Interface-controlled antiferromagnetic tunnel junctions based on a metallic van der Waals A-type antiferromagnet

Domain: physics
Published: 2025-12-05
Editorial outcome: minor_revision

Abstract
Magnetic tunnel junctions (MTJs) are crucial components in high-performance spintronic devices. Traditional MTJs rely on ferromagnetic (FM) materials, but significant improvements in speed and packing density could be enabled by exploiting antiferromagnetic (AFM) compounds instead. Here, we report all-collinear AFM tunnel junctions (AFMTJs) fabricated with van der Waals A-type AFM metal (Fe0.6Co0.4)5GeTe2 (FCGT) electrodes and nonmagnetic semiconducting WSe2 tunnel barriers. The AFMTJ heterostructure device achieves a tunneling magnetoresistance (TMR) ratio of up to 75% in response to magnetic field switching. Our results demonstrate that the TMR exclusively emerges in the AFM state of FCGT, rather than during the AFM-to-FM transition. By engineering FCGT electrodes with either even- or odd-layer configurations, volatile or non-volatile TMR could be selected, consistent with an entirely interfacial effect. TMR in the even-layer devices arose from Néel vector switching. In the odd-layer devices, TMR stemmed from interfacial spin-flipping. Experimental and theoretical analyses reveal a new TMR mechanism associated with interface-driven spin-polarized transport, despite the spin-independent nature of bulk FCGT. Our work demonstrates that collinear AFMTJs can provide comparable performance to conventional MTJs and introduces a new paradigm for AFM spintronics, in which the spin-dependent properties of AFM interfaces are harnessed.

Introduction
Magnetoresistive random access memory (MRAM) has emerged as a promising candidate for next-generation information storage devices due to its unique combination of non-volatility, robust endurance, and potential for scalability1–3. The building block for MRAM is a magnetic tunnel junction (MTJ), typically composed of two ferromagnetic (FM) electrodes separated by a nonmagnetic (NM) barrier and utilizing tunneling magnetoresistance (TMR) to distinguish the relative magnetization orientations of the electrodes4–8. However, these MTJs suffer from large stray fields and are further inhibited by the relatively slow dynamic responses inherent to ferromagnets. These factors hinder high-density and high-speed applications. Antiferromagnetic (AFM) materials, with vanishing stray fields and ultrafast dynamics, have the potential to overcome these limitations9–11. However, the absence of a net magnetization implies a spin-independent nature of antiferromagnets, and hence an AFM tunnel junction (AFMTJ) has long been considered elusive12. Until very recently, AFMTJs have been constructed using two approaches, both of which rely on noncollinear AFM configurations. Electrodes that exhibit noncollinear AFM configurations and host the momentum-dependent transport polarization supportive to TMR are experimentally constructed in the first approach13,14 (Fig. 1a). The second one uses a two-dimensional (2D) Van der Waals (vdW) AFM semiconductor as the barrier for a spin-filter AFMTJ15, where a twisted stacking is introduced to generate a non-collinear alignment of the Néel vectors of the adjacent layer, allowing a magnetic field induced nonvolatile phase transition for a spin-filtering TMR (Fig. 1b). While these advances are significant and promising, an important gap remains in the field of AFMTJs: the realization of AFMTJs based on collinear AFM metals.

Collinear antiferromagnets, with two antiparallel-polarized sublattices, were discovered prior to their noncollinear counterparts16. However, a strong magnetoresistive effect in response to the rotation of the Néel vector in collinear AFM devices has yet to be observed (Fig. 1c). This stems from two major challenges: the lack of a collinear AFM system supportive of convenient Néel vector manipulation, and the inability to generate spin-polarized transport in conventional antiferromagnets. A collinear AFMTJ with a large TMR would not only complete the spectrum of available AFMTJs but also assist in a deeper understanding of the fundamental physics underlying antiferromagnets. From a technological point of view, collinear AFMTJs, especially those utilizing a perpendicular magnetic anisotropy, possess significant advantages in scalability compared to noncollinear AFMTJs. This is due to the absence of magnetic canting at the edges of collinear AFMs.

