Tunable valley and spin splittings in $\rm VSi_2N_4$ bilayer

TL;DR

This study demonstrates that electric fields can effectively tune valley and spin splittings in VSi2N4 bilayers, enabling energy-efficient control of electronic properties for advanced device applications.

Contribution

First-principles calculations reveal tunable valley and spin splittings in VSi2N4 bilayers via electric fields, depending on stacking and magnetic coupling, advancing control of electronic degrees of freedom.

Findings

Degeneracy splittings are highly tunable with electric fields.

Different stacking orders and magnetic couplings produce varied valley and spin configurations.

Electric control enables selective anomalous Hall currents.

Abstract

The control and manipulation of the valley and spin degrees of freedom have received great interests in fundamental studies and advanced information technologies. Compared with magnetic means, it is highly desirable to realize more energy-efficient electric control of valley and spin. Using the first-principles calculations, we demonstrate tunable valley and spin degeneracy splittings in $\rm VSi_2N_4$ bilayers, with the aid of the layered structure and associated electric control. Depending on different interlayer magnetic couplings and stacking orders, the $\rm VSi_2N_4$ bilayers exhibit a variety of combinations of valley and spin degeneracies. Under the action of a vertical electric field, the degeneracy splittings become highly tunable for both the sign and magnitude. As a result, a series of anomalous Hall currents can be selectively realized with varied indices of valley and spin. These intriguing features offer a practical way for designing energy-efficient devices based on the couplings between multiple electronic degrees of freedom.