Layer Hall Effect in Multiferroic Two-Dimensional Materials.

Feng, Yangyang; Dai, Ying; Huang, Baibiao; Kou, Liangzhi; Ma, Yandong · Nano Lett · 2023

basic_science · Level V

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Abstract

The layer Hall effect (LHE) is of fundamental and practical importance in condensed-matter physics and material science; however, it was rarely observed and usually based on the paradigms of persistent electric field and sliding ferroelectricity. Here, a new mechanism of LHE is proposed by coupling layer physics with multiferroics using symmetry analysis and a low-energy <i><b>k·p</b></i> model. Due to time-reversal symmetry breaking and valley physics, the Bloch electrons on one valley will be subject to a large Berry curvature. This combined with inversion symmetry breaking gives rise to layer-polarized Berry curvature and can force the electrons to deflect in one direction of a given layer, thereby generating the LHE. We demonstrate that the resulting LHE is ferroelectrically controllable and reversible. Using first-principles calculations, this mechanism and predicted phenomena are verified in the multiferroic material of bilayer Co<sub>2</sub>CF<sub>2</sub>. Our finding opens a new direction for LHE and 2D materials research.