Results
Here, we present a purely collinear AFMTJ constructed as a Vander Waals (vdW) heterostructure (Fig. 1c). The recently discovered high-temperature vdW AFM metal (Fe0.6Co0.4)5GeTe2 (FCGT) was selected for the device electrodes17–21. FCGT has a so-called A-type collinear AFM stacking, where the magnetic moments within each vdW layer exhibit FM alignment with perpendicular magnetic anisotropy, while the interlayer show AFM coupling, as illustrated in Fig. 2a. Since the A-type AFM materials with odd and even numbers of layers exhibit different properties in the 2D limit, we systematically investigated the transport properties of FCGT with varying numbers of layers (see Supplementary Material Fig. S1). As shown in Fig. 2c, a standard Hall device of even-layered FCGT (6L) exhibits near flat Rxy between −1.8T to +1.8T, indicating its AFM magnetic ground state in this range. With an increase in the perpendicular magnetic field, the FCGT undergoes AFM-to-FM transitions around ±1.8T and adopts a fully FM state at ±3.0T, with a behavior generally found in vdW A-type AFM materials under an applied magnetic field. Hence, as shown in Fig. 2c, the FCGT states and the corresponding magnetic fields can be divided into three states; an AFM state (the blue region, up to 1.8T), an AFM-to-FM transition state (the grey region, between 1.8T and ~3.0T), and a FM state (the yellow region, beyond ~3.0T). In contrast to the relatively flat Rxy in the AFM state of even-layered FCGT, a noticeable zero-field anomalous Hall effect is observed from the Hall device fabricated with odd-layered FCGT (see Supplementary Material Fig. S1).

The typical structure of the AFMTJ device is illustrated in Fig. 2b, where two FCGT electrodes are separated by a semiconductor WSe2 tunneling layer. To systematically investigate the AFMTJ, three types of devices were fabricated. These types differed in the number of layers in the incorporated FCGT. Specifically, the investigation was performed with even-even type (with both FCGT electrodes consisting of even-numbered layers), odd-even type (with odd-numbered FCGT layer on one side and even-numbered FCGT layer in the other side), and odd-odd type (with both FCGT electrodes consisting of odd-numbered layers) devices. Firstly, we focus on measurements obtained from the even-even configuration, named device D1, which exhibited the intrinsic characteristics of AFMTJs due to the absence of the net magnetization in even-layered FCGT. Atomic force microscopy (Supplementary Material Fig. S2) revealed that the top FCGT layer, middle WSe2 layer, and bottom FCGT layer in device D1 had thicknesses of 6.0 nm, 2.8 nm, and 5.9 nm, corresponding to 6L, 4L, and 6L structures, respectively. Given the critical role of the interfaces in MTJs, the pick-up method was used to fabricate the devices (see methods). In contrast to the metallic behavior observed from the FCGT standard hall device, the resistance-temperature curve of the AFMTJ devices shows insulating behavior (Supplementary Material Fig. S3), confirming that the WSe2 layer was pinhole-free and functioned effectively as a tunneling barrier. We next focus on the characteristics of the AFMTJs.

Upon sweeping an out-of-plane magnetic field B within the range ±4T at 10K, a prominent TMR signal was observed in the AFMTJ with even-even configuration. As shown in Fig. 2d, two prominent peaks emerged at ±0.9T, which were within the AFM state and much lower than the AFM-to-FM transition field of FCGT. The highest resistance, RH, of 61.2 kΩ was measured at +0.9T and the lowest resistance, RL, of 35.0 kΩ was measured at +1.5T. Hence, the TMR ratio (RH – RL)/RL reached 75% at 10K, comparable to that of FM-based vdW MTJs22–27. Such a large TMR ratio is unexpected in an AFMTJ due to the spin-degeneracy of an AFM. To eliminate the possibility that the observed TMR phenomenon arose from an AFM-to-FM phase transition, the emergence fields of the TMR and the AFM-to-FM transition fields of FCGT were collected from various devices and systematically compared (Supplementary Materials Fig. S5). The results show a significant gap between the two field regions, providing clear evidence that the TMR effect manifests in the AFM state. In addition to the prominent TMR behavior, a much smaller magnetoresistance transition occurred under a higher magnetic field of up to ±3.0T (Supplementary Material Fig. S3b). This behavior is consistent with a change in the longitudinal magnetoresistance, Rxx, associated with the AFM-to-FM phase transition of FCGT. We note that this AFM-FM transition field is the same as that observed in the intrinsic FCGT hall device and consistent with those previously reported in FCGT17. This indicates that the AFM-to-FM transition behavior of FCGT is preserved in the FCGT/WSe2/FCGT structure, supporting the assertion that the observed TMR behavior at +0.9T originates from the AFM state of FCGT. The emergence of the prominent TMR signal within the AFM state and the negligible magnetoresistance change observed at the AFM-FM transition demonstrate that this TMR effect is an interface effect rather than a bulk effect. During the AFM-FM transition, although the net magnetic moment undergoes significant changes, the interfacial magnetic moment remains stable, leading to only minor fluctuations in magnetoresistance.

