Experimental evidence of anapolar moments in the antiferromagnetic insulating phase of V2O3 obtained from x-ray resonant Bragg diffraction

TL;DR

This study provides experimental evidence of anapolar moments in the antiferromagnetic insulating phase of V2O3 using resonant x-ray diffraction, revealing magnetoelectric multipoles and advancing understanding of its physical properties.

Contribution

It demonstrates the presence of anapolar moments in V2O3 through resonant x-ray diffraction and models their ordering using magnetic space groups and multipole analysis.

Findings

Evidence of anapolar moments in V2O3

Resonant x-ray diffraction detects magnetoelectric multipoles

Model successfully explains forbidden Bragg reflection intensities

Abstract

We have investigated the antiferromagnetic insulating phase of the Mott-Hubbard insulator V$_2$O$_3$ by resonant x-ray Bragg diffraction at the vanadium K-edge. Combining the information obtained from azimuthal angle scans, linear incoming polarization scans and by fitting collected data to the scattering amplitude derived from the established chemical I2/a and magnetic space groups we provide evidence of the ordering motif of anapolar moments (which results from parity violation coupling to an electromagnetic field). Experimental data (azimuthal dependence and polarization analysis) collected at space-group forbidden Bragg reflections are successfully accounted within our model in terms of vanadium magnetoelectric multipoles. We demonstrate that resonant x-ray diffraction intensities in all space-group forbidden Bragg reflections of the kind $(hkl)_m$ with odd $h$ are produced by an E1-E2 event. The determined tensorial parameters offer a test for ab-initio calculations in this material, that can lead to a deeper and more quantitative understanding of the physical properties of V$