a),canhostmoredramaticdopingresponses:duetoitsweakinterlayercouplingandstrongcharge-spincorrelations16,21,22,dopingCrSBrcandirectlyinducebothmagneticorderingandspinpolarization.TheoreticalcalculationsrevealastarkcontrastbetweenAFMandFMconfigurationsinitsspin-resolveddensityofstates(DOS)(Fig.1a,b):theAFMstateexhibitspindegeneracy(netpolarizationP=0),whereastheFMphaseshowsnear-completespinpolarizationattheconductionandvalencebandedges.Crucially,calculationsoftheAFM-FMenergydifference(Fig.1candSupplementaryFig.S2)demonstratethatcarrierdopingstabilizestheFMstateatexperimentallyaccessibledensities(1012~1014cm2),aligningwithpreviouspredictions21,thusestablishingcarrierdopingasaneffectivemechanismformodulatinginterlayermagneticorderandspinpolarization.

Guidedbytheseinsights,wedemonstrateinsituelectricalcontrolofbothmagneticorderandspinpolarizationinCrSBratzeroexternalmagneticfield.First,weuseionicgatingtodriveareversibleAFM-to-FMtransition,manifestedindistincthystereticMRsignatures.Second,leveraginglocalinterfacialchargetransferfromgraphene(Gr)contacts,wespatiallymodulatethemagneticordertoformalateralspin-valveconfigurationwithgate-tunablespinpolarization(Fig.1d).Finally,weachieveelectricalmodulationofmagneticorderinthelateralCrSBrchannelviaspin-transfertorque(STT)atultralowcurrentdensities.TheseresultstogetherestablishCrSBrasaversatileplatformforall-electricalspintronics,enablingintegratedcontrolofmagnetismandspinswithoutrelyingonFMcontacts23–26.

Results
Zero-fieldmagneticphasetransitiondrivenbygate-controlledcarrierdoping
CrSBrisanair-stableA-typevdWAFMsemiconductorwithabandgapof~1.5eV27,28andahighNeeltemperatureT of~132K22,29,30.ItexhibitsintralayerFMorderingandAFMinterlayercoupling,withtheeasyaxisorientedalongtheb-direction(Fig.1a)22,27,31.PreviousattemptstomodulatemagnetisminCrSBrusingconventionalsoliddielectricshaveinducedonlymodestchangesinthecoercivefieldofthinflakes16,whileeffectivegatecontrolinthickerflakesremainsevenmorechallenging.Morerecently,chemicallithiumintercalationhasbeenshowntoinduceanAFM-to-FMphasetransitioninbulkCrSBr32,highlightingthecriticalroleofcarrierdopingintuningitsmagneticgroundstate.Here,weemployanelectricallycontrolledionic-liquidgatingapproachthatenablesreversible,high-densitycarrieraccumulationandcontinuouscontrolofthemagneticphasetransitioninCrSBrflakes,allowingsystematicmappingofthephasediagramunderelectrostaticmodulation.

AsillustratedinFig.2a,wefirstusedLiClO /PEOelectrolyteastheionicmediuminourdevice(seeMethods).Thelithiumintercalationwascontrolledbyaliquid-gatevoltage(V )toenableglobalcarrierdoping,monitoredviaroom-temperatureconductancemeasurementsonathickCrSBrdevice(~ 6nm, Sample D1). At V =6V, the conductivityincreasesbyoveranorderofmagnitude(Fig.2b).PristineCrSBrexhibitssemiconductingbehavior,withconductancedecreasinguponcoolingandshowingalocalmaximumnear132KatV =0V(Fig.2c).ThismaximumcoincideswiththeonsetofAFMorderingandisattributedtotheassociatedsuppressionofspin-disorderscattering22. Upon intercalation doping (V =6V), the conductance maximum shifts to ~207K, in consistent with earlier report32. InFM semiconductors, T typically lies slightly above the conductance maximum33,34, asseen for monolayer CrSBr22. These results indicate thatgate-controlledintercalationdopingenableseffectivetuningofthemagneticphaseandalsoincreasesthemagneticorderingtemperatures.

Tofurtherverifythismagnetictransition,weperformedtheMRmeasurementswiththeexternalmagneticfield(B)sweepingalongtheeasyaxis(b-direction)atdifferentliquid-gatevoltagesandtemperatures.ThesystematicevolutionofMRisprovidedinSupplementaryFig.S3.WedefinetherelativeMRasMR%= R(B)-R(0T) / R(0T) * 100%.AsshowninFig.2d,theMRatV =0Vprimarilydecreasessharplyatacoercivefieldof~ 0.4T,consistentwithafield-inducedFMtransitionsuperimposedonanAFMgroundstate,whereantiparallelinterlayerspinssuppresselectronhopping.Incontrast,followingintercalationat6V,theAFMsignaturevanishes,andtheMRexhibitsabutterfly-shapedhysteresiswithzero-fieldresistancematchingthatat1T,indicatingtheformationofastableFMgroundstatewiththemagneticeasyaxispreservedalongb-direction21,32.ThesechangesunderscorethestrongsensitivityofMRtotheunderlyingmagneticstructure22,31,35.Thegate-dependentMRfeaturesthusprovidedirectevidenceforanAFM-to-FMtransitiondrivenbyintercalation-inducedcarrierdoping.Duetothein-planespinorientationandpronouncedtransportanisotropyinCrSBr,directHallmeasurementstoextractmagnetizationwerenotfeasible27,29,30.Instead,asshowninFig.2e,micromagneticsimulationsfittedtoourMRdata(alsoseeSupplementaryNote2andSupplementaryFig.S4)confirmtheAFMandFMbehaviors.Furthermore,temperature-dependentMRdifferencemeasurements(definedasΔMR=MR forward% - MR backward%)revealdistinctthermalevolutionsofthecoercivefield(B)andanenhancedcriticaltemperature(T )fortheAFMandFMstates(Fig.2f).Asthemagnitudeofinterlayerexchangecouplingissmallerthanintralayeronesbyabouttwoordersofmagnitude(seeSupplementaryNote3andSupplementaryTableS2),thisincreaseinT primarilyarisesfromelectron-doping-enhancedintralayereffectiveexchangeinteractionsinCrSBrassupportedbyourfirst-principlescalculations(SupplementaryFigs.S5,S6),underscoringtheeffectivethermalstabilizationofFMorderthroughcarrierdoping32.

Localmagneticordermodulationandgate-controlledspin-valvebehavior
HavingconfirmedcarrierdopingasthemechanismformodulatingthemagneticorderinCrSBr,wenextemploythelocal-dopingstrategythatexploitsinterfacialchargetransferfromgraphenetospatiallymodulatethemagneticorderofpristineCrSBr.Thisapproachenablesspininjectionanddetectionthroughseparateddoping-inducedFMregionsandtheresultingspin-filteringeffect.Figure3a,bshowtheschematicandopticalimageofourCrSBr/Grheterostructuredevice(SampleD2),wheretwographenestripesserveaselectrodesandtheglobalback-gatevoltageV isappliedtothedopedSisubstrate.TheCrSBrflakeisidentifiedasatrilayerbasedonopticalcontrastandatomicforcemicroscopy(Methods, Supplementary Fig. S1), with a channellengthof~1μmalongthea-axis.TheoreticalstudiespredictstrongchargetransferattheCrSBr/Grinterface,leadingtoeffectiveelectrondopingcapableofinducinganAFM-to-FMtransitioninthin-layerCrSBr21(alsoseeFig.1c).Toverifythisinourdevice,wecomparedthetransfercurvesofpristinegraphenewithgrapheneincontactwithCrSBr,asshowninFig.3c.TheCrSBr/Grinterfaceinducesa73Vshiftingraphene’schargeneutralitypoint,correspondingtoalargechargetransferof~ 5.5×1012cm−2 (calculated from the 285nm SiO gate capacitance and typically required high quality interface between grapheneandCrSBr).ThissubstantialchargetransferissufficienttolocallyinduceFMorder21 at the two graphene-contacted regions, creatingalateralFM/AFM/FMconfigurationthatsupportsaspin-valveeffectforverifyingspinpolarizationmodulation.

Todemonstratetheresultingspin-valvebehavior,weperformedmagneto-transportmeasurementsat2K.Figure3dpresentstheMRdatameasuredusingtwographenecontactsunderabiasvoltageofV =0.48VandagatevoltageV =-40V.Duringthemagneticfieldsweeps,anMRtransitionappearsatacoercivefieldof~ ± 0.35T,labeled“AFMMR”,indicatingspinflippingintheCrSBrchannelfromanAFMtoanFMstate22,27,36.Withinthehigh-resistanceplateauoftheAFMordering,abruptdropsinresistanceoccurnear± 0.2T,dependingonthesweepdirection.Thesehystereticdropsarecharacteristicofspin-valvebehavior28,37(denotedas“spin-valveMR”)inourCrSBrdevicewithgraphenecontacts.IntheinsetofFig.3d,welabeldiscreteresistancestates“0”to“4”andillustratethecorrespondingmagneticstatesfortheforwardsweepofmagneticfield(redcurve).TheassociatedspinconfigurationsintheCrSBrlayersarediscussedinSupplementaryNote4andSupplementaryFig.S7.Wenotethatthespin-valvebehaviorisalsoreproduciblewhenthefieldsweepisconfinedwithin±0.3T(SupplementaryFig.S7b).Finally,controlexperimentsusingAu-AuandGr-Aucontacts(SupplementaryFig.S8)donotexhibitsimilarspin-valveMR,confirmingthattheobservedspin-valvebehaviorarisesintrinsicallyfromthelateralconfigurationcreatedbylocalchargetransferfromgraphene.MorediscussionisprovidedinSupplementaryNote5andFig.S9.

Moreimportantly,thisspin-valvebehaviorisfullygate-tunable,featuringasignreversalofthespin-valveMRthatconfirmselectricalcontrolofthespinpolarizationinourCrSBrdevice.WeperformedMRmeasurementsatdifferentgatevoltagesoveramagneticfieldsweepof±1T(SupplementaryFig.S10)andthecentral±0.3TwindowisshowninFig.3e.AtafixedV =0.48V,positivespin-valveMRisobservedatV =-90and-80V,followedbycompletesuppressionatacriticalgatebiasofV =-72V.AdjustingV acrossthecriticalpointrestoresthespin-valveMRwithareversedsignasV isincreasedfrom−90to80V.Similar gate tunability is observed at V =0.4V (Supplementary Fig.S11).InanotherCrSBrdevice(SampleD3)thatisencapsulatedwithhBNandequippedwithahigh-kdielectric,thegatetunabilityisfurtherenhanced,allowingthepositivespin-valveMRtobemodulatedfrom36% to nearly zerobyincreasing V from -2 to 0V (Supplementary Fig. S12). Such robust gate control represents a significant advance over the conventional spin-valve devices that rely on FM metal contacts24.