To systematically evaluate the performance of vdW AFMTJs, we performed temperature-dependent measurements on device D1. As shown in Fig. 3a, both the TMR ratio and the TMR transition field decrease with increasing temperature. To quantitatively display this phenomenon, we define TMR_max as the maximum TMR ratio and TMR_ZF as the TMR ratio at zero field. As shown in Fig. 3b, a typical volatile TMR behavior is observed, which decreases monotonically with increasing temperature and vanishes above 230K. To further evaluate the interlayer interaction, we define BC1 and BC2 as the critical transition fields where the TMR effect respectively emerges and then vanishes under increasing magnetic field. As illustrated in Fig. 3c, at 10K, the transition fields BC1 and BC2 exhibit values of 0.84T and 0.98T, respectively. Both fields show a gradual decrease with increasing temperature and ultimately vanish at high temperatures. Another even-even device, designated as D5 with 14L FCGT/5L WSe2/8L FCGT, demonstrates analogous characteristics (see Supplementary Materials Fig. S4). We speculate that the interfacial moments serve to switch the Néel vector in FCGT. It should be noted that the interfacial magnetic moments only experience an interlayer magnetic coupling of half intensity compared with the magnetic moment of the inside layers. As illustrated in Fig. 3d, when the magnetic field is increased to BC1, the interfacial moments of one FCGT electrode are flipped first due to the relatively weak interlayer magnetic coupling, causing the Néel vector to switch due to interlayer AFM coupling. When the magnetic field is further increased to BC2, this process occurs in the opposite FCGT electrode. Therefore, BC1 and BC2 can be considered as the “coercivities” of the interfacial moments. The Interface-assisted Néel vector switching is governed by the competition between magnetocrystalline anisotropy energy, AFM exchange energy, Zeeman energy, and domain wall dynamics. Although the two FCGT electrodes in device D1 have identical nominal thicknesses, differences in their local environments—arising from proximity coupling to distinct substrate or capping layers—and variations in defect distributions can lead to different effective anisotropies and domain pinning strengths, resulting in distinct critical switching fields. This asymmetry enables the observation of TMR. We note that such interface-assisted Néel vector switching has also been reported in other A-type antiferromagnets such as Cr2O328. In this scenario, the TMR characteristics of the AFMTJs with even- and odd-layered FCGT electrodes should then differ, since their switching behaviors are different.

To explore this assertion, an odd-even type FCGT/WSe2/FCGT device, named D2, was fabricated. Optical and atomic force microscopy (Supplementary Material Fig. S2) showed that the underlying FCGT layer number was 14L and the upper FCGT layer number was 5L. Hence, a zero-net magnetic moment existed in one side and a residual net magnetic moment existed on the other side. As shown in Fig. 4a and b, typical volatile TMR behavior was observed in this odd-even configuration below 80K. Interestingly, as the temperature increased, non-volatile TMR behavior appeared above 80K with TMR_max coincident with TMR_ZF in Fig. 4b, despite the absence of a pinning layer. The critical transition fields BC1 and BC2 were extracted to deduce the mechanism. Figure 4c shows BC2 gradually approaching zero with increasing temperature, as observed in the even-even AFMTJ devices and indicating that BC2 is related to the interfacial coercivity of the even-layered FCGT electrode in this device. On the other hand, BC1 is associated with the interfacial coercivity of the odd-layered FCGT. As the temperature increases, BC1 first decreases and then clearly increases toward the opposite direction, with a sign change at 80K. This behavior, unprecedented in conventional MTJs, is responsible for the non-volatile TMR at high temperatures.

