Rashba-like spin splitting along three momentum directions in trigonal layered PtBi2

Ya Feng,Baojie Feng,Masashi Arita,Harald O Jeschke,Xianxin Wu,Shaolong He,Qi Jiang,Wenjing Liu,Kenya Shimada,Ronny Thomale,Youguo Shi,Eike F Schwier,Xiufu Yang,Meng Yang,Shan Qiao,Shaozhu Xiao,Tao Xu

doi:10.1038/s41467-019-12805-2

Abstract

Spin-orbit coupling (SOC) has gained much attention for its rich physical phenomena and highly promising applications in spintronic devices. The Rashba-type SOC in systems with inversion symmetry breaking is particularly attractive for spintronics applications since it allows for flexible manipulation of spin current by external electric fields. Here, we report the discovery of a giant anisotropic Rashba-like spin splitting along three momentum directions (3D Rashba-like spin splitting) with a helical spin polarization around the M points in the Brillouin zone of trigonal layered PtBi2. Due to its inversion asymmetry and reduced symmetry at the M point, Rashba-type as well as Dresselhaus-type SOC cooperatively yield a 3D spin splitting with αR ≈ 4.36 eV Å in PtBi2. The experimental realization of 3D Rashba-like spin splitting not only has fundamental interests but also paves the way to the future exploration of a new class of material with unprecedented functionalities for spintronics applications.

Highlights

Spin-orbit coupling (SOC) has gained much attention for its rich physical phenomena and highly promising applications in spintronic devices
The Rashba-type SOC is usually caused by structure inversion asymmetry (SIA) which stems from the inversion asymmetry of the confining potential[2,3]
We report the discovery of a giant anisotropic 3D Rashba-like spin splitting directly observed by spin-angle-resolved photoemission spectroscopy (ARPES) in a binary compound: PtBi2

Summary

Introduction

Spin-orbit coupling (SOC) has gained much attention for its rich physical phenomena and highly promising applications in spintronic devices. The Rashba-type SOC in systems with inversion symmetry breaking is attractive for spintronics applications since it allows for flexible manipulation of spin current by external electric fields. The present material realizations for potential spintronics applications are based on spin–orbit coupling (SOC)[1,2], which is a relativistic interaction of the electron spin with its motion in a potential It allows for the removal of spin degeneracy in a nonmagnetic material without the use of an external magnetic field. It originates from lack of inversion symmetry in the bulk and yields Dresselhaus-type SOC5,6 In many materials, these two kinds of SOC couple together, resulting in an anisotropy of spin splitting. The reduced point group symmetry at M along with the BIA allow the Dresselhaus-type and Rashba-type SOC terms to cooperatively yield a large 3D anisotropic spin splitting with a helical texture around the M point

Methods

Results

Conclusion