Possibility of regulating valley-contrasting physics and topological properties by ferroelectricity in functionalized...

A two-dimensional (2D) multifunctional material, which couples multiple physical properties together, is both fundamentally intriguing and practically appealing. Here, based on first-principles calculations and tight-binding (TB) model analysis, the possibility of regulating the valley-contrasting physics and nontrivial topological properties via ferroelectricity is investigated in monolayer AsCH₂OH. Reversible electric polarization is accessible via the rotation operation on the ligand. The broken inversion symmetry and the spin-orbit coupling (SOC) would lead to valley spin splitting, spin-valley coupling and valley-contrasting Berry curvature. More importantly, the reversal of electric polarization can realize the nonvolatile control of valley-dependent properties. Besides, the nontrivial topological state is confirmed in the monolayer AsCH₂OH, which is robust against the rotation operation on the ligand. The magnitude of polarization, valley spin splitting and bulk band gap can be effectively modulated by the biaxial strain. The H-terminated SiC is demonstrated to be an appropriate candidate for encapsulating monolayer AsCH₂OH, without affecting its exotic properties. These findings provide insights into the fundamental physics for the coupling of the valley-contrasting phenomenon, topological properties and ferroelectricity, and open avenues for exploiting innovative device applications.