Gate-tunablespinpolarizationinCrSBr/Grheterostructure
Weattributethesignreversalofthespin-valveMRnearV =-72 V(Fig. 4a) to the gate-tunable spin polarization of the two CrSBr/Gr electrodesunderalargebias.Thespinpolarizationofeachelectrodeisdeterminedbythedistributionofspin-resolvedelectronicstateswithinthetransportenergywindowdefinedbyitslocal electrochemical potential. Under a finite bias V , these transport windowsareoffsetbetweenthetwocontactsandcanberigidlyshiftedtogetherbytheglobalgateV ,asillustratedinSupplementaryFig.S13.Whenthedominantspinspecieswithintherespectiveenergywindowsdiffer,thetwoelectrodesacquireoppositespinpolarization.AsillustratedinFig.4b,thenetspinpolarizationofeachCrSBr/GrelectrodethusdependsjointlyonV andV .WhenV <−72V,bothelectrodesexhibitpositivespinpolarization(leftpanelofFig.4b),resultinginalow-resistancestatefortheparallelalignmentoftheirmagnetizations(states “1” or “3”), and a high-resistance state for the antiparallel alignment(state“2”).OnceV exceedsthecriticalbias,theelectrodesacquireoppositespinpolarizations(rightpanelofFig.4b),invertingtheresistancestate.Consequently,thesignofthespin-valveMRisdeterminedbytheproductofthespinpolarizationoftwoelectrodes(P andP ),assumingthatspinpolarizationremainsunchangedduringspindiffusionthroughthechannel.

Tofurtherelucidatethisbehavior,wecalculatedthespinpolarizationPfortheCrSBr/Grheterostructureswithvariouslayerthicknessesusingdensityfunctionaltheory(Fig. 4c).The corresponding band structures for different CrSBr/Gr configurations are shown in SupplementaryNote6andSupplementaryFig.S14.ThesecalculationsrevealthatthespinpolarizationisnearlyinsensitivetothethicknessofgrapheneorCrSBr,highlightingitsrobustnessacrossawiderangeofdeviceparameters.Figure4dpresentsthecalculatedMR,whichscaleswith P P =P(E)[P(E+eV )+P(E-eV )]/2, where V = 0.48 V is theACbiasbetweenthetwoCrSBr/Grelectrodes,andEistheelectrochemicalpotentialofthedrain-sideCrSBr/Grelectrode.ThegatevoltagesimultaneouslyshiftstheFermilevelsofbothelectrodes,leadingtoasignreversalincalculatedMRwhentheFermilevelmovesto~0.28eV(dashedlineinFig.4d).Byestimatingthecarrierdensityingrapheneundertheseconditions,wefindexcellentquantitativeagreementwiththeexperimentaldata(Fig.3c),wherethespin-valveMRsignreversesatVG = - 72 V(SupplementaryNote 7). This result confirms that the gate modulation can fully reverse the spin polarization in our CrSBr spin-valve device, demonstratinglargetunability.

ElectricalmanipulationofmagneticorderthroughSTT
WealsoobserveapronouncedSTTeffectinthelateralCrSBrchannel,enabledbylargespin-polarizedcurrentinjectedthroughdoping-inducedFMcontactregions.STTtransfersspinangularmomentum,therebyalteringthemagneticorderoftheCrSBrchannel.Toconfirmthis,wemeasuredtheMRat2KoverarangeofV ,asshowninFig.5a.WithV =0V,thecurrentincreasesnonlinearlyfrom18to856nAasV israisedfrom0.2to0.51V,whilethespin-valveMRremainsnearlyconstant.Incontrast,theAFMMRgraduallydiminishesandeventuallyvanishesathigherV .Figure5bpresentstheevolutionoftheAFMandspin-valveMRwithV .TheoreticalcalculationsindicatethatthespinpolarizationofCrSBr/Grheterostructureremainsnearlyunchangedoverthisbiasrange(SupplementaryFig.S15).Hence,weattributethedisappearanceoftheAFMMRtotheincreasedspincurrentdensity,whichamplifiesthe STT in the channel and drives an AFM-to-FM magnetic order switching(Fig.5c).Asexpected,adjustingtheDCbiasvoltagecanalsomodulatethemagneticstateviaSTT,asconfirmedinSamplesD2(SupplementaryFig.S16)andD3(SupplementaryFig.S17).TovalidatethisSTTmechanism,weperformedcontrolexperimentsonCrSBrdeviceswithAuelectrodes(SupplementaryFig.S18).IncreasingthecurrentinthesedevicesdoesnotsuppresstheAFMMR,confirmingthattheSTTeffectisuniquetoourdeviceconfigurationwithgraphenecontacts. Such STT-driven magnetic order manipulation is rarely observedinlateralspin-transportdevicesusingtwo-dimensional(2D)magneticmaterialsorthinmagneticfilms38,39.

Weestimatethatthethresholdcurrentdensity(j )requiredtoinduceSTTinourdevicesislessthan103A/cm2(topaxisofFig.5b,alsoseeSupplementaryNote8andTableS1),whichismorethananorderofmagnitudelowerthanpreviouslyreportedspin-torquethresholdsinlateralstructures38,40.ThisreductionlikelystemsfromthecleanvdWinterfacesinourheterostructures,whichminimizepinningcentersrelativetoconventionalFM-metalinterfaces.Recentreportsoflayer-sharinglateralexchangebiaseffectinCrSBralsosupportourscenariooflowcurrentSTT41.

WefurtherexploredthetemperaturedependenceoftheMRatV =0.2VandV =0Vfrom2to150K(Fig.5d).TheAFMcoercivefielddecreasesasthetemperatureisincreased,andtheAFMMRpersistsupto~130K,consistentwithpreviousreports22,27,29,31.Incontrast, the spin-valve MR vanishes near 10K, presumably due to a reducedspindiffusionlengthatelevatedtemperatures.AsshowninFig. 5e, the AFM MR decreases whereas the coercive field remains unchanged with increasing V at 10K, confirming thatSTT effects persistatelevatedtemperaturesandrulingoutpurelythermalinfluences. Meanwhile, the emergence of positive MR in perpendicular fieldsandbutterfly-shapedMRsignalswithparallelfieldsathigherV (SupplementaryFig.S9candFig.S19)furthersupportsanSTT-inducedFMorder.Similarbutterfly-shapedMRsignalsalsoappearonthehigh-resistanceAFMplateauwhenthetemperatureexceeds10K(SupplementaryFig.S20),indicatingthecoexistenceofFMandAFMorder42in theCrSBr.Thistemperature-dependentspin-valveandMRbehaviorislikewiseobservedinafour-layerCrSBrdevicewithgrapheneelectrodes(SampleD4,SupplementaryFig.S21),underscoringtheversatilityandeffectivenessofourapproachforrealizinggate-tunablelateralspinvalveswithoutconventionalFMcontacts.

In summary, we demonstrate that carrier doping serves as an effectiveandversatilemechanismforcontrollingbothmagneticorderandspinpolarizationinasinglevdWantiferromagnet,CrSBr.Byleveragingthestrongcouplingbetweenchargedensityandinterlayerexchangeinteractions,weachieveadeterministicandreversibleAFM-to-FMphasetransitionatzeromagneticfield.ComplementaryapproachesofinterfacialchargetransferandSTTenablespatialanddynamicmodulationofmagneticstates,expandingthetunabilityofthissystem.Notably,werealizelateralspin-valveconfigurationswithgate-controlledspinpolarizationreversalandlargetunability,allwithoutrelyingonFMcontacts.Furthermore,thelowcurrentdensities(<103A/cm2)requiredforSTT-drivenswitchingpointtothepotentialforenergy-efficientspintronicoperation.Together,thesefindingshighlightCrSBrasapromisingmodelsystemforall-electricalspintronicdevices,integratingmultiplespinfunctionalitieswithinasinglegate-tunablematerial.

Methods
Samplegrowthanddevicefabrication
High-qualityCrSBrsinglecrystalsweresuccessfullysynthesizedviathechemicalvaportransfer(CVT) method,usinghigh-puritychromiummetalpowder,sublimatedsulfurpowder,andliquidbromineasprecursors.ThegrowthconditionsandstepsaredescribedindetailinSupplementaryNote1.Weusedapolydimethylsiloxane(PDMS)stamp-assistedmechanicalexfoliationtechniquetoprepareCrSBrthinflakesinair.Thelayernumberoftheflakeswasdeterminedbyheightprofilingusinganatomicforcemicroscopeandobservingopticalcontrastinopticalmicrographs(SupplementaryFig.S1).

CrSBrdeviceswithgraphenecontactswerefabricatedusingaPC-baseddry-transfertechnique43.Toensurehigh-quality,bubble-freeCrSBr/Grinterfaces,weadoptedanadditionalthermalexpansion-contractioncontrolstepduringthetransferprocess.ThePCfilmwasheatedto150°Cforadhesionandslowlycooledto60°Cforcontrolledrelease,whilerepeatedmildthermalcyclesduringthedrop-downprocesseliminatedtrappedbubbles.Finally,thePClayerwasdissolvedintrichloromethanetoobtainaclean,residue-freeinterface.TypicalCrSBrflakesareinaribbonshape,withlongandshortedgescorrespondingtotheaandbcrystalaxes,respectively.TheCrSBrthinflakeswerestackedontothegrapheneelectrodeson285nmSiO /Si substrates with long edges aligned vertically to the graphene stripes. Subsequently,Cr/Au(5/70nm)electrodesweredefinedandthermallyevaporatedontoCrSBrorgrapheneusingastandardelectron-beamlithographyprocess.

Electricaltransportmeasurements
TheionicmediumLiClO /PEOpolymerelectrolytewasappliedtothetopofthethinflakeandthesidegateelectrodeforionicgating.ThedeviceconfigurationisillustratedinFig.2a.LiClO andPEOpowders(0.3g and 1g, respectively) (PEO; M = 100,000) were mixed with 15mlanhydrousmethanol(AlfaAesar).Themixturewasthenstirredovernightwiththetemperaturekeptat50°C44.TheglobalintercalationdopingiscontrolledbyadjustingthegatevoltageanditsdopingeffectismonitoredbymeasuringtheconductivityoftheCrSBrdeviceatroomtemperature.

Low-temperature transport measurements down to 2K were performedinacommercialCryogenicSuperconductingMagnetSystem(1.6–300K,12T).Longitudinalresistancewasmeasuredinatwo-terminalconfiguration,usinganSR830lock-inamplifiercombinedwithanSR570currentamplifierforsourcingvoltageandmeasuringcurrentatareferencefrequencyof17.77Hz.ForDCmeasurements,aKeithley2636Awasusedtosourcevoltageandmeasurecurrent.Gate-dependentmeasurementswereconductedusingaKeithley2400toapplyvoltagestothegates.