The temperature-dependent non-volatile TMR behavior and BC1 sign change behavior suggest two competing interactions29–33. Previous report suggests that during ascending or descending magnetic fields from FM states, (Fe0.56Co0.44)5GeTe2 exhibits an intermediate state M1. As shown in Fig. 4d and Fig. S7, the magnetic moments of all even device were asymmetric between the ascending and descending sweeps, attributed to the presence of the M1 alignment and an exchange bias33 interaction in the odd-layered FCGT that results in self-pinning at high temperature. These results are in line with the half-loop transition in the schematic diagram in Figs. 3d and 4d, verifying the switching of the Néel vector in the even layer and the switching of the M1/AFM alignment in the odd layer. The inherent properties of 2D vdW materials thus enable the realization of non-volatile TMR signals in this system with no requirement for an extra pinning layer. We also fabricated odd-odd type devices (Fig. S10) and since the M1/AFM transition occurs in both sides, only volatile TMR was observed.

The observation of conventional TMR behavior in even-even FCGT/WSe2/FCGT and non-volatile TMR behavior in odd-even FCGT/WSe2/FCGT is tantalizing, as it hints at a new underlying mechanism for TMR. Previous studies of TMR in AFMTJs have focused on the mechanisms associated with momentum-dependent34,35 or sublattice-dependent36,37 transport spin polarizations12. However, these two mechanisms can be excluded from our investigation of the behavior in the A-type collinear AFM FCGT, firstly because the FCGT slab maintains a preserved PT symmetry—a combination of inversion symmetry (P) and time reversal symmetry (T)—leading to a spin-degenerate electronic structure. Secondly, the A-type stacking within the vdW structure suggests a negligible intra-sublattice coupling along the out-of-plane direction. Our experiments demonstrate that the interface plays a crucial role in supporting TMR and point to a distinct mechanism associated with the uncompensated interfaces38.

To further elucidate this mechanism, first-principles quantum transport calculations were performed on vdW AFMTJs with A-type AFM electrodes. For illustrative purposes and without compromising generality, we adopted an AFMTJ structure comprising a central vacuum layer serving as the tunnel barrier, with artificial A-type AFM Fe5GeTe2 (A-F5GT) electrodes. This device structure, as depicted in Fig. 5a and S11, allowed us to explore the physics underlying the TMR mechanism. The A-F5GT is designed to host fully occupied atomic sites and ordered Fe-vacancies based on Fe5GeTe2 (Figs. 5a and S11), keeping PT symmetry and A-type AFM properties similar to those of FCGT (Fig. 2a). This circumvents the computational challenge of simulating disordered split sites and doping atoms in FCGT. The PT symmetry in A-F5GT enforces a spin-degenerate electronic structure (Fig. 5b). As a result, the number of conduction channels for the out-of-plane direction is identical for up-spin (σ= ↑) and down-spin (σ= ↓) electrons at any transverse wave vector k||=(kx, ky) (Supplementary Material Fig. S11), implying the absence of bulk-driven spin-polarized transport in this A-type antiferromagnet.

