Two-dimensional centrosymmetrical antiferromagnets for spin photogalvanic devices

Peng Jiang,Hua Hao,Xixi Tao,Yushen Liu,Xiaohong Zheng,Zhi Zeng

doi:10.1038/s41534-021-00365-7

Abstract

Spin-dependent photogalvanic effect (PGE) in low-dimensional magnetic systems has recently attracted intensive attention. Based on first-principle transport calculations and symmetry analyses, we propose a robust scheme to generate pure spin current by PGE in centrosymmetric materials with spin polarization antisymmetry. As a demonstration, the idea is successfully applied to a photoelectric device constructed with a zigzag graphene nanoribbon (ZGNR), which has intrinsic antiferromagnetic coupling between the two edges and spin degenerate band structure. It suggests that spin splitting is not a prerequisite for pure spin current generation. More interestingly, by further introducing external transverse electric fields to the two leads to lift the spin degeneracy, the device may behave multifunctionally, capable of producing fully spin-polarized current or pure spin current, depending on whether the fields in the two leads are parallel or antiparallel. Very importantly, our scheme of pure spin current generation with PGE is not limited to ZGNR and can be extended to other two-dimensional (2D) centrosymmetric magnetic materials with spin polarization antisymmetry, suggesting a promising category of 2D platforms for PGE-based pure spin current generation.

Highlights

The photogalvanic effect (PGE), characterized by a finite direct electric current produced in materials lacking space inversion symmetry by the light illumination without any applied bias voltage, has great potential in the field of the photoelectric devices due to the great advantages of its self-powered function[1,2,3,4,5,6,7,8,9]
We theoretically propose a class of spin photogalvanic devices for pure spin current generation with PGE based on AFM semiconductors, in which the whole structure holds spatial inversion symmetry while the real-space charge distribution of neither the spin-up state nor the spin-down state holds spatial inversion symmetry
We find that, when two antiparallel electric fields with the same magnitude are applied to the two leads, pure spin current can still be robustly generated by PGE due to the preservation of spin density antisymmetry

Summary

INTRODUCTION

The photogalvanic effect (PGE), characterized by a finite direct electric current produced in materials lacking space inversion symmetry by the light illumination without any applied bias voltage, has great potential in the field of the photoelectric devices due to the great advantages of its self-powered function[1,2,3,4,5,6,7,8,9]. A natural question to ask is that, are there schemes for pure spin current generation with PGE that are not limited to any particular photon energy or polarization angle, not limited to materials with spin splitting band structures, and demand no external magnetic fields?. We demonstrate that pure spin current generation scheme with PGE proposed in this work can be extended to other antiferromagnets with spatial inversion symmetry and bilayer 2H-VSe2 is provided as example of 2D Atype van der Waals (vdWs) antiferromagnets for the extension

RESULTS AND DISCUSSION

METHODS

CODE AVAILABILITY