Robust spin splitting and fermiology in a layered altermagnet

TL;DR

This paper demonstrates the induction of a robust altermagnetic phase in a layered material through cobalt intercalation, revealing spin-dependent properties and electronic structures that could advance spintronic applications.

Contribution

It introduces a method to stabilize altermagnetism in layered materials and provides experimental and theoretical evidence of its electronic properties and degeneracy lifting.

Findings

Successful stabilization of altermagnetism in 2H-NbSe2 via cobalt intercalation

Observation of Kramers degeneracy lifting in the altermagnetic phase

Identification of a low-temperature phase with distinct electronic origin

Abstract

Altermagnetism defies conventional classifications of collinear magnetic phases, standing apart from ferromagnetism and antiferromagnetism with its unique combination of spin-dependent symmetries, net-zero magnetization, and anomalous Hall transport. Although altermagnetic states have been realized experimentally, their integration into functional devices has been hindered by the structural rigidity and poor tunability of existing materials. First, through cobalt intercalation of the superconducting 2H-NbSe$_2$ polymorph, we induce and stabilize a robust altermagnetic phase and using both theory and experiment, we directly observe the lifting of Kramers degeneracy. Additionally, we present spectroscopic insight into a previously hinted low-temperature phase, and provide evidence of its electronic origin. While shedding light on overlooked aspects of altermagnetism, these findings open pathways to spin-based technologies and lay a foundation for advancing the emerging field of altertronics.