Predictable gate-field control of spin in altermagnets with spin-layer coupling

TL;DR

This paper introduces a new method for controlling electron spin in altermagnets using electric fields without relying on spin-orbit coupling, enabling reversible spin manipulation for advanced spintronic devices.

Contribution

The study proposes a novel mechanism utilizing valley-mediated spin-layer coupling in 2D altermagnets for electric control of spin without spin-orbit coupling dependence.

Findings

Significant spin splitting up to 123 meV in monolayer Ca(CoN)$_2$ with a 0.2 eV/Å gate field.

Predictable, continuous, and reversible spin control demonstrated.

Potential for high-performance spintronic devices with switchable spin and valley currents.

Abstract

Spintronics, a technology harnessing electron spin for information transmission, offers a promising avenue to surpass the limitations of conventional electronic devices. While the spin directly interacts with the magnetic field, its control through the electric field is generally more practical, and has become a focal point in the field of spintronics. Current methodologies for generating spin polarization via an electric field generally necessitate spin-orbit coupling. Here, we propose an innovative mechanism that accomplishes this task without dependence on spin-orbit coupling. Our method employs two-dimensional altermagnets with valley-mediated spin-layer coupling (SLC), in which electronic states display symmetry-protected and valley-contrasted spin and layer polarization. The SLC facilitates predictable, continuous, and reversible control of spin polarization using a gate electric field. Through symmetry analysis and ab initio calculations, we pinpoint high-quality material candidates that exhibit SLC. We ascertain that applying a gate field of $0.2$ eV/\AA~ to monolayer Ca(CoN)$_2$ can induce significant spin splitting up to 123 meV. As a result, perfect and switchable spin/valley-currents, and substantial tunneling magnetoresistance can be achieved in these materials using only a gate field. These findings provide new opportunities for generating predictable spin polarization and designing novel spintronic devices based on coupled spin, valley and layer physics.