We define the P and AP states in such an AFMTJ according to the relative orientations of the uncompensated interfacial moments, and calculate the associated k||-dependent transmissions TσP(k||) and TσAP(k||) (Fig. 5c). We find T↑P(k||) and T↓P(k||) differ significantly, implying a finite transport spin polarization in the P states (Fig. 5c). On the other hand, we find T↑AP(k||) and T↓AP(k||) are significantly suppressed and become similar. This behavior resembles that of conventional MTJs with identical FM electrodes, and cannot be attributed to the bulk properties of the AFM electrodes. Rather, it stems from interface-driven spin-polarized tunneling. As a result, the total transmission for the P state (TP) is much larger than that for the AP state (TAP), leading to a TMR ratio TMR= TP/TAP as high as ~1000%. We find that replacing the vacuum layer with a realistic 2D insulator does not qualitatively influence the tunneling behavior of such an AFMTJ (Supplementary Material Fig. S12). The TMR ratio predicted by our calculation is larger than that obtained from our experiments. This discrepancy may be attributed to the significant disorder arising from the randomly distributed split sites and dopants in the selected FCGT samples. These introduce additional scattering effects not accounted for in our calculations, and hence significantly suppress the TMR ratio, especially at high temperatures. With this in mind, enhanced TMR and higher operational temperatures may be made possible in AFMTJs by utilizing vdW A-type AFM electrodes with more ordered structures.

We note a recent study reporting TMR in MTJs with (Fe0.8Co0.2)5GaTe2 (FCGaT) electrodes and WSe2 barriers39. Crucially, this TMR originated from a field-induced AFM-FM phase transition, where high-resistance states emerge when one electrode remains AFM while the other becomes FM. This is in contrast to our system, in which the FCGT exhibits TMR in the all-AFM state without bulk FM phase involvement and with inherent elimination of stray fields – a critical advantage for high-density integration. The divergent behaviors between FCGT and FCGaT likely stem from differences in exchange coupling strengths, magnetic anisotropy energies, interfacial cleanliness, and transfer methodologies—aspects warranting future investigation.

Our work demonstrates that uncompensated interfaces fulfill dual critical functions. They generate spin-polarized tunneling currents for magnetoresistive read-out and enable direct bulk Néel vector control for efficient write-in operations in all-AFM spintronic devices. A promising avenue for future exploration would be to use ultrafast optical method to directly detect the Néel vectors switching to study AFM dynamics and to manipulate the Néel vectors with the interface-assisted spin-orbit torque for all-electric AFM spintronic devices, as suggested recently28,40,41. Since most antiferromagnets exhibit uncompensated interfaces along selected growth directions, our approach suggests the possibility to exploit antiferromagnets previously viewed as “spin-independent” for spintronics, establishing a new device engineering paradigm.

In summary, we demonstrate that all-collinear AFMTJs can be successfully constructed as vdW heterostructures using standard techniques. These devices have achieved a TMR comparable to that of conventional MTJs. The A-type AFM stacking of the vdW electrodes facilitates convenient switching and supports nonvolatile TMR with no need for an additional pinning layer. The performance of these AFMTJs is largely unaffected by the thicknesses of the electrodes and barriers. These findings directly corroborate the theoretical proposal of interface-controlled collinear AFMTJs38 and distinguish them from existing noncollinear AFMTJs. From a technological point of view, these exceptional characteristics, combined with the inherent advantages of antiferromagnets, herald significant potential for next-generation MRAM applications.

Methods
Crystal
Single-crystal FCGT was grown by the chemical vapor transport method. Full details can be found in our earlier work17. Single-crystal WSe2 was purchased from HQ Graphene.

Device fabrication and transport measurements
The FCGT and WSe2 flakes were exfoliated onto SiO2(300nm)/Si substrates using blue tape. Ti/Au (5nm/25nm) contacts were patterned by photolithography and e-beam lithography and deposited by magnetron sputtering. Finally, devices were fabricated based on the dry transfer method42. The FCGT, WSe2, and FCGT flakes were sequentially picked up by polydimethylsiloxane/polycarbonate (PDMS/PC) and then transferred onto SiO2/Si chips supporting the pre-patterned Ti/Au electrodes. The entire exfoliation and transfer process was carried out under inert conditions in an Ar-filled glovebox with O2 and H2O concentrations below 0.1 ppm.

Transport measurements were made in a Physical Property Measurement System (PPMS) from Quantum Design, using an SRS Model CS580 and SR830 lock-in amplifier with a measurement frequency of 13.333 Hz.

