Observation of Spin-Momentum-Layer Locking in a Centrosymmetric Crystal

Ke Zhang, Shixuan Zhao, Zhanyang Hao, Shiv Kumar, Eike. F. Schwier, Yingjie Zhang, Hongyi Sun, Yuan Wang, Yujie Hao, Xiaoming Ma, Cai Liu, Le Wang, Xiaoxiao Wang, Koji Miyamoto, Taichi Okuda, Chang Liu, Jiawei Mei, Kenya Shimada, Chaoyu Chen, and Qihang Liu

Phys. Rev. Lett. 127, 126402 – Published 14 September 2021

Abstract

The spin polarization in nonmagnetic materials is conventionally attributed to the outcome of spin-orbit coupling when the global inversion symmetry is broken. The recently discovered hidden spin polarization indicates that a specific atomic site asymmetry could also induce measurable spin polarization, leading to a paradigm shift in research on centrosymmetric crystals for potential spintronic applications. Here, combining spin- and angle-resolved photoemission spectroscopy and theoretical calculations, we report distinct spin-momentum-layer locking phenomena in a centrosymmetric, layered material, BiOI. The measured spin is highly polarized along the Brillouin zone boundary, while the same effect almost vanishes around the zone center due to its nonsymmorphic crystal structure. Our work demonstrates the existence of momentum-dependent hidden spin polarization and uncovers the microscopic mechanism of spin, momentum, and layer locking to each other, thus shedding light on the design metrics for future spintronic materials.

Received 18 February 2021
Accepted 30 July 2021

DOI:https://doi.org/10.1103/PhysRevLett.127.126402

Physics Subject Headings (PhySH)

Dresselhaus coupling Rashba coupling

Angle-resolved photoemission spectroscopy Density functional theory

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Ke Zhang ^1,*, Shixuan Zhao^2,*, Zhanyang Hao^2,*, Shiv Kumar³, Eike. F. Schwier ^3,6,7, Yingjie Zhang², Hongyi Sun², Yuan Wang², Yujie Hao ², Xiaoming Ma², Cai Liu ², Le Wang², Xiaoxiao Wang³, Koji Miyamoto³, Taichi Okuda³, Chang Liu ², Jiawei Mei², Kenya Shimada ^3,†, Chaoyu Chen ^2,‡, and Qihang Liu ^2,4,5,§

¹Department of Physical Science, Graduate School of Science, Hiroshima University, Hiroshima 739-0046, Japan
²Shenzhen Institute for Quantum Science and Technology and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
³Hiroshima Synchrotron Radiation Center, Hiroshima University, Hiroshima 739-0046, Japan
⁴Guangdong Provincial Key Laboratory for Computational Science and Material Design, Southern University of Science and Technology, Shenzhen 518055, China
⁵Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen 518055, China
⁶Experimentelle Physik VII, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
⁷Würzburg-Dresden Cluster of Excellence ct.qmat, Germany

^*These authors contributed equally to this work.
^†kshimada@hiroshima-u.ac.jp
^‡chency@sustech.edu.cn
^§liuqh@sustech.edu.cn

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Issue

Vol. 127, Iss. 12 — 17 September 2021

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