Reversible giant out-of-plane Rashba effect in two-dimensional Ga$XY$ ($X$= Se, Te; $Y$= Cl, Br, I) compounds for persistent spin helix

Abstract

The coexistence of ferroelectricity and spin-orbit coupling (SOC) in noncentrosymmetric systems may allow for a nonvolatile control of spin degrees of freedom by switching the ferroelectric polarization through the well-known ferroelectric Rashba effect (FRE). Although the FER has been widely observed for bulk ferroelectric systems, its existence in two-dimensional (2D) ferroelectric systems is still very rarely discovered. Based on first-principles calculations, supplemented with $\vec{k}\cdot \vec{p}$ analysis, we report the emergence of the FRE in the Ga$XY$ ($X$= Se, Te; $Y$= Cl, Br, I) monolayer compounds, a new class of 2D materials having in-plane ferroelectricity. Due to the large in-plane ferroelectric polarization, a giant out-of-plane Rashba effect is observed in the topmost valence band, producing unidirectional out-of-plane spin textures in the momentum space. Importantly, such out-of-plane spin textures, which can host a long-lived helical spin mode known as a persistent spin helix, can be fully reversed by switching the direction of the in-plane ferroelectric polarization. Thus, our findings can open avenues for interplay between the unidirectional out-of-plane Rashba effect and the in-plane ferroelectricity in 2D materials, which is useful for efficient and non-volatile spintronic devices.

5 Figures, submitted

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Cited by in corpus (6)

• Full-zone Persistent Spin Textures with Giant Spin Splitting in Two-dimensional Group IV-V Compounds
• Anisotropic Rashba splitting dominated by out-of-plane spin polarization in two-dimensional Janus $X{A}_{2}Y$ ($A$= Si, Sn, Ge; $X,Y$= Sb, Bi) with surface imperfection
• Reversible canted persistent spin textures with large spin splitting in two-dimensional ferroelectric bilayer WTe${}_2$
• Emergence of Rashba spin valley state in two-dimensional strained bismuth oxychalcogenides Bi${}_2$O${}_2$Se
• Persistent Spin Textures in Nonpolar Chiral Systems
• Kondo effect in a two-dimensional electron gas in the Persistent Spin Helix regime