Data processing for Hall measurements
Due to the non-symmetry of the Hall device, the Hall resistance Rxy was mixed with a small part of the longitudinal resistance Rxx. We processed the Rxy data by using the standard symmetrical formula (Rxy1(+B)-Rxy2(-B))/2 to eliminate the contribution from Rxx, where Rxy1 and Rxy2 represent the Hall resistances measured during descending and ascending magnetic field sweeps, respectively, and B denotes the applied magnetic field. The TMR data are raw data and have not undergone symmetry processing.

First-principles calculations
First-principles calculations of the electronic structure were performed within the density functional theory (DFT)43 using the projector augmented-wave (PAW)44 method implemented in the VASP code45,46. The plane-wave cut-off energy was 500 eV. The k-point meshes used in the calculations were 12×12×6 for bulk Fe5GeTe2 and 12×12×1 for the vdW heterostructures. The exchange and correlation effects are treated within the generalized gradient approximation (GGA) developed by Perdew-Burke-Ernzerhof (PBE)47. The semi-empirical DFT-D3 method parameterizing the van der Waals correction was used in the calculations48.

The non-equilibrium Green’s function formalism (DFT+NEGF approach)49,50 was used to calculate quantum transport, which is implemented in Quantum ATK51. The cut-off energy of 75 Ry, the non-relativistic Fritz-Haber Institute (FHI) pseudopotentials, and k-point meshes of 11×11×101 for Fe5GeTe2-based AFMTJs were used for self-consistent calculations. The k-resolved transmission was calculated using 401 × 401 k-points in the two-dimensional (2D) Brillouin zone (BZ).

