Controllable Domain Walls in Two-Dimensional Ferromagnetic Material Fe3GeTe2 Based on the Spin-Transfer Torque Effect

Ke Pei; Shanshan Liu; Liting Yang; Enze Zhang; Ruixuan Zhang; Chendi Yang; Linfeng Ai; Zihan Li; Faxian Xiu; Renchao Che

doi:10.1021/acsnano.1c06361

Controllable Domain Walls in Two-Dimensional Ferromagnetic Material Fe₃GeTe₂ Based on the Spin-Transfer Torque Effect

ACS Nano. 2021 Dec 28;15(12):19513-19521. doi: 10.1021/acsnano.1c06361. Epub 2021 Dec 13.

Authors

Ke Pei¹, Shanshan Liu^{2

3}, Liting Yang¹, Enze Zhang^{2

3}, Ruixuan Zhang¹, Chendi Yang¹, Linfeng Ai^{2

3}, Zihan Li^{2

3}, Faxian Xiu^{2

3

4}, Renchao Che¹

Affiliations

¹ Laboratory of Advanced Materials, Department of Materials Science and Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200438, China.
² State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
³ Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China.
⁴ Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.

PMID: 34894654
DOI: 10.1021/acsnano.1c06361

Abstract

Recently, two-dimensional magnetic material has attracted attention worldwide due to its potential application in magnetic memory devices. The previous concept of domain walls driven by current pulses is a disordered motion. Further investigation of the mechanism is urgently lacking. Here, Fe₃GeTe₂, a typical high-Curie temperature (T_C) two-dimensional magnetic material, is chosen to explore the magnetic domain dynamics by in situ Lorentz transmission electron microscopy experiments. It has been found that the stripe domain could be driven, compressed, and expanded by the pulses with a critical current density. Revealed by micromagnetic simulations, all the domain walls cannot move synchronously due to the competition between demagnetization energy and spin-transfer torque effect. In consideration of the reflection of high-frequency pulses, the disordered motion could be well explained together. The multiple stable states of the magnetic structure due to the weak exchange interaction in a two-dimensional magnet provides complex dynamic processes. Based on plenty of experiments, a cluster of domain walls could be more steady and move more synchronously under the drive of pulse current. The complication of domain wall motions presents a challenge in race track memory devices and two-dimensional magnetic material will be a better choice for application research.

Keywords: 2D ferromagnetic materials; critical current density; magnetic domain wall; micromagnetic simulation; nonuniform motion; spin-transfer torque effect.