Intrinsic Valley-Related Multiple Hall Effect in 2D Organometallic Lattice

TL;DR

This paper reports the discovery of an intrinsic valley-related multiple Hall effect in a 2D organometallic NbTa-benzene lattice, revealing new fundamental physics and potential for novel device applications.

Contribution

It introduces the first intrinsic valley-related multiple Hall effect in a 2D organometallic lattice, combining valley polarization, quantum anomalous Hall effect, and strain tunability.

Findings

Large spontaneous valley polarization in NbTa-benzene.

Intrinsic band inversion at one valley leads to quantum anomalous Hall effect.

Strain can switch between valley, ferrovalley, and quantum anomalous Hall phases.

Abstract

Valley-related multiple Hall effect in 2D lattice is a fundamental transport phenomenon in the fields of condensed-matter physics and material science. So far, most proposals for its realization are limited to toy models or extrinsic effects. Here, based on tight-binding model and first-principles calculations, we report the discovery of intrinsic valley-related multiple Hall effect in 2D organometallic lattice of NbTa-benzene. Protected by the breaking of both time-reversal and inversion symmetry, NbTa-benzene exhibits large valley polarization spontaneously in both the conduction and valence bands, guaranteeing the anomalous valley Hall effect. Simultaneously, because of the exchange interaction and strong spin-orbit coupling, intrinsic band inversion occurs at one valley, which ensures the valley-polarized quantum anomalous Hall effect, thus presenting the extraordinary valley-related multiple Hall effect in nature. In addition, it can be transformed into the phase with ferrovalley or quantum anomalous Hall effect solely through strain engineering. These insights not only are useful for the fundamental research in valley-related physics, but also enable a wide range of novel device applications.