Atomic-scale visualization of d-wave altermagnetism

TL;DR

This study provides the first atomic-scale real-space visualization of altermagnetism in CsV2Se2O using scanning tunnelling microscopy, revealing symmetry breaking and spin order.

Contribution

It presents direct real-space evidence of altermagnetism, a novel magnetic phase, using intrinsic spin defects as probes at atomic resolution.

Findings

Visualization of unidirectional electronic patterns linked to symmetry breaking

Observation of elliptical charging rings tied to alternating spin textures

Detection of opposite spins and long-range antiferromagnetic coupling at spin-defect lines

Abstract

Altermagnetism is a newly identified magnetic phase, distinct from conventional ferromagnetism and antiferromagnetism. It exhibits no net magnetization while breaking time-reversal symmetry. Although its momentum-space signatures are established, direct real-space visualization of its defining rotational-symmetry breaking remains missing. Here, using scanning tunnelling microscopy, we provide atomic-scale real-space evidence for altermagnetism in CsV2Se2O. Utilizing intrinsic spin defects as probes, we directly visualize the hallmark symmetry breaking through unidirectional electronic patterns and elliptical charging rings, both tied to the alternating spin texture. Moreover, adjacent spin-defect lines exhibit opposite spins and long-range antiferromagnetic coupling, hinting at a novel spin order. Our work moves the field from momentum-space probes to direct real-space visualization, opening a path to explore how this unconventional magnetic order couples to other quantum states.