Data availability
The data supporting the findings of this study are available from the corresponding author upon reasonable request.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "My questions have been addressed, and the manuscript has been improved accordingly. I would recommend the publication.", "reviewer_2": "The revised manuscript shows improvements in data completeness and mechanistic analysis. However, several key issues remain:\n1. The current manuscript still lacks direct evidence supporting the interfacial moment induced Néel vector switching claimed by the authors. Specifically, the authors should provide experimental evidence of this switching in FCGT or FCGT/WSe2 heterostructures, or at least include additional results showing the influence of the interface on the MTJ response.\n2.The authors should clarify which parameters determine the critical field for interfacial moment induced Néel vector switching, and based on that, explain the origin of the different critical fields observed in the top and bottom FCGT layers with same 6 layers in D1. This issue is particularly important for MTJ devices.\n3.The title should emphasize the roles of the interfacial moment and A-type AFM to avoid overstating the generality of these results.\n4.Fig. 1c should include the interfacial moment, and the mechanism illustration from the Supplementary Material should be moved to the main text.\nThe experimental results are interesting, but I cannot recommend publication in Nature Communications until these issues are fully addressed."}, "author_response": "Response to Reviewers\n\nReviewer #1 (Remarks to the Author):\nMy questions have been addressed, and the manuscript has been improved accordingly.\nI would recommend the publication.\nResponse: We appreciate the Reviewer’s recommendation to publish our manuscript.\nReviewer #2 (Remarks to the Author):\nThe revised manuscript shows improvements in data completeness and mechanistic\nanalysis. However, several key issues remain:\nResponse: We sincerely thank the reviewer for the constructive comments. Below\nplease find our point-to-point response and the corresponding revisions.\n1. The current manuscript still lacks direct evidence supporting the interfacial moment\ninduced Néel vector switching claimed by the authors. Specifically, the authors should\nprovide experimental evidence of this switching in FCGT or FCGT/WSe2\nheterostructures, or at least include additional results showing the influence of the\ninterface on the MTJ response.\nResponse: We thank the reviewer for this insightful comment. We agree that direct\ncharacterization of interface-assisted switching would provide valuable support for our\ninterpretation. However, such measurements are extremely challenging for even-layer\nFCGT due to the absence of net magnetization in the perfectly compensated\nantiferromagnetic state. This compensation prevents conventional magnetic probes\nfrom detecting the ultrafast dynamics of spin flipping, particularly at the interface,\nwhere the signal is inherently weak and transient. While advanced time-resolved\ntechniques—such as ultrafast optical measurements—could in principle access these\ndynamics, they require specialized equipment beyond the scope of the present study.\nWe therefore make a note to address this issue in paragraph 3 on page 9, and will pursue\nsuch direct investigations in a dedicated future work.\nInstead, to substantiate the role of interfacial effects in our devices, we have\nperformed complementary experiments on odd-layer FCGT, where a net magnetization\nand a finite anomalous Hall effect are present. Specifically, we investigated the\nexchange bias effect—an established signature of interfacial effect—on an independent\nHall device fabricated from a 13-layer (13L) FCGT flake. As shown in Figures R1(a,b),\nfield-cooling measurements reveal clear exchange bias below 75 K, evidenced by the\nasymmetry in the coercive fields and with respect to zero field. Notably,\nboth coercive fields become positive above 75 K, coinciding precisely with the\n𝐻𝐻𝐶𝐶+ 𝐻𝐻𝐶𝐶−\ntemperature at which non-volatile TMR emerges in our AFMTJ devices.\nTo connect these magnetic properties with our TMR results, we present a series of\nschematic hysteresis loops in Fig. R1(c–e) that model the interfacial magnetization\nswitching. The blue (biased) and red (unbiased) loops represent the interfacial layers of\nodd- and even-layer FCGT, respectively. In the absence of exchange bias, symmetric\nTMR peaks are expected (Figure R1c, lower panel), which aligns with the experimental\nobservations obtained for the even-even AFMTJ (Fig. R1f). When exchange bias is\npresent with and , the TMR response becomes asymmetric with\nlow-resistance states at zero field, leading to a volatile TMR (Fig. R1d), consistent with\n𝐻𝐻𝐶𝐶+ > 0 𝐻𝐻𝐶𝐶− < 0\nour experimental data for the even-odd AFMTJ at low temperature (Fig. R1g). In\ncontrast, when both coercive fields shift to positive values (as observed above 75 K),\none TMR peak appears at zero field, resulting in non-volatile TMR (Figure R1e),\nmatching the behavior of the even-odd AFMTJs at high temperature (Figure R1h).\nThese results directly show the influence of the interface on the MTJ response.\nIn the revised manuscript, we have included these new results in the Supplementary\nMaterials (Figure S9) to further strengthen the evidence for interface-driven phenomena.\nFigure R1. a, Optical image of 13L FCGT hall device. b, The temperature-\ndependent R (B) curves under +1.5T field-cooling condition. H and H\nxy C+ C−\nrepresent the coercive fields at forward sweep and backward sweep of magnetic\nfield, respectively. c-e, Upper panel: schematic diagram of hysteresis loop of\ninterfacial magnetic moments. Lower panel: corresponding TMR behavior. f-g,\nthe experimental results of D1 and D2, which are reproduced from Figure S8.\n2.The authors should clarify which parameters determine the critical field for interfacial\nmoment induced Néel vector switching, and based on that, explain the origin of the\ndifferent critical fields observed in the top and bottom FCGT layers with same 6 layers\nin D1. This issue is particularly important for MTJ devices.