Valley-dependent topological phase transition and quantum anomalous valley Hall effect in single-layer RuClBr

Hao Sun, Sheng-Shi Li, Wei-xiao Ji, and Chang-Wen Zhang
Phys. Rev. B 105, 195112 – Published 9 May 2022
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Abstract

Quantum anomalous valley Hall effect (QAVHE), which combines both the features of QAHE and AVHE, is both fundamentally intriguing and practically appealing, but is experimentally challenging to realize in two-dimensional (2D) intrinsic magnetic materials to date. Here, based on first-principles calculations with the density functional theory +U approach, we predicted the electronic correlation-driven valley-dependent quantum phase transition from ferrovalley (FV) to half-valley-semiconductor (HVS) to QAVHE to HVS to FV phase in single-layer RuClBr. Remarkably, the QAVHE phase with an integer Chern number (C=1) and chiral spin-valley locking, which is induced by sign-reversible Berry curvature or band inversion between dxy/dx2y2 and dz2 orbitals, can achieve complete spin and valley polarizations for low-dissipation electronics devices. We also find that the electron valley polarization can be switched by reversing magnetization direction, providing a route of magnetic control of the valley degree of freedom. An effective k·p model is proposed to clarify valley-dependent quantum phenomena. Additionally, electronic correlation has an important effect on the variations of the Curie temperature of single-layer RuClBr. These findings shed light on the possible role of correlation effects on valley-dependent physics in 2D materials and open alternative perspectives for multifunctional spin-valley quantum devices in valleytronics.

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  • Received 2 March 2022
  • Revised 21 April 2022
  • Accepted 26 April 2022

DOI:https://doi.org/10.1103/PhysRevB.105.195112

©2022 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Hao Sun, Sheng-Shi Li, Wei-xiao Ji*, and Chang-Wen Zhang

  • School of Physics and Technology, Institute of Spintronics, University of Jinan, Jinan, Shandong 250022, People's Republic of China

  • *sps_jiwx@ujn.edu.cn
  • ss_zhangchw@ujn.edu.cn

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Issue

Vol. 105, Iss. 19 — 15 May 2022

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