Twisted Magnetic Van der Waals Bilayers: An Ideal Platform for Altermagnetism

TL;DR

This paper presents a universal method to induce and control altermagnetism in 2D van der Waals materials through twisting, enabling tailored magnetic properties and enhanced spin current manipulation.

Contribution

The authors introduce a general twisting technique to generate and tune altermagnetism in any 2D MvdW material, expanding the possibilities for spintronic applications.

Findings

Twisted bilayers can achieve in-plane 2-fold rotational symmetry inducing altermagnetism.

The approach allows tailoring of altermagnetic types such as d-wave, g-wave, and i-wave.

Tuning twist angle and Fermi level in VOBr yields a giant spin Hall angle.

Abstract

We introduce a universal methodology for generating and manipulating altermagnetism in two-dimensional (2D) magnetic van der Waals (MvdW) materials through twisting. We find that a key in-plane 2-fold rotational operation can be achieved in a twisted bilayer of any 2D MvdW material, which takes one of all five 2D Bravais lattices, thereby inducing altermagnetism. By choosing the constituent MvdW monolayer with specific symmetry, our approach can tailor altermagnetism of any type, such as $d$-wave, $g$-wave, and $i$-wave. Furthermore, the properties of our twisted altermagnetic materials can be easily engineered. Taking a transition-metal oxyhalide VOBr as an example, we find that by tuning the twist angle and Fermi level a giant spin Hall angle can be obtained, much larger than the experimentally reported. This approach establishes a general, robust, and adjustable platform to explore altermagnetism, and provides a new efficient way to generate and manipulate the spin current.