Theoreticalcalculations
We performed density functional theory (DFT) calculations, implemented in the Vienna Ab initio Simulation Package (VASP)45, to determine the carrier-doping-dependent energy difference between collinearFMandAFMstatesofCrSBr,aswellastheelectronicstructureoftheCrSBr/Grheterostructures.Theprojector-augmentedwave(PAW)method46was employedtodescribetheinteractionbetweenions and electrons. The Perdew-Burke-Ernzerhof (PBE) functional within the generalized gradient approximation (GGA)47 was used to treattheexchange-correlationeffects.FurtherdetailsofthetheoreticalcalculationsareprovidedinSupplementaryNote5.WealsoverifiedthatincludingthevdWinteractionsproducesnegligiblechangesinthecalculatedresultspresentedhere.

The magnetic properties of CrSBr under carrier doping were systematicallyinvestigatedthroughacombinationofexperimentalmeasurements and computational modeling. Magnetization curves were reconstructed from MR data using established anisotropic magnetoresistance (AMR) and giant magnetoresistance (GMR) frameworks, providing a non-destructive approach to quantitatively tracktheevolutionofmagnetizationunderdifferentmagneticfields.Tocomplementourexperiments,weperformedMonteCarlosimulationsoftheCrSBrsystemusinganextendedHeisenbergHamiltonianthatincorporatesbothintralayerandinterlayerexchangeinteractions35.Theexperimentalandcomputationalresultsdemonstratedconsistentresultsofmagnetizationcurves.FurtherdetailsofthesetheoreticalcalculationsareprovidedinSupplementaryNote5andFig.S2.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "The work reports an observation of carrier-doped induced interlayer Antiferromagnetic to Ferromagnetic phase transition in\nCrSBr semiconductor. Although electrical control of magnetic phase transition is already studied in the CrSBr system, the\npresent work demonstrates the CrSBr/Graphene heterostructure-based lateral spin-valve without FM metal contact by\nexploiting the interlayer charge transfer caused doping effect induced AFM-FM phase transition. The authors have\nestablished the tunability of spin-valve magnetoresistance (MR) by pure electrical means and try to explain how electrical\nmeans tune the spin polarization. However, the manuscript has the following issues to be addressed. Without addressing\nthese issues, the manuscript is not suitable for publication in Nature Communications in its current form.\n“Local maximum near the T_N ~ 132 K in figure 2c is likely reflecting reduced scattering from spin fluctuations after AFM\nordering”. Authors should explain the correlation between the shift in the characteristic maximum and doping-induced\nmodulation of magnetic ordering more comprehensively.\nThe manuscript reported that the interlayer AFM coupling is transformed into interlayer FM coupling after doping. In the\nundoped system, CrSBr has an easy axis of magnetization. Is there any change in magnetic orientation after doping induced\nAFM-FM transition? This information should be provided, which is crucial for applications.\nMagnetic phase transition discussed in the manuscript is an interlayer AFM to FM transition. The intralayer magnetic\ncoupling is FM in the system. Regarding the lateral Spin valve device design, the channel will always have an intralayer\nferromagnetic coupling. Is it accurate to consider the channel to be completely antiferromagnetic, while the magnetic\nmoments are intralayer ferromagnetically coupled?\nWhy the spin-valve behavior is reproducible only when the field sweep is confined within ±0.3 T and not reproducible if the\nfield sweep is beyond ±0.3 T.\nBand structure of the system after doping is required to check whether the materials remain semiconducting after doping or\nnot. If the CrSBr does not remain semiconducting and become conducting after doping, then it will not be possible to locally\ndope the system to device a spin valve with spatially localized graphene contact.\nIn line 73, the mentioned A-type AFM order is not discussed in Supplementary Note 1 and there is no information about the\nmagnetic phase in Figure S1, as mentioned in the main text.\nIn line 97, the b direction should be more clearly stated in connection with the unit cell of CrSBr.\nIn Figure 1a and 1b, y axis for DOS structure should be (Energy)-(Fermi Energy)\nIn line 128, increase in T¬C is concluded to arise from electron-doping-enhanced intralayer effective exchange interactions\nin CrSBr. However, doping induced an interlayer AFM to FM phase change in the CrSBr, which indicates that doping has a\nprominent effect on the interlayer exchange coupling. The role of interlayer exchange coupling on the critical temperature\nshould also be investigated and discussed.\nIn line 142, figure 1e is referred in the main text, but there is no Figure 1e in the manuscript.\nIn line 182, it is mentioned that both electrodes exhibit positive spin polarization and after the critical bias, the two electrodes\nacquire opposite spin polarization. How the author evaluated and confirmed the similar or opposite spin polarization of the\ntwo electrodes need to be discussed. Further, the calculation of spin polarization of different heterostructures is not sufficient\nto interpret how the spin polarization of the two Graphene contacted electrodes are controlled by electrical means. Their\nclaim of gate tunable spin polarization reversibility is not established clearly.\nSome syntax error in Supplementary note 2.\nA more comprehensive discussion on confirmation of the STT effect driven magnetic phase transition in the device\nconfiguration with graphene contacts is required.\nDetails of the theoretical calculation of intralayer exchange coupling is required.", "reviewer_2": "Review of manuscript # NCOMMS-25-52126-T\nTitle: Doping-Induced Magnetic Phase Transition Enables All-Electrical Spin Control\nin CrSBr\nIn their manuscript Zhao et al. investigated doping by lithium intercalation and electrostatic gating (?) in few-layer CrSBr\ndevices with graphene (or Au) contacts by measuring MR and performing theoretical modelling (DFT, Monte Carlo, toy\nmodel for magnetization). They observe an AFM-to-FM phase transition by intercalation doping. They claim that the devices\nwith graphene contacts form lateral spin valves exhibiting spin transfer torque.\nI think that the manuscript is in principle interesting, however, lacks clarity and is difficult to follow for a slightly more general\naudience due to use of many buzz words and technical jargon that is not explained. I recommend reconsideration after major\nrevision and have the following comments:\n1. In the abstract, the authors write “in which carrier doping alone drives a reversible, zero-field AFM to ferromagnetic (FM) phase transition”. The authors should add that this is by intercalation doping, which is rather different from regular field effect\ndoping. Intercalation with lithium also changes interlayer spacing, which itself has a strong effect on magnetic order. There\nhave been prior studies on intercalation doping in CrSBr (i.e. ref. 33), where AFM-to-FM transitions have also been\ndemonstrated. What makes the results presented here novel?\n2. In the abstract, the authors write “tunability exceeding 100%”. What does that mean? They use this expression several\ntimes without explaining it. In line 260 they state “gate-controlled spin polarization exceeding 100%”. What’s a more than\n100% spin polarization? That does not make any sense to me.\n3. The authors refer to samples D15, D41, D66 and so on. Renaming their samples as 1, 2, 3, etc or some other more\nobvious nomenclature would help with readability.\n4. In line 97 onward, the authors write “Previous attempts at gate control using conventional solid dielectrics have induced\nonly modest changes in the coercive field in thin CrSBr flakes… we employ ionic gating to accumulate higher carrier density\nin inducing magnetic phase transition in CrSBr”, which sounds like they are doing something particularly novel here.\nHowever, as mentioned above lithium intercalation doping has already been achieved (i.e. ref. 33), even going to\nsignificantly higher doping densities. This text should be rephrased to better place the manuscript within the state of the art.\n5. In line 141 onward, the authors write “Theoretical studies predict strong charge transfer at CrSBr/Gr interface that can\ninduce an AFM-to-FM transition in thin-layer CrSBr” referencing two articles. I noticed that this statement is not supported by\nthe cited ref. 16, which does not make any theoretical predictions about charge transfer at CrSBr/Gr interfaces.\n6. In line 142 the authors write “(also see Fig. 1e)”, however, there is no Fig. 1e in their manuscript.\n7. From line 152 onwards, the authors refer to a gate voltage VG, which is not previously defined and not indicated in any\nsample illustrations. Are the authors referring to some undefined global back gate? The authors should clarify their structure\nand explicitly state what they are doing. VG should appear in a sample illustration. Do I understand correctly that from line\n133 onward the authors are no longer using ionic gating but regular electrostatic gating?\n8. Do I understand the authors correctly that they are claiming that CrSBr in contact with graphene is always in a FM state?\nIf yes, I must disagree. See for example ref. 16 (supplementary Fig. 7). Contact to graphene does not just change the magnetic\norder in CrSBr. Under certain conditions, probably.\n9. Could it be that the state “2” the authors observe in Fig. 3c is simply a sign of layer-by-layer spin flip transitioning from one\nAFM order to the other via an intermediate state? This is what it reminds me of. The 0.2 T at which it occurs matches well\nwith the critical field of the bilayer. See for example Ref. 16 (Fig. 3, optical study of trilayer) as well as Liu et al., Phys. Rev. B\n111, L140417, where they show the MR for different layer numbers with the layer-by-layer spin flips inducing changes in the\nMR. Have the authors studied a bilayer CrSBr device? This could give clear evidence of the mechanism, as it cannot show\nthis layer-by-layer switching but would presumably show the spin valve behavior."}, "author_response": "Point-by-Point Response to Reviewers’ Comments\nWe sincerely thank the Reviewers for their detailed and insightful comments. Their\nconstructive feedback has been invaluable in improving the clarity, depth, and overall\nquality of our manuscript. In response, we have performed additional experiments,\nexpanded the theoretical analysis, and thoroughly revised the manuscript and\nSupplementary Information accordingly. We believe that these revisions have\nsignificantly enhanced our manuscript. Below, we provide detailed, point-by-point\nresponses to all reviewers’ comments.\nREVIEWER COMMENTS\n----------------------------------------------------------------------\nReviewer #1 (Remarks to the Author):\n----------------------------------------------------------------------\nThe work reports an observation of carrier-doped induced interlayer Antiferromagnetic\nto Ferromagnetic phase transition in CrSBr semiconductor. Although electrical control\nof magnetic phase transition is already studied in the CrSBr system, the present work\ndemonstrates the CrSBr/Graphene heterostructure-based lateral spin-valve without\nFM metal contact by exploiting the interlayer charge transfer caused doping effect\ninduced AFM-FM phase transition. The authors have established the tunability of spin-\nvalve magnetoresistance (MR) by pure electrical means and try to explain how\nelectrical means tune the spin polarization. However, the manuscript has the following\nissues to be addressed. Without addressing these issues, the manuscript is not suitable\nfor publication in Nature Communications in its current form.