Ferroelectrically Switchable Half-Quantized Hall Effect.

Abstract

Integrating ferroelectricity, antiferromagnetism, and topological quantum transport within a single material is rare but crucial for developing next-generation quantum devices. Here, we propose a multiferroic heterostructure consisting of an antiferromagnetic MnBi₂Te₄ bilayer and an Sb₂Te₃ film is able to harbor the half-quantized Hall (HQH) effect with a ferroelectrically switchable Hall conductivity of ± <i>e</i>²/2<i>h</i>. We first show that, in the energetically stable configuration, the antiferromagnetic MnBi₂Te₄ bilayer opens a gap in the top surface bands of Sb₂Te₃ through the proximity effect, while its bottom surface bands remain gapless; consequently, an HQH conductivity of <i>e</i>²/2<i>h</i> can be sustained clockwise or counterclockwise, depending on the antiferromagnetic configuration of the MnBi₂Te₄. Remarkably, when interlayer sliding is applied within the MnBi₂Te₄ bilayer, its electric polarization direction associated with parity-time reversal symmetry breaking is reversed, accompanied by a reversal of the HQH conductivity. The proposed approach offers a powerful route to control topological quantum transport in antiferromagnetic materials by ferroelectricity.