\nResponse: We thank the reviewer for this important question. The critical field for Néel\nvector switching is determined by the interplay among several energy contributions,\nincluding magnetocrystalline anisotropy energy, antiferromagnetic exchange energy,\nZeeman energy, and domain wall dynamics. Among these, the magnetocrystalline\nanisotropy and domain wall dynamics are particularly sensitive to extrinsic factors such\nas interfacial proximity and the presence of defects or disorders.\nIn device D1, although the top and bottom FCGT layers have the same nominal\nthickness (6 layers), their local environments differ significantly. The bottom FCGT\nlayer is interfaced with SiO₂ (substrate) on one side and WSe₂ on the other, while the\ntop layer is sandwiched between WSe₂ and a polycarbonate capping layer. These result\nin distinct interfacial proximities, which can modify effective anisotropy and hence the\ncoercivity (the critical switching field).\nFurthermore, unavoidable defects can locally break crystal symmetry and alter the\nmagnetocrystalline anisotropy constant K [J. Appl. Phys., 1981, 52(3), 2544–2548]].\nSuch defects also act as pinning sites for domain walls, effectively influence the\ncoercive field. It is well established that even small variations in microstructure or\ndefect density can lead to significant differences in switching fields, regardless of\nwhether the material is ferromagnetic or antiferromagnetic. For example, even for the\nsame sample, post-growth annealing—which modifies defect concentrations and\ncrystallinity—can significantly change the coercive field [J. Appl. Phys. 2006, 99,\n08M307]. Similarly, in our system, differences in local environments, defect\ndistributions, and microstructural details between the top and bottom FCGT layers\nprovide a natural explanation for the observed disparity in their critical switching fields.\nThis variability is further supported by experimental evidence: as shown in Figure\nS5a of the Supplementary Materials, both the critical field and the spin-flip field exhibit\nnoticeable fluctuations across multiple FCGT samples, even for these with identical\nthickness, underscoring the sensitivity of the switching behavior for sample-specific\nconditions.\nIn the revised manuscript, we added “The Interface-assisted Néel vector switching\nis governed by the competition between magnetocrystalline anisotropy energy, AFM\nexchange energy, Zeeman energy, and domain wall dynamics. Although the two FCGT\nelectrodes in device D1 have identical nominal thicknesses, differences in their local\nenvironments—arising from proximity coupling to distinct substrate or capping\nlayers—and variations in defect distributions can lead to different effective anisotropies\nand domain pinning strengths, resulting in distinct critical switching fields. This\nasymmetry enables the observation of TMR.” in paragraph 1 on page 6.\n3.The title should emphasize the roles of the interfacial moment and A-type AFM to\navoid overstating the generality of these results.\nResponse: Following this suggestion, we have revised the title to “Interface-Controlled\nAntiferromagnetic Tunnel Junctions based on a metallic van der Waals A-type\nAntiferromagnet”.\n4.Fig. 1c should include the interfacial moment, and the mechanism illustration from\nthe Supplementary Material should be moved to the main text.\nResponse: Following this suggestion, we have highlighted the interfaces in Figure 1c\nin red color and restructured Figures 3 and 4 in the main text to better illustrate the\nswitching process.\nThe experimental results are interesting, but I cannot recommend publication in Nature\nCommunications until these issues are fully addressed.\nResponse: We thank the Reviewer again for the referential comments, which have\nsignificantly enhanced the quality of our work.\nSummary of the changes made in the revised manuscript\n1. In page 1, the title of “Collinear Antiferromagnetic Tunnel Junctions Implemented\nin Van der Waals Heterostructures” was changed to “Interface-Controlled\nAntiferromagnetic Tunnel Junctions based on a metallic van der Waals A-type\nAntiferromagnet”.\n2. In page 6, first paragraph, we added “The Interface-assisted Néel vector switching\nis governed by the competition between magnetocrystalline anisotropy energy,\nAFM exchange energy, Zeeman energy, and domain wall dynamics. Although the\ntwo FCGT electrodes in device D1 have identical nominal thicknesses, differences\nin their local environments—arising from proximity coupling to distinct substrate\nor capping layers—and variations in defect distributions can lead to different\neffective anisotropies and domain pinning strengths, resulting in distinct critical\nswitching fields. This asymmetry enables the observation of TMR.”\n3. In page 9, paragraph 3, the sentence of “A promising avenue for future exploration\nwould be the interface-assisted spin-orbit torque manipulation of Néel vectors for\nall-electric AFM spintronic devices” was changed to “A promising avenue for\nfuture exploration would be to use ultrafast optical method to directly detect the\nNéel vectors switching to study AFM dynamics and to manipulate the Néel vectors\nwith the interface-assisted spin-orbit torque for all-electric AFM spintronic\ndevices”.\n4. In pages 14 and 15, we restructured Figures 3 and 4 to better illustrate the switching\nprocess.\n5. In supplementary material, we added new figures as Figure S9 to demonstrate the\nfield-cooling results for the independent FCGT.\n6. In the manuscript and supplementary material, the figure numbering has been\nadjusted to accommodate the inclusion of additional figures.\n7. Other minor changes are marked by blue fonts in the manuscript."}, {"round": 2, "reviewer_comments": {"reviewer_2": "Authors have answered my questions well. I recommend its publication now."}, "author_response": "Response: We appreciate the Reviewer’s recommendation to publish our manuscript."}]

Decision letter