Strain induced phase transition from antiferromagnet to altermagnet

TL;DR

This paper demonstrates a strain-induced phase transition from antiferromagnetic to altermagnetic in ReO$_2$, revealing a pathway for controlled magnetic phase switching with potential spintronic applications.

Contribution

It introduces a novel method to induce altermagnetism via strain in ReO$_2$, combining symmetry analysis and ab-initio calculations to show the transition and associated electronic changes.

Findings

Strain causes ReO$_2$ to transition from antiferromagnetic to altermagnetic phase.

The transition lifts Kramer's degeneracy and induces a metal-insulator change.

Distinct spin-polarized spectral functions are predicted for experimental detection.

Abstract

The newly discovered altermagnets are unconventional collinear compensated magnetic systems, exhibiting even (d, g, or i-wave) spin-polarization order in the band structure, setting them apart from conventional collinear ferromagnets and antiferromagnets. Altermagnets offer advantages of spin polarized current akin to ferromagnets, and THz functionalities similar to antifferomagnets, while introducing new novel effects like spin-splitter currents. A key challenge for future applications and functionalization of altermagnets, is to demonstrate controlled transitioning to the altermagnetic phase from other conventional phases in a single material. Here we prove a viable path towards overcoming this challenge through a strain-induced transition from an antiferromagnetic to an altermagnetic phase in ReO$_2$. Combining spin group symmetry analysis and \textit{ab-initio} calculations, we demonstrate that under compressive strain ReO$_2$ undergoes such transition, lifting the Kramer's degeneracy of the band structure of the antiferromagnetic phase in the non-relativistic regime. In addition, we show that this magnetic transition is accompanied by a metal insulator transition, and calculate the distinct spin polarized spectral functions of the two phases, which can be detected in angle resolved photo-emission spectroscopy experiments.