Spontaneous valley polarization and valley-nonequilibrium quantum anomalous Hall effect in Janus monolayer ScBrI.

Nanoscale

School of Physics and Physical Engineering, Qufu Normal University, Qufu, Shandong, 273100, People's Republic of China.

Published: May 2023

AI Article Synopsis

  • The research explores the intersection of topology and ferrovalley (FV) in semiconductor systems, highlighting the unique properties of the stable intrinsic FV ScBrI material.
  • By utilizing Monte Carlo simulations and first-principles calculations, the study predicts high Curie temperatures and significant valley polarization in the ScBrI monolayer, with spontaneous polarization observed.
  • It also discusses how strain engineering can toggle between different electronic states, including valley-nonequilibrium quantum anomalous Hall effect (VQAHE), emphasizing the potential of ScBrI for applications in advanced electronics and nanodevices.

Article Abstract

Topology and ferrovalley (FV) are two essential concepts in emerging device applications and the fundamental research field. To date, relevant reports are extremely rare about the coupling of FV and topology in a single system. By Monte Carlo (MC) simulations and first-principles calculations, a stable intrinsic FV ScBrI semiconductor with high Curie temperature () is predicted. Because of the combination of spin-orbital coupling (SOC) and exchange interaction, the Janus monolayer ScBrI shows a spontaneous valley polarization of 90 meV, which is located in the top valence band. For the magnetization direction perpendicular to the plane, the changes from FV to half-valley-metal (HVM), to valley-nonequilibrium quantum anomalous Hall effect (VQAHE), to HVM, and to FV can be induced by strain engineering. It is worth noting that there are no particular valley polarization and VQAHE states for in-plane (IP) magnetic anisotropy. By obtaining the real magnetic anisotropy energy (MAE) under different strains, due to spontaneous valley polarization, intrinsic out-of-plane (OOP) magnetic anisotropy, a chiral edge state, and a unit Chern number, the VQAHE can reliably appear between two HVM states. The increasing strains can induce VQAHE, which can be clarified by a band inversion between d/d and d orbitals, and a sign-reversible Berry curvature. Once synthesized, the Janus monolayer ScBrI would find more significant applications in topological electronic, valleytronic, and spintronic nanodevices.

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Source
http://dx.doi.org/10.1039/d2nr07221aDOI Listing

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