Giant X-ray circular dichroism in a time-reversal invariant altermagnet

Abstract

X-ray circular dichroism, arising from the contrast in X-ray absorption between opposite photon helicities, serves as a spectroscopic tool to measure the magnetization of ferromagnetic materials and identify the handedness of chiral crystals. Antiferromagnets with crystallographic chirality typically lack X-ray magnetic circular dichroism because of time-reversal symmetry, yet exhibit weak X-ray natural circular dichroism. Here, we report the observation of giant natural circular dichroism in the Ni $L_3$-edge X-ray absorption of Ni${}_3$TeO${}_6$, a polar and chiral antiferromagnet with effective time-reversal symmetry. To unravel this intriguing phenomenon, we propose a phenomenological model that classifies the movement of photons in a chiral crystal within the same symmetry class as that of a magnetic field. The coupling of X-ray polarization with the induced magnetization yields giant X-ray natural circular dichroism, revealing the altermagnetism of Ni${}_3$TeO${}_6$. Our findings provide evidence for the interplay between magnetism and crystal chirality in natural optical activity. Additionally, we establish the first example of a new class of magnetic materials exhibiting circular dichroism with time-reversal symmetry.

Accepted by Advanced Materials (2024.2.16) Revised title: Giant X-ray circular dichroism in a time-reversal invariant altermagnet Revised drafts: Main 14 pages, 4 figures, and SI 20 pages, 8 figures

References in corpus (5)

• Altermagnetism with Non-collinear Spins
• Presence of x-ray magnetic circular dichroism effect for zero-magnetization state in antiferromagnetism
• Observation of spontaneous x-ray magnetic circular dichroism in a chiral antiferromagnet
• Diagonal and off-diagonal thermal conduction with resonant phonon scattering in $N{i}_{3}Te{O}_6$
• Determination of spin chirality using x-ray magnetic circular dichroism

Cited by in corpus (3)

• Systematic Mapping of Altermagnetic Magnons by Resonant Inelastic X-Ray Circular Dichroism
• X-ray magnetic circular dichroism originating from the $T_z$ term in collinear altermagnets under trigonal crystal field
• Single-ion anisotropy driven chiral magnetic order in a spin-1 antiferromagnetic chain