作成者： DUTTAGUPTA SAMIK（東北大CSIS）

2021年度 提案書 （Web公開用）

研究プロジェクト名: Topological spin textures in 2D van der Waals(vdW) magnet/heavy-metal structures
概要： Two-dimensional (2D) van der Waals (vdW) materials have recently gathered considerable attention owing to theirprospect for low-power spintronic devices and quantum information science applications. The presence of strong spinorbit coupling interactions leading to stabilization of long-range magnetic order down to the atomic limit, and flexibility
with various elements and structures provides a fertile opportunity for the realization of emergent 2D magnetic texturebased novel spintronic devices. Clarification of the underlying physics governing the manifestation of exotic spin texturesin 2D magnetic heterostructures and the possibility to tailor their properties through material and interface engineering
is expected to enunciate deeper understanding of magnetism at low dimensions and pave the way for utilization of 2Dmagnets for conventional and unconventional computing devices.

コアメンバー： DuttaGupta Samik (CSIS),Roy Chowdhury Rajeswari (IISERB), TretiakovOleg (UNSW), Singh Ravi Prakash (IISERB), Ieda Jun’ichi (JAEA), Fukami Shunsuke (RIEC)
期 待 さ れ る 研 究 成 果 ： Previously, ourexperimental results have shown the existence ofunconventional magnetic textures in singlecrystalline bulk 2D magnet (Fig. 1(a)). We havealso shown exceptional temperature insensitivity,and controllable size by breaking crystal inversion
symmetry. Magneto-optical and electronic
measurements in vdW magnet/heavy metalstructures (Fig. 1(b)) and its comparison to singlecrystalline bulk is expected to provide
considerable insights into the underlying physics,
show new directions towards utilization ofemergent magnetic textures for spintronic devices.
The obtained results are also prospective for thedevelopment of magnetic texture based
spintronic devices for unconventional computing.

Bulk vdW magnet(our work)

20 µm(a)This Research
Exfoliated vdW magnet(b)Figure 1: (a) Magneto-optic Kerr effect (MOKE) imaging of unconventional
magnetic texture in a single-crystalline bulk vdW magnet Fe3GeTe2 (our work)(at T = 50 K). Grey (black) areas correspond to up (down) configurations ofmagnetic domains. (b) Schematic diagram of the proposed 2D vdW magnet/
heavy metal (HM) structure to be investigated in this study. Inset in (b) shows
the optical microscope image of an isolated vdW ferromagnetic Fe3GeTe2
flake on substrate, achieved through mechanical exfoliation technique.

2021年度 報告書 （Web公開用）

作成者： DUTTAGUPTA SAMIK（東北大CSIS）

研究プロジェクト名： Topological spin textures in 2D van der Waals(vdW) magnet/heavy‐metal structures

Bulk vdW magnet(our previous work)

20 µm(a)432
14

XY ( cm)

研究成果（実施状況）：Using the vdW magnet
Fe3GeTe2 (FGT, hereafter), we have demonstrated
the existence of unconventional spin textures in acentrosymmetric structure (Fig. 1(a)) [1,2]. In thisresearch, we have optimized and fabricated FGTand FGT/heavy metal structures using various
device fabrication procedures. Interestingly, theunderlying emergent magnetic field is virtuallyinsensitive to FGT thickness (~ 50 nm) suggesting
the possibility of an unconventional magnetic
ground state even at reduced dimensions (Fig.
1(b)). Investigations concerning the effect ofelectrical current on the spin textures andemergent magnetic field under varying thickness
are currently under investigation.

Emergent Magnetic Field (T)概要： Two‐dimensional (2D) van der Waals (vdW) materials have recently gathered significant attention owing to their prospect
for low‐power spintronic devices and quantum information science applications. The presence of strong spin‐orbit couplinginteractions leading to stabilization of long‐range magnetic order down to the atomic limit, and flexibility with various elements
and structures provides a fertile opportunity for the realization of emergent 2D magnetic texture‐based novel spintronic devices.
Clarification of the underlying physics governing the manifestation of exotic spin textures in 2D magnetic heterostructures and thepossibility to tailor their properties through material and interface engineering is expected to enunciate deeper understanding ofmagnetism at low dimensions and pave the way for utilization of 2D magnets for conventional and unconventional computingdevices.

0-2-4-400(b)

FGT

2-20

0H (T)

24Bulk200 400 600 10000
Thickness (nm)Figure 1: (a) Magneto-optic Kerr effect (MOKE) imaging of unconventional magnetic
texture in a single-crystalline bulk vdW magnet Fe3GeTe2 (our work) (at T = 50 K).
Grey (black) areas correspond to up (down) configurations of magnetic domains. (b)Experimental results of emergent magnetic field as a function of FGT thickness in
exfoliated devices. Inset in (b) shows the experimental results of transverse resistivity(ρXY) versus applied magnetic field (H) for bulk FGT at T = 100 K. The black arrow in
the inset indicates the definition of the emergent magnetic field from ρXY vs H
measurements.

主要発表論文等： [1] R. Roy Chowdhury, S. DuttaGupta et al., Sci. Rep. 11, 14121 (2021).
[2] R. Roy Chowdhury, S. DuttaGupta et al., Phys. Rev. Mater. 6, 014002 (2022).