Electrically switchable hidden spin polarization in antiferroelectric crystals

TL;DR

This paper introduces antiferroelectric crystals as a new class of materials capable of exhibiting strong hidden spin polarization, which can be electrically switched to control spin properties nonvolatily.

Contribution

It proposes a new class of antiferroelectric crystals with switchable hidden spin polarization, supported by first-principles calculations on a novel 2D material, QL-LiBiO$_2$.

Findings

Strong HSP predicted in 2D QL-LiBiO$_2$

Reversible switching between AFE and FE phases

Electric polarization and spin polarization tunability

Abstract

Hidden spin polarization (HSP) emerges in centrosymmetric crystals where visible spin splittings in the real space can be observed because of the lack of inversion symmetry in each local sector. Starting from tight-binding models, we introduce nonsymmorphic antiferroelectric (AFE) crystals as a new class of functional materials that can exhibit strong local spin polarization. Such AFE crystals can be basically classified as in-plane and out-of-plane AFE configurations, and can be reversibly switched to the ferroelectric phase by an electric field to manifest global spin splittings, enabling a nonvolatile electrical control of spin-dependent properties. Based on first-principle calculations, we predict the realization of strong HSP in the AFE phase of a newly-discovered two-dimensional materials, quintuple-layer (QL) LiBiO$_2$. Furthermore, the spontaneous electric polarization ($\sim$ 0.3 nC/m) and the transition barrier as well as the tunable spin polarization of QL-LiBiO$_2$ are discussed.