\nResponse to Reviewer #1: We thank the reviewer for carefully evaluating our\nmanuscript and for the constructive comments that helped us to improve the clarity and\npresentation of our work. We have substantially revised the manuscript accordingly to\naddress all the comments and hereby provide the detailed point-by-point responses.\nReviewer #1 comment #1: “Local maximum near the T ~ 132 K in figure 2c is likely\nN\nreflecting reduced scattering from spin fluctuations after AFM ordering”. Authors\nshould explain the correlation between the shift in the characteristic maximum and\ndoping-induced modulation of magnetic ordering more comprehensively.\nResponse #1: We thank the reviewer for this insightful comment. The temperature of\nthe conductance maximum tracks the magnetic ordering temperature; upon Li\n1\nintercalation that drives an AFM-FM transition, the conductance maximum shifts\nupward because T increases.\nC\nHere is the physical picture. In CrSBr, the conductance G(T) ∝ n(T)μ(T). The\nmaximum value of G(T) appears near the magnetic ordering temperature. Above this\ntemperature, strong spin fluctuations due to the lost magnetic order lower the mobility\nμ; at lower T, semiconductor behavior (decreasing n) dominates, so the conductance\nfalls again, resulting in a peak close to T (AFM) or slightly below T (FM). This is\nN C\nconsistent with classic ferromagnetic-semiconductor theory and experiments, as\ndetailed below.\nIn pristine CrSBr (V = 0 V), G(T) shows a local maximum near 132 K (Fig. R1a,\nLG\nblue curve), coincident with the onset of AFM order. Bilayer data in the literature show\nthe same behavior at T (Fig. R1b; Telford et al., Nat. Mater. (2022)). In monolayer\nN\nCrSBr (FM), the conductance maximum lies slightly below T (Fig. R1c; Telford et al.,\nC\nNat. Mater. (2022)), consistent with theoretical expectations for ferromagnetic\nsemiconductors (Balberg & Helman, Phys. Rev. B (1978); Alexander et al., Phys. Rev.\nB (1976)).\nUpon Li intercalation (V = 6 V), our device undergoes an AFM-FM transition,\nLG\nand the conductance maximum shifts upward to ~207 K (Fig. R1a, red curve). This\ntrend is consistent with recent independent Li-intercalated CrSBr measurements where\nthe peak also appears near 200 K (Fig. R1d inset; Feuer et al., Adv. Mater. (2025)),\nmarking the onset of magnetic order. Additionally, our calculations (Fig. S5) show\nenhanced intralayer exchange interaction with electron doping, supporting a doping-\ninduced increase in T .\nC\nTaken together, these results establish a direct correlation between the position of\nthe conductance maximum and doping-induced modulation of magnetic order. We have\nrevised the main text and figure caption accordingly to explain this correlation more\nclearly.\nRevisions to the manuscript (R1.1):\n- On page 4, 2nd paragraph\n“Pristine CrSBr exhibits semiconducting behavior, with conductance decreasing upon\ncooling and showing a local maximum near 132 K at V = 0 V. This maximum\nLG\ncoincides with the onset of AFM ordering and is attributed to the associated suppression\nof spin-disorder scattering (Telford et al., Nat. Mater. (2022)). Upon intercalation\ndoping (V = 6 V), the conductance maximum shifts to ∼207 K, in consistent with\nLG\n2\nearlier report (Feuer et al., Adv. Mater. (2025)). In ferromagnetic semiconductors, T\nC\ntypically lies slightly above the conductance maximum (Balberg & Helman, Phys. Rev.\nB (1978); Alexander et al., Phys. Rev. B (1976)), as seen for monolayer CrSBr (Telford\net al., Nat. Mater. (2022)). These results indicate that gate-controlled intercalation\ndoping enables effective tuning of the magnetic phase and also increases the magnetic\nordering temperatures.”\nFigure R1 | Temperature-dependent conductance and magnetic order in pristine\nand Li-intercalated CrSBr. a (same as Fig.2c), Conductance of our CrSBr device\nbefore (blue, V = 0 V) and after Li intercalation (red, V = 6 V). The undoped\nLG LG\nconductance maximum occurs near 132 K, consistent with AFM ordering, while after\nLi doping the maximum shifts to ~207 K, indicating a significant increase of T .\nC\nb,\nBilayer CrSBr: G(T) exhibits a local maximum at the Néel temperature T , linking the\nN\nconductance maximum to AFM ordering (reproduced from Telford et al., Nat. Mater.\n(2022)). c, Monolayer CrSBr (FM): the conductance maximum lies slightly below T\nC\n(reproduced from Telford et al., Nat. Mater. (2022)), consistent with theoretical\n3\nexpectations for ferromagnetic semiconductors (Balberg & Helman, Phys. Rev. B\n(1978); Alexander et al., Phys. Rev. B (1976)). d, Li-intercalated CrSBr from an\nindependent study: G(T) curve showing a conductance maximum near 200 K\n(reproduced from Feuer et al., Adv. Mater. (2025)).\nReviewer #1 comment #2: The manuscript reported that the interlayer AFM coupling\nis transformed into interlayer FM coupling after doping. In the undoped system, CrSBr\nhas an easy axis of magnetization. Is there any change in magnetic orientation after\ndoping induced AFM-FM transition? This information should be provided, which is\ncrucial for applications.\nResponse #2: We thank the reviewer for raising this important point regarding the\nmagnetic anisotropy. The easy axis of pristine CrSBr is well-established to be along the\ncrystallographic b-axis (Telford et al., Nat. Mater. (2022)). Based on our experimental\nobservations and theoretical understanding, the magnetic easy axis remains along the\nin-plane b-direction after the doping-induced AFM-FM transition. Here are the supports:\nFirst, our magnetoresistance in Fig. 2d (field // b-axis) shows that the resistance at\nThis directly evidences that the easy axis is preserved upon doping (see Fig. R2a, which\nreproduces Fig. 2d). Of course, angular dependent measurements will provide more\nconclusive evidence. However, our in-situ gate-controlled Li-intercalation experiments\nrequire fast cooling to frozen the doping state and such a fast cooling probe does not\nsupport sample rotation.\nSecond, the strong magnetocrystalline anisotropy in CrSBr theoretically originates\nfrom its intrinsic anisotropic crystal structure. The carrier doping in our study, while\nsufficient to alter the sensitive interlayer exchange coupling, are considered unlikely to\nbe strong enough to fundamentally reorient the robust instrinsic magentic easy axis.\nThis can be supported by the first-principles calculations in literature (Xie et al., ACS\nNano 2023), which shows that electron doping flips the interlayer coupling from AFM\nto FM but the easy axis remains aligned with the in-plane b-axis (Fig. R2b). Recent\nindependent measurements on Li-intercalated CrSBr with fields applied along all three\ncrystallographic axes also confirm that the FM state retains the same easy axis along b-\ndirection (Feuer et al., Adv. Mater. 2025), as shown in Fig. R2c.\nWe have revised the manuscript accordingly to clearly mention the unchange of the\nmagnetic easy axis after doping.\n(same as Fig. 2d in the main text) with field // b-axis. The red arrow indicates that the\nresistance at 1 T coincides with that at 0 T, demonstrating stable FM magnetization\nalong the b direction at zero field. b, Theoretical result reproduced from Xie et al., ACS\nNano (2023), showing the AFM–FM transition as a function of doping. The inset marks\nthe magnetization orientation and crystallographic axes, indicating the easy axis\nremains along the in-plane b direction. c, Magnetic susceptibility along the a, b, and c\naxes in Li-intercalated CrSBr sample, confirming that the FM easy axis remains along\nthe in-plane b-direction after doping (reproduced from Feuer et al., Adv. Mater. (2025)).\nRevisions to the manuscript (R1.2):\n- On page 4, 3rd paragraph\n“In contrast, following intercalation at 6 V, the AFM signature vanishes, and the MR\nexhibits a butterfly-shaped hysteresis with zero-field resistance matching that at 1 T,\nindicating the formation of a stable FM ground state with the magnetic easy axis\npreserved along b-direction (Xie et al., ACS Nano (2023); Feuer et al., Adv. Mater.\n(2025)).”\nReviewer #1 comment #3: Magnetic phase transition discussed in the manuscript is an\ninterlayer AFM to FM transition. The intralayer magnetic coupling is FM in the system.\nRegarding the lateral Spin valve device design, the channel will always have an\nintralayer ferromagnetic coupling. Is it accurate to consider the channel to be\ncompletely antiferromagnetic, while the magnetic moments are intralayer\nferromagnetically coupled?\nResponse #3: We appreciate the reviewer’s insightful comment. In pristine CrSBr, the\nmagnetic structure is indeed A-type antiferromagnetic, with intralayer ferromagnetic\n5\ncoupling and interlayer antiferromagnetic coupling (Telford et al., Nat. Mater. (2022)).\nIn our lateral spin-valve devices, however, the situation is spatially inhomogeneous.\nNear the graphene contacts, strong charge transfer leads to a local AFM→FM transition,\nresulting in both intralayer and interlayer ferromagnetic coupling in the contact regions.\nIn contrast, the central channel region (approximately 1 μm away from the contacts) is\nhardly influenced by charge transfer and preserves the A-type AFM order. Therefore,\nwe consider the channel as antiferromagnetic is a reasonable approximation.\nFor clarity, we have explicitly labeled the pristine CrSBr as “A-type AFM” in Fig.\n1a to highlight that the intralayer coupling remains ferromagnetic.\nReviewer #1 comment #4: Why the spin-valve behavior is reproducible only when the\nfield sweep is confined within ±0.3 T and not reproducible if the field sweep is beyond\n±0.3 T.\nResponse #4: We apologize for the lack of clarity that may have caused this\nmisunderstanding. The spin-valve behavior is always reproducible when the magnetic\nfield is swept beyond ±0.3 T. The data used for Fig. 3e were acquired under a full sweep\nrange of ±1 T, and Fig. 3e simply shows the central ±0.3 T window extracted from these\ndata to highlight the spin-valve switching features more clearly. To avoid ambiguity, we\nshow the complete ±1 T magnetoresistance data as Fig. R3, confirming that the spin-\nvalve behavior is robust and reproducible across the entire field range. In addition,\nSupplementary Fig. S7b further demonstrates that repeated sweeps confined within\n±0.3 T also reproduce the effect, highlighting reproducibility under both small- and\nlarge-field cycling.\nRevisions to the manuscript (R1.3):\n- On page 6, 1st paragraph\n“We note that the spin-valve behavior is also reproducible when the field sweep is\nconfined within  0.3 T (Supplementary Fig. S7b).”\n- On page 6, 2nd paragraph\n“We performed MR measurements at different gate voltages over a magnetic field\nsweep of ±1 T (Supplementary Fig. S10) and the central ±0.3 T window is shown in\nFig. 3e.”\nin CrSBr device with Gr contacts (Sample D1). a, MR of the CrSBr device measured\nat various V from -90 V to -40 V. b, Transfer curve of the same device at 2 K. c, MR\nG\nof the same device measured at various V from -20 V to 80 V. Fig. 3e in the main text\nG\nis extracted from this dataset to focus on the ±0.3 T window for clarity. The full dataset\nconfirms that the spin-valve behavior is reproducible across the entire ±1 T range.\nReviewer #1 comment #5: Band structure of the system after doping is required to\ncheck whether the materials remain semiconducting after doping or not. If the CrSBr\ndoes not remain semiconducting and become conducting after doping, then it will not\nbe possible to locally dope the system to device a spin valve with spatially localized\ngraphene contact.\nResponse #5: We apologize for the lack of clarity that may have caused this confusion.\nWe would like to clarify that Li-intercalated CrSBr remains semiconducting, and our\nspin-valve devices use pristine CrSBr, where local charge-transfer doping at graphene\ncontacts creates FM regions while the central channel stays AFM.\n7\n(1) Semiconducting character after doping.\nAs shown by the temperature-dependent conductance (Fig. R1a; same as Fig. 2c in the\nmain text), Li-intercalated CrSBr still exhibits semiconducting behavior, with\nconductance decreasing upon cooling at low temperatures. This provides direct\nexperimental evidence that the material retains a semiconducting band structure even\nafter doping.\n(2) Spin-valve configuration and local doping mechanism.\nFor the spin-valve measurements, we fabricated devices from pristine CrSBr (i.e.,\nwithout Li intercalation), so the channel retains its intrinsic semiconducting band\nstructure. The electronic band alignment at the graphene/CrSBr interface is presented\nin Fig. R4 (same as Fig. S14), where the graphene Dirac point lies significantly above\nthe CrSBr conduction band minimum. This alignment induces strong electron transfer,\nfrom graphene into adjacent CrSBr, producing localized electron doping and a local\nAFM-FM transition confined to the contact region. The uncontacted central channel of\nCrSBr retains its original AFM state, yielding a spatially separated FM/AFM/FM\nstructure necessary for the observed spin-valve behavior.\nWe have revised the main text accordingly, to explicitly mention that the pristine CrSBr\nis used for spin-valve devices.\nRevisions to the manuscript (R1.4):\n- On page 5, 2nd paragraph\n“we next employ the local-doping strategy that exploits interfacial charge transfer from\ngraphene to spatially modulate the magnetic order of pristine CrSBr.”\ngraphene/CrSBr interface. Calculated band structures showing the graphene Dirac\npoint above the CrSBr conduction band minimum, independent of whether van der\nWaals interactions are considered or the number of CrSBr layers. This alignment\nindicates strong charge transfer from graphene to CrSBr, leading to localized electron\ndoping at the contact region and enabling the AFM-FM transition required for spin-\nvalve operation.\nReviewer #1 comment #6: In line 73, the mentioned A-type AFM order is not discussed\nin Supplementary Note 1 and there is no information about the magnetic phase in\nFigure S1, as mentioned in the main text.\nResponse #6: We thank the reviewer for pointing out this issue. Supplementary Note 1\nand Fig. S1 describe the crystal growth process and the method used to determine flake\nthickness, not the magnetic phase. We have corrected the erroneous reference to\nSupplementary Note 1 and Fig. S1 by revising the main text accordingly: “A vdW\nsemiconductor CrSBr (Supplementary Note 1 and Fig. S1), showing A-type AFM order\n(Fig. 1a)…”. We also explicitly label “A-type AFM” in Fig. 1a to clearly illustrate the\nmagnetic structure.\n- On page 3, 1st paragraph\n“A vdW semiconductor CrSBr (Supplementary Note 1 and Fig. S1), showing A-type\nAFM order (Fig. 1a)…”\nFigure R5 | (same as updated Fig. 1a and 1b) Doping-induced magnetic phase\ntransition and spin polarization asymmetry in CrSBr revealed by theoretical\ncalculations. a, Schematic illustration of the layered A-type antiferromagnetic (AFM)\nstate of CrSBr and corresponding spin-resolved density of states (DOS), exhibiting spin\ndegeneracy (P = 0). b, Schematic illustration of the layered ferromagnetic (FM) state\nof CrSBr and corresponding spin-resolved DOS, showing spin asymmetry (P ≠ 0),\nwhich enables spin-polarized transport and tunable spin polarization.\nReviewer #1 comment #7: In line 97, the b direction should be more clearly stated in\nconnection with the unit cell of CrSBr.\nResponse #7: We have revised Fig. 1a to include crystallographic axes and explicitly\nlabel the in‑plane b direction; the text now states that the easy axis is along b-direction\n(R1.7).\nRevisions to the manuscript (R1.6):\n- On page 3, 3rd paragraph\n“with the easy axis oriented along the b-direction (Fig. 1a)”\nReviewer #1 comment #8: In Figure 1a and 1b, y axis for DOS structure should be\n(Energy)-(Fermi Energy)\nResponse #8: We have corrected the y‑axis labels in Figs. 1a and 1b from “Energy (eV)”\n10\nto “E – E (eV)” (Fig. R5; same as updated Fig. 1).\nF\nReviewer #1 comment #9: In line 128, increase in T¬C is concluded to arise from\nelectron-doping-enhanced intralayer effective exchange interactions in CrSBr.\nHowever, doping induced an interlayer AFM to FM phase change in the CrSBr, which\nindicates that doping has a prominent effect on the interlayer exchange coupling. The\nrole of interlayer exchange coupling on the critical temperature should also be\ninvestigated and discussed.\nResponse #9: We thank the referee very much for raising this insightful point. Yes,\ndoping induced interlayer AFM-FM phase change in the CrSBr indicates that doping\nhas a prominent effect on the interlayer exchange coupling. According to our\ncalculations (see Supplementary Table S2 and Figure S5 in the revised SI), the\ninterlayer exchange coupling is antiferromagnetic and only 0.02292 meV for crystalline\nCrSBr. Although electronic doping causes AFM to FM transition, however, the\nmagnitude of interlayer exchange coupling is smaller than intralayer ones by about two\norders of magnitude. Thus, the influence of interlayer coupling on T can be safely\nC\nneglected.\nIn the following, we list the detail for the calculation of the intralayer exchange coupling\nJ ┴ (Details for J can be found in Response#14):\nn\nFor the estimation of exchange parameters, we adopt a 2×2×1 supercell for the bulk\nCrSBr, which contains two layers along the c axis. The total energy of the supercell\nstructure can be written as\nE E   JS S , (1)\nintralayer il jl'\ni,j，ll'\nwhere E is the energy of two layers considering only intralayer interactions, J\nintralayer\nis the nearest-neighbor interaction of Cr atoms in adjacent layers, S (S ) represents the\nil jl’\nspin operator in site i(j) of layer l(l’).\nFor FM CrSBr, the total energy can be written as\nE 2E 16JS2 (2)\nFM FMlayer\nwhere S=3/2 is the total spin of the Cr3+ ion (Wang et al., Phys. Rev. B 108, 054401\n(2023)), and E is the energy of one FM CrSBr layer.\nFMlayer\nE 2E 16JS2 (3)\nAFM FMlayer\nCombining Eqs. (2-3), we can derive the expression for the interlayer exchange\ncoupling parameter as:\nE E E E\nJ  FM AFM  FM AFM (4)\n32S2 72\nFor the pristine CrSBr, we calculated the total energies of both the FM and AFM states,\nand obtained J 0.02292meV, which is consistent with previous studies (Wang et\nal., Phys. Rev. B 108, 054401 (2023)).\nFor different electronic doping levels, we tune the charge carriers by changing the total\nnumber of electrons in the unit cell with a compensating jellium background of opposite\ncharge based on the relaxed pristine structure. Calculated results are listed in\nsupplementary Table S2. As shown in the table, electronic doping causes AFM to FM\ntransition and also significant magnification in the magnitude of the interlayer exchange\ncoupling. However, compared to intralayer ones, the interlayer exchange coupling has\nnegligible effect on the critical temperature.\nRevisions to the manuscript (R1.7):\nWe have added Supplementary Table S2 and updated Supplementary Fig. S5 and S6 in\nthe revised SI.\n- On page 5, 1st paragraph\n“As the magnitude of interlayer exchange coupling is smaller than intralayer ones by\nabout two orders of magnitude (see Supplementary Note 3 and Supplementary Table\nS2), this increase in T primarily arises from electron-doping-enhanced intralayer\nC\neffective exchange interactions in CrSBr as supported by our calculations\n(Supplementary Fig. S5), underscoring the effective thermal stabilization of FM order\nthrough carrier doping33.”\nTable R1 (same as Supplementary Table S2) | Exchange parameters of bulk CrSBr.\nJ , J , and J are intralayer ones (see Figure S5) and J ┴ is the interlayer exchange\n1 2 3\n12\ncoupling parameters between nearest-neighbor Cr atoms in adjacent layers.\nDoping\nJ J J J┴\n1 2 3\nconcentration\n(meV) (meV) (meV) (meV)\n（1027/m3）\n-1.50102 -5.445 -7.405 -7.515 -1.34083\n-1.00068 -4.597 -7.333 -7.732 -1.05542\n-0.50034 -3.653 -7.161 -7.718 -0.70472\n0 -2.942 -7.389 -7.515 0.02292\n0.25017 -2.124 -6.887 -8.365 -0.02278\n0.50034 -1.619 -6.879 -9.389 -0.03694\n0.75051 -1.14 -6.891 -10.288 -0.07486\n1.00068 -0.703 -6.913 -11.096 -0.12417\n1.25085 -0.314 -6.946 -11.883 -0.18167\n1.50102 0.025 -7.020 -12.680 -0.15611\n1.75119 0.302 -7.077 -13.430 -0.12403\nFigure R6 (same as updated Supplementary Figure S5) | Calculated intralayer\nexchange interaction as a function of carrier density for bulk CrSBr. a, Crystal\nstructure of CrSBr in the a-b plane, with definitions of the intralayer exchange\ninteractions Jn corresponding to the nearest-neighbor (J1), next-nearest-neighbor (J2),\nand third-nearest-neighbor (J3) couplings. b, First-principles calculated values of the\nintralayer exchange interactions Jn and interlayer nearest-neighbor exchange\ninteraction J ┴ as a function of electron doping concentration for bulk CrSBr. Within\nthe calculated carrier density range, the overall effective exchange interaction is\nenhanced, contributing to the experimentally observed increase in magnetic critical\ntemperature (Fig. 2f).\nis no Figure 1e in the manuscript.\nResponse #10: We thank the reviewer for carefully pointing out this mistake. We\ncorrected the erroneous citation “Fig. 1e” to “Fig. 1c” and revised the main text\naccordingly.\nRevisions to the manuscript (R1.8):\n- On page 5, 2nd paragraph\n“Theoretical studies predict strong charge transfer at the CrSBr/Gr interface and\neffective electron doping that can induce an AFM-to-FM transition in thin-layer CrSBr\n(Xie et al., ACS Nano (2023); (also see Fig. 1c)”\nReviewer #1 comment #11: In line 182, it is mentioned that both electrodes exhibit\npositive spin polarization and after the critical bias, the two electrodes acquire opposite\nspin polarization. How the author evaluated and confirmed the similar or opposite spin\npolarization of the two electrodes need to be discussed. Further, the calculation of spin\npolarization of different heterostructures is not sufficient to interpret how the spin\npolarization of the two Graphene contacted electrodes are controlled by electrical\nmeans. Their claim of gate tunable spin polarization reversibility is not established\nclearly.\nResponse #11: We thank the reviewer for raising this critical point. We determine the\nsign and reversal of the spin polarizations at the two graphene contacted electrodes from\nour spin-valve measurement combined with theoretical modeling. Under a finite bias,\nthe two graphene/CrSBr electrodes probe different energy regions of the spin-split\ninterfacial band structure; a global gate shifts both Fermi levels relative to those bands.\nThis produces parallel to antiparallel (and vice versa) polarization configurations at the\ncontacts, which we confirm experimentally via gate-tunable reversals of the spin-valve\nMR.\nTheoretically, we evaluate the spin polarization defined as the difference between\nspin-up and spin-down density of states, which are well applied in literature [Julliere,\nPhys. Lett. A 54, 225 (1975); Mazin, Phys. Rev. Lett. 83, 1427 (1999); Min et al., Nat.\nMater. 21, 1144 (2022)]).\nFor each graphene/CrSBr contact, we compute the spin-resolved density of states.\nresolved electronic states within the transport energy window defined by its local\nelectrochemical potential. Under a finite bias V , these transport windows are offset\nDS\nbetween the two contacts and can be rigidly shifted together by the global gate V ,\nas\nG\nillustrated in Fig. R6. When the dominant spin species within the respective energy\nwindows differ, the two electrodes acquire opposite spin polarization. Using the first-\nprinciples calculated density of states of the graphene/CrSBr contact, we quantitatively\ncalculated P P at V =0.48V as a function of gate (Fig. 4d), clearly showing the gate-\n1 2 DS\ndependent sign change of P P .\n1 2\nIn experiments, we confirm this gate tunable spin polarization reversibility from\nspin-valve MR measurements. In our device, the two-contact configuration yields\ndistinct resistance states (“1 or 3” and “2”). As shown in Fig. 4a–b, at a large fixed V\nDS\nvarying V reversibly flips the spin-valve MR sign/state, which directly implies a\nG\nreversal of P P (parallel ↔ antiparallel).\n1 2\nThe excellent quantitative agreement of our theoretical estimated carrier density at\nsign reversal condition with the experimental data (Fig. 4d and Supplementary Note 7)\nprovides a strong support of our claim of gate tunable spin polarization reversal.\nWe have added new schematic figure in the SI (new Supplementary Fig. S13) to\nexplain our model more clearly and revised the manuscript accordingly.\nRevisions to the manuscript (R1.9):\n- On page 6, 3rd paragraph\n“The spin polarization of each electrode is determined by the distribution of spin-\nresolved electronic states within the transport energy window defined by its local\nelectrochemical potential. Under a finite bias V , these transport windows are offset\nDS\nbetween the two contacts and can be rigidly shifted together by the global gate V ,\nas\nG\nillustrated in Supplementary Fig. S13. When the dominant spin species within the\nrespective energy windows differ, the two electrodes acquire opposite spin polarization.”\nshowing how bias and gate voltages modulate the spin polarization of the two\ngraphene (Gr)/CrSBr electrodes. The gray region denotes the transport energy\nwindow of the Gr/CrSBr electrode near the conduction band bottom. Spin polarization\non each side is evaluated by integrating the spin-resolved density of states: in the left\npanel the minority band dominates, yielding P < 0, while in the right panel the majority\n1\nband dominates, giving P > 0. Under a finite bias V , the relative spin polarizations\nof the two electrodes depend sensitively on the band structure, while the global gate\nvoltage simultaneously shifts both Fermi levels (E and E ), providing additional\nF1 F2\ntunability. The configuration illustrated here corresponds to the right case in Fig.4b,\nwhere state “2” represents a high-resistance state arising from opposite spin polarization\nof the two electrodes.\nReviewer #1 comment #12: Some syntax error in Supplementary note 2.\nResponse #12: We thank the reviewer for noticing this. We have carefully checked\nSupplementary Note 2 and corrected the syntax errors in the revised version.\nReviewer #1 comment #13: A more comprehensive discussion on confirmation of the\nSTT effect driven magnetic phase transition in the device configuration with graphene\ncontacts is required.\nspin-transfer torque (STT) mechanism, we provided the following evidence:\nFirst, with graphene contacts, the AFM MR feature near ~0.4 T decreases\nmonotonically with increasing bias (or current density) and eventually vanishes (Fig.\n5a and 5b). This behavior is consistent with a current-induced torque effect that higher\nspin-current increases the torque aligning the AFM-couped spins into an FM\nconfiguration.\nSecond, as a control experiment, in Au-contacted devices, the MR is essentially\nindependent of bias voltage (Supplementary Fig. S18b). This strong bias dependence\nappears only with graphene contacts, exactly what is expected if spin-polarized carriers\nare injected only at graphene/CrSBr junctions and transfer angular momentum to the\nchannel’s AFM spins.\nThird, we ruled out the possibility of pure heating effect. If Joule heating dominated,\nsimilar bias dependence would appear in Au-contacted device but actually it does not.\nAlso, with increasing bias, the AFM MR decreases whereas the coercive field remains\nunchanged (Fig. 5e). If heating effects caused temperature variations, the coercive field\nshould change as shown in Fig. 5d. Moreover, the threshold current density is extremely\nlow in our case, making a thermal scenario unlikely.\nTaken together, these observations provide a consistent and comprehensive\nconfirmation of an STT-mediated AFM-FM transition in graphene-contacted CrSBr\ndevices. We have reorganized the discussion on Page 8 and 9 accordingly in the revised\nmanuscript.\nReviewer #1 comment #14: Details of the theoretical calculation of intralayer\nexchange coupling is required.\nResponse #14: The Hamiltonian of the system can be written as Eq. (1) (Response\n#9), where the interlayer spin Hamiltonian is\nH E   J S S   J S S   J S S (5)\ninterlayer 0 1 il jl 2 il jl 3 il jl\nl i,j i,j i,j\nHere <i,j>, << i,j >>, and <<< i,j >>> represent nearest-, next-nearest, 3rd-nearest\nneighbors, and J is nth-nearest-neighbor exchange parameters. S (S ) represents the\nn il jl\nspin operator in site i(j) of layer l.\nFor the estimation of intralayer exchange parameters, we also adopt the 2×2×1 supercell\n17\nfor the bulk CrSBr, which contains two layers along the c axis. There are four\nparameters in Eq. (5), therefore, we need 4 equations to solve them. For the calculation\nof intralayer coupling, we neglect the influence of interlayer coupling. Note that there\nare 16 Cr atoms in one supercell and the easy axis for CrSBr is b axis. For simplicity,\nwe adopt inversion symmetric settings for the magnetic configurations, which means\nthe inversion symmetric atoms in the lower layer have the same magnetic configuration\nas those in the upper layer. In the following, we list the 4 configurations (Fig. R7)\nadopted and the corresponding total energies.\nFigure R7. Four magnetic configurations used for the calculation of intralayer\nexchange parameters of the upper layer in a 2×2×1 supercell structure of CrSBr.\n(1) FM:\nBoth layers are FM. For each Cr atom, it has 2 nearest neighbors (NNs), 4 next-\nnearest neighbors (NNNs), and 2 next-next-nearest neighbors (NNNNs). Therefore,\nthe energy for one Cr atom can be written as:\n1\n  2J 4J 2J S2 c, (6)\n1 2 1 2 3\nwhere S=3/2 is the total spin for a Cr3+ ion, and c is a constant. Because there are 16\nCr atoms in one supercell, therefore, the total energy for this FM configuration can be\nwritten as:\nE =16=16S2J +2J +J E , (7)\n1 1 1 2 3 0\nwhere E is a constant.\n0\n(2) Zigzag-AFM:\nFor one Cr atom, it has two NNs aligning parallel with it, two NNNs aligning parallel\nwith it, two NNNs aligning anti-parallel with it, and 2 NNNs aligning anti-parallel with\n18\nit. As a result, the NNNs interactions cancel with each other, and the total energy for\none Cr atom can be written as:\n1\n  2J 2J S2 cJ J S2 c， (8)\n1 2 1 3 1 3\nIt turns out that all atoms have the same exchange interaction. And thus\nE =16=16S2J J E . (9)\n2 1 1 3 0\n(3) AlterAFM:\nThe total energy for this configuration can be written as:\nE =16S2J 2J J E . (10)\n3 1 2 3 0\n(4) Line-AFM:\nThe total energy for this configuration can be written as:\nE =16S2J J E . (11)\n4 1 3 0\nCombining the above Eqs. (7)(9-11), we arrive at:\nJ (E E )/32S2\n1 2 4\n\nJ (E E )/64S2\n\n2 1 3\nJ (E 2E E )/64S2\n3 1 2 3\n\nE (E E 2E )/4\n\n0 1 3 4\nTherefore, after obtaining the total energies of the above four configurations, we can\ncalculate the corresponding interlayer exchange couplings. First-principles calculations\nfor bulk CrSBr were preformed using the VASP software and a k-point mesh of 9×7×4.\nThe other parameters were the same with those listed in Supplementary Note 6. The\nintralayer exchange parameters were calculated to be J =-2.942, J =-7.389, and J =-\n1 2 3\n7.515 meV (Table S2), which are also consistent with previous studies (Wang et al.,\nPhys. Rev. B 108, 054401 (2023)). The calculated J is two-orders-of-magnitude larger\nn\nthan the interlayer exchange coupling parameter, justifying our omission of interlayer\nexchange coupling in the calculation of intralayer exchange parameters.\nFor different electronic doping levels, we tune the charge carriers by changing the total\nnumber of electrons in the unit cell with a compensating jellium background of opposite\ncharge based on the relaxed pristine structure. The obtained AFM-FM transition\nqualitatively agrees well with previous studies (Xie et al., ACS Nano 17, 22684–22690\n19\n(2023)). The variation of interlayer exchange parameters is listed in Table S2 and\nplotted in the revised Figure S5.\nRevisions to the manuscript (R1.14):\nWe have included the above details in Supplementary Note 3 in the revised SI.\n20\n----------------------------------------------------------------------\nReviewer #2 (Remarks to the Author):\n----------------------------------------------------------------------\nIn their manuscript Zhao et al. investigated doping by lithium intercalation and\nelectrostatic gating (?) in few-layer CrSBr devices with graphene (or Au) contacts by\nmeasuring MR and performing theoretical modelling (DFT, Monte Carlo, toy model for\nmagnetization). They observe an AFM-to-FM phase transition by intercalation doping.\nThey claim that the devices with graphene contacts form lateral spin valves exhibiting\nspin transfer torque.\nI think that the manuscript is in principle interesting, however, lacks clarity and is\ndifficult to follow for a slightly more general audience due to use of many buzz words\nand technical jargon that is not explained. I recommend reconsideration after major\nrevision and have the following comments:\nResponse to Reviewer #2: We thank the reviewer for carefully reading our manuscript\nand for recognizing the interest of our study. In this revised manuscript, we have\nsubstantially rewritten the text to improve readability, removed unnecessary jargon, and\nprovide additional details/data to better support our claims. We have also clarified the\nexperimental design with new descriptions and schematics by explicitly distinguishing\nthe two complementary approaches in our study: (i) global Li intercalation doping,\nwhich demonstrates that carrier doping can drive an AFM–FM phase transition in\nCrSBr and confirms theoretical predictions, and (ii) local graphene charge-transfer\ndoping, which enables gate-tunable lateral spin-valves with spin transfer torques for\nspintronic device applications. We hope these revisions have substantially improved the\nclarity and accessibility of the manuscript. Below we provide a point-by-point response\nto each of the reviewer’s comments.\nReviewer #2 comment #1: In the abstract, the authors write “in which carrier doping alone drives a reversible, zero-field AFM to ferromagnetic (FM) phase transition”. The\nauthors should add that this is by intercalation doping, which is rather different from\nregular field effect doping. Intercalation with lithium also changes interlayer spacing,\nwhich itself has a strong effect on magnetic order. There have been prior studies on\nintercalation doping in CrSBr (i.e. ref. 33), where AFM-to-FM transitions have also\nbeen demonstrated. What makes the results presented here novel?\nResponse #1: We thank the reviewer for this important comment. In the revised abstract,\nwe have modified the above-mentioned wording to “in which carrier doping induced\nby gate-controlled intercalation drives a reversible, zero-field AFM to ferromagnetic\n21\n(FM) phase transition”. This clarifies that the observed phase transition is achieved via\nintercalation doping rather than conventional field-effect doping.\nWe acknowledge that AFM-to-FM transitions in Li-intercalated CrSBr have been\nrecently demonstrated (ref. 33, Feuer et al. Adv. Mater. (2025)). However, our approach\nis methodologically distinct and provides new insights.\nFirst, we use electrically controlled Li intercalation by ionic gating to tune the\nphase continuously and reversibly within a single flake device, while they employed\npost-synthetic chemical intercalation that irreversibly modifies the bulk crystals (ref.\n33). Our method enables to track the stepwise evolution from AFM → mixed phases\n→ uniform FM with zero-field remanence as a function of gate bias and temperature\n(Fig. R8 / new Fig. S3 for Sample D1), allowing device-level programmability.\nSecond, although Li intercalation can also modify the interlayer spacing, our results\nshow carrier doping itself plays a decisive role in tuning the magnetic order in CrSBr.\n(i) Our theoretical calculations predict that electron doping strengthens intralayer\nexchange and flips interlayer coupling from AFM to FM within experimental carrier\ndensities (Fig. S5 and Fig. 1c), supported by our gate-controlled phase transition\nexperiment with an enhanced T . These calculations were performed with unmodified\nC\nlattice constant, indicating that the carrier density itself is essential in controlling the\nexchange interaction.\n(ii) We additionally performed experiments using a conventional ionic liquid\n(DEME-TFSI) for pure electrostatic gating in CrSBr. The preliminary results are shown\nin Fig. R9. We observe bipolar enhancement of MR hysteresis under both electron and\nhole doping—consistent with a doping-driven AFM-to-FM tendency, but the device\ndoes not reach a fully FM state (Fig. R9). This likely reflects electrostatic doping\nconfined within top layers, whereas Li intercalation provides volumetric doping and\nachieves the uniform FM state (Fig. 2d). Nevertheless, these results reinforce the key\nrole of carrier doping in driving magnetic phase transitions and we are continuing to\nconduct more systematic investigation using electrostatic gating.\nWe have also revised our introduction accordingly to clearly situate our work\nrelative to ref.33. We want to emphasize that the novelty of our study lies not only in\ndemonstrating a global gate-tunable AFM-FM transition within a single device, but also\nin how we uniquely exploit this transition to enable all-electrical spintronic device\nplatform.\nRevisions to the manuscript (R2.1):\n22\n- On page 2, abstract\n“in which carrier doping induced by gate-controlled intercalation drives a reversible,\nzero-field AFM to ferromagnetic (FM) phase transition.”\n- On page 3, 3rd paragraph\n“Previous attempts to modulate magnetism in CrSBr using conventional solid\ndielectrics have induced only modest changes in the coercive field of thin flakes\n(Tabataba-Vakili et al., Nat. Commun. (2024)), while effective gate control in thicker\nflakes remains even more challenging. More recently, chemical lithium intercalation\nhas been shown to induce an AFM-to-FM phase transition in bulk CrSBr (Feuer et al.,\nAdv. Mater. (2025)), highlighting the critical role of carrier doping in tuning its\nmagnetic ground state. Here, we employ an electrically controlled ionic-liquid gating\napproach that enables reversible, high-density carrier accumulation and continuous\ncontrol of the magnetic phase transition in CrSBr flakes, allowing systematic mapping\nof the phase diagram under electrostatic modulation.”\n- On page 4, 3rd paragraph\n“To further verify this magnetic transition, we performed the magnetoresistance (MR)\nmeasurements with the external magnetic field (B) sweeping along the easy axis (b-\ndirection) at different liquid-gate voltages and temperatures. The systematic evolution\nof MR is provided in Supplementary Fig. S3.”\nFigure R8 (same as new Supplementary Fig. S3) | Evolution of magnetoresistance\n(MR) in CrSBr devices under gate-controlled Li intercalation. a–d, Temperature-\ndependent MR curves measured at different gate voltages: a, 0 V, b, 1 V, c, 3 V, and d,\nnon-uniform Li intercalation induces inhomogeneous magnetic domains, leading to\nstrong spin scattering and an anomalously large MR amplitude exceeding 200%. As the\ngate voltage increases to 3 V and 6 V, the MR amplitude gradually decreases, reflecting\n23\nthe suppression of AFM domains and the progressive evolution toward a uniform FM\nstate. This systematic evolution demonstrates the continuous, gate-tunable AFM–FM\ntransition enabled by ionic-liquid-controlled Li intercalation.\nFigure R9 | Effect of electrostatic doping in CrSBr via conventional ionic-liquid\ngating. Magnetoresistance measurements of a 6L CrSBr device at 2 K under\nelectrostatic doping using a conventional ionic liquid (DEME-TFSI). Both electron\ndoping (V > 0 V) and hole doping (V < 0 V) show enhanced MR hysteresis,\nLG LG\nconsistent with a doping-driven AFM→FM tendency. However, the system does not\nreach a fully ferromagnetic state, unlike in the Li-intercalated case (Fig. 2d), likely\nbecause the electrostatic doping primarily affects only the top layers while the bottom\nlayers remain antiferromagnetic.\nReviewer #2 comment #2: In the abstract, the authors write “tunability exceeding\n100%”. What does that mean? They use this expression several times without\nexplaining it. In line 260 they state “gate-controlled spin polarization exceeding 100%”.\nWhat’s a more than 100% spin polarization? That does not make any sense to me.\nResponse #2: We apologize for the confusing terminology and thank the reviewer for\npointing it out. In the FM state of CrSBr and the CrSBr/Gr contact, the conduction band\nbottom is dominated by a single spin channel (Fig. 1b and Supplementary Fig. S14), so\nthe spin polarization is near unity (i.e, |P| ~ 1). With gate and bias, we observe sign\nreversion of the spin-valve MR. The phrase “tunability exceeding 100%” was meant to\ndescribe the sign reversal of the spin polarization and emphasize the large tunability.\nWe recognize this is non-standard and misleading language. We have removed this\nphrase throughout the manuscript and replaced it with wording that reflects gate-\ncontrolled sign reversal of spin polarization in the revised manuscript accordingly.\n- On page 2, abstract\n“with gate-controlled spin polarization reversal”\n- On page 7, 2nd paragraph\n“This result confirms that the gate modulation can fully reverse the spin polarization in\nour CrSBr spin-valve device, demonstrating large tunability.”\n- On page 9, 2nd paragraph\n“with gate-controlled spin polarization reversal and large tunability.”\nReviewer #2 comment #3: The authors refer to samples D15, D41, D66 and so on.\nRenaming their samples as 1, 2, 3, etc or some other more obvious nomenclature would\nhelp with readability.\nResponse #3: We thank the reviewer for this helpful suggestion. The original labels are\ndirectly from our experimental records. Following your advice, we have simplified the\nnomenclature of the devices in the revised manuscript and now replaced with sequential\ndevice IDs (Sample D1, D2, D3, …) to improve readability.\nHere is the mapping table linking the former labels to the new device numbers to\nprevent any ambiguity when comparing with earlier drafts.\nOriginal device label D66 D15 D41 D18\nNew device IDs D1 D2 D3 D4\nReviewer #2 comment #4: In line 97 onward, the authors write “Previous attempts at\ngate control using conventional solid dielectrics have induced only modest changes in\nthe coercive field in thin CrSBr flakes… we employ ionic gating to accumulate higher\ncarrier density in inducing magnetic phase transition in CrSBr”, which sounds like they\nare doing something particularly novel here. However, as mentioned above lithium\nintercalation doping has already been achieved (i.e. ref. 33), even going to significantly\nhigher doping densities. This text should be rephrased to better place the manuscript\nwithin the state of the art.\nResponse #4: We thank the reviewer for this valuable suggestion. We acknowledge that\nRef. 33 (Feuer et al., Adv. Mater. (2025)) has indeed firstly demonstrated lithium\nintercalation–induced AFM-to-FM phase transitions in CrSBr. However, our approach\nis methodologically distinct and provides new insights, as detailed in Response #1.\nIn the revised manuscript, we have rephrased the text accordingly to clearly situate\n25\nour work relative to ref.33 and further emphasized the novelty of our study.\nRevisions to the manuscript:\n- On page 3, 3rd paragraph\n“Previous attempts to modulate magnetism in CrSBr using conventional solid\ndielectrics have induced only modest changes in the coercive field of thin flakes\n(Tabataba-Vakili et al., Nat. Commun. (2024)), while effective gate control in thicker\nflakes remains even more challenging. More recently, chemical lithium intercalation\nhas been shown to induce an AFM-to-FM phase transition in bulk CrSBr (Feuer et al.,\nAdv. Mater. (2025)), highlighting the critical role of carrier doping in tuning its\nmagnetic ground state. Here, we employ an electrically controlled ionic-liquid gating\napproach that enables reversible, high-density carrier accumulation and continuous\ncontrol of the magnetic phase transition in CrSBr flakes, allowing systematic mapping\nof the phase diagram under electrostatic modulation.”\nReviewer #2 comment #5: In line 141 onward, the authors write “Theoretical studies\npredict strong charge transfer at CrSBr/Gr interface that can induce an AFM-to-FM\ntransition in thin-layer CrSBr” referencing two articles. I noticed that this statement is\nnot supported by the cited ref. 16, which does not make any theoretical predictions\nabout charge transfer at CrSBr/Gr interfaces.\nResponse #5: We thank the reviewer for carefully noting this mistake. Indeed, ref. 16\ndoes not contain a theoretical prediction of charge transfer at CrSBr/graphene interfaces,\nso its citation here was incorrect. We have removed ref. 16 and retained only the\nappropriate theoretical article in the revised manuscript.\nReviewer #2 comment #6: In line 142 the authors write “(also see Fig. 1e)”, however,\nthere is no Fig. 1e in their manuscript.\nResponse #6: We thank the reviewer for carefully pointing out this mistake. We\ncorrected the erroneous citation “Fig. 1e” to “Fig. 1c” and revised the main text\naccordingly.\nRevisions to the manuscript (R2.6; same as R1.8)\n- On page 5, 2nd paragraph\n26\n“Theoretical studies predict strong charge transfer at the CrSBr/Gr interface and\neffective electron doping that can induce an AFM-to-FM transition in thin-layer CrSBr\n(Xie et al., ACS Nano (2023); (also see Fig. 1c)”\nReviewer #2 comment #7: From line 152 onwards, the authors refer to a gate voltage\nVG, which is not previously defined and not indicated in any sample illustrations. Are\nthe authors referring to some undefined global back gate? The authors should clarify\ntheir structure and explicitly state what they are doing. VG should appear in a sample\nillustration. Do I understand correctly that from line 133 onward the authors are no\nlonger using ionic gating but regular electrostatic gating?\nResponse #7: We thank the reviewer for catching this omission and apologize for the\nlack of clarity. The reviewer’s understanding is correct. V refers to a global back gate\nG\napplied to the doped Si substrate beneath 285nm SiO . In the spin-valve experiments\n2\n(from line 133 onward), we no longer use ionic gating but instead rely on regular\nelectrostatic back-gating.\nTo clarify, we have revised the text accordingly to define V , distinguished it from\nG\nthe ionic-liquid gate V , and updated Fig. 3 (reproduced as Fig. R10) with a schematic\nLG\nlabeling V , V , and the device structure.\nG DS\nRevisions to the manuscript (R2.7):\n- On page 18, updated Fig.3\nWe have updated Fig. 3 (reproduced as Fig. R10) to include a schematic of the device\nstructure (Fig.3a). The illustration now labels the CrSBr channel, graphene electrodes,\nsource/drain, the SiO /Si substrate, and the applied voltages V (back-gate) and V .\n- On page 5, 2nd paragraph\n“we next employ the local-doping strategy that exploits interfacial charge transfer from\ngraphene to spatially modulate the magnetic order of pristine CrSBr.”\n“Figure 3a and 3b show the schematic and optical image of our CrSBr/Gr\nheterostructure device (Sample D2), where two graphene stripes serve as electrodes and\nthe global back-gate voltage V is applied to the doped Si substrate.”\nG\nGr contacts on a 285 nm SiO /Si substrate. The global back-gate voltage V is applied\nto the doped Si substrate; V is applied between the Gr source and drain electrodes.\nDS\nReviewer #2 comment #8: Do I understand the authors correctly that they are claiming\nthat CrSBr in contact with graphene is always in a FM state? If yes, I must disagree.\nSee for example ref. 16 (supplementary Fig. 7). Contact to graphene does not just\nchange the magnetic order in CrSBr. Under certain conditions, probably.\nResponse #8: We thank the reviewer for this valuable clarification and fully agree that\nCrSBr in contact with graphene is not always ferromagnetic. In our experiments, we\nalso observed that the emergence of ferromagnetism depends critically on the quality\nof the graphene/CrSBr interface. Devices with imperfect or weak interfacial contact\nshow no FM response, indicating that the effect is governed by interfacial charge\ntransfer, which is highly sensitive to cleanliness and coupling.\nTo address this, we placed particular emphasis on fabricating high-quality, bubble-\nfree heterostructures. As shown in Figs. S8 and S12a, our best-performing devices\nexhibit clean interfaces without visible bubbles or residues. This improvement arises\nfrom our optimized fabrication procedure: multiple adjacent graphene strips were\nexfoliated in a single step and used directly as electrodes, avoiding contamination from\nsequential transfers. During CrSBr pickup and placement, we adopted a PC-based dry\ntransfer method (Lin et al., ACS Nano, 2011) with an additional thermal expansion–\ncontraction control step. The PC film was heated to 150 °C for adhesion and slowly\ncooled to 60 °C for controlled release, while repeated mild thermal cycles during the\ndrop-down process eliminated trapped bubbles. Finally, the PC layer was dissolved in\ntrichloromethane to obtain a clean, residue-free interface.\nThese results confirm that graphene-induced ferromagnetism in CrSBr is\nconditional, requiring a sufficiently clean and well-coupled interface. We have revised\n28\nthe main text to explicitly clarify this point and included the detailed fabrication\nprocedure in the Methods section.\nRevisions to the manuscript (R2.12):\n- On page 5, 2nd paragraph\n“The CrSBr/Gr interface induces a 73 V shift in graphene’s charge neutrality point,\ncorresponding to a large charge transfer of ~5.51012 cm-2 (calculated from the 285 nm\nSiO gate capacitance and typically required high quality interface between Gr and\n- On page 13, Methods section\n“To ensure high-quality, bubble-free graphene/CrSBr interfaces, we adopted an\nadditional thermal expansion-contraction control step during the transfer process. The\nPC film was heated to 150 °C for adhesion and slowly cooled to 60 °C for controlled\nrelease, while repeated mild thermal cycles during the drop-down process eliminated\ntrapped bubbles. Finally, the PC layer was dissolved in trichloromethane to obtain a\nclean, residue-free interface.”\nReviewer #2 comment #9: Could it be that the state “2” the authors observe in Fig. 3c\nis simply a sign of layer-by-layer spin flip transitioning from one AFM order to the\nother via an intermediate state? This is what it reminds me of. The 0.2 T at which it\noccurs matches well with the critical field of the bilayer. See for example Ref. 16 (Fig.\n3, optical study of trilayer) as well as Liu et al., Phys. Rev. B 111, L140417, where they\nshow the MR for different layer numbers with the layer-by-layer spin flips inducing\nchanges in the MR. Have the authors studied a bilayer CrSBr device? This could give\nclear evidence of the mechanism, as it cannot show this layer-by-layer switching but\nwould presumably show the spin valve behavior.\nResponse #9: We thank the reviewer for this very reasonable and critical question. We\nhave carefully considered whether the intermediate state “2” in original Fig. 3c could\noriginate from a layer-by-layer spin-flip process. After detailed analysis, we conclude\nthat this scenario cannot fully explain our observations, for the following reasons:\n(A) Control experiments with Au contacts.\nLayer-by-layer spin flips are intrinsic to CrSBr and can lead to step-like MR\nfeatures. However, in our control devices with Au–Au or Au–graphene contacts (Figs.\nS8 and S18), although step-like MR can appear, no clear spin-valve behavior is\n29\nobserved. The characteristic spin-valve signal is only present in devices with graphene–\ngraphene contacts, indicating an additional mechanism beyond intrinsic interlayer\nflipping. Furthermore, comparison of Gr–Gr (Fig. 5a; Fig. S17a) and Au–Au (Fig. S18b)\ncontacted devices shows that suppression of AFM magnetoresistance under bias—the\nhallmark of spin-transfer torque (STT)—occurs exclusively with graphene contacts.\nThis supports that the spin polarization originates from the graphene/CrSBr interface,\nconsistent with previous reports on graphene’s proximity-induced spin polarization\n(Ghiasi et al., Nat. Nanotechnol., 2021).\n(B) Gate dependence of the MR signal.\nIf state “2” merely reflected an intermediate spin-flip configuration, its resistance\nshould depend primarily on the magnetic configuration according to the giant\nmagnetoresistance (GMR) model and be always lower than that of the fully\nantiferromagnetic state, largely insensitive to gate modulation. In contrast, our\nmeasurements show that the resistance of state “2” varies significantly with gate voltage\nand can even exceed that of the antiferromagnetic state, inconsistent with a simple\nGMR picture. This pronounced gate dependence indicates that the underlying\nmechanism cannot be attributed solely to layer-by-layer spin flipping. Instead, the\nobservations are more consistently explained by a spin-valve configuration arising from\ncharge-transfer–induced local ferromagnetism at the graphene/CrSBr interface. It is\nfurther supported by our spin-valve model that quantitatively reproduces the\nexperimentally observed MR sign reversal and the corresponding carrier density at the\ntransition point (Fig. 4d; Supplementary Note 6).\nTaken together, these results establish that the intermediate state “2” arises from\nspin-valve operation mediated by spin-transfer torque, rather than a conventional\ninterlayer spin-flip transition. Notably, such behavior is reproducibly observed in both\ntrilayer (Fig. 3; Fig. S17) and four-layer (Fig. S21) CrSBr devices, demonstrating that\nthe effect is robust and reproducible. We agree with the reviewer that experiments on\nbilayer CrSBr devices would provide a more stringent test of this mechanism. However,\nthe fabrication of reliable high-quality bilayer devices remains technically challenging,\nand we identify this as an excellent direction for future work.\nPoint-by-Point Response to Reviewers’ Comments\nREVIEWER COMMENTS\n----------------------------------------------------------------------\nReviewer #1 (Remarks to the Author):\n----------------------------------------------------------------------\nThe authors have addressed the concerns raised and the suggestions provided. This\nmodified version can be accepted for publication.\nResponse to Reviewer #1: We sincerely thank the reviewer for the positive final\nassessment and recommendation for publication. The reviewer’s earlier comments were\nhighly valuable in improving the clarity and rigor of our manuscript, particularly\nregarding the interpretation of the magnetic phase transition, the role of exchange\ninteractions, and the description of the spin-valve mechanism. These suggestions\nsubstantially strengthened both the main text and the Supplementary Information. We\ngreatly appreciate the reviewer’s careful and constructive efforts throughout the review\nprocess.\n----------------------------------------------------------------------\nReviewer #2 (Remarks to the Author):\n----------------------------------------------------------------------\nThe authors have addressed my questions and comments satisfactorily. I believe the\nmanuscript can be published in Nature Communications in its present form.\nResponse to Reviewer #2: We are grateful to the reviewer for the supportive evaluation\nand for recommending our manuscript for publication. The reviewer’s earlier feedback\nled to important improvements in the presentation of our results, including clearer\nterminology, better explanation of the gating scheme and device configuration, and a\nmore precise positioning of our work relative to prior studies. We sincerely appreciate\nthe reviewer’s constructive input, which has significantly enhanced the overall quality\nand readability of the manuscript.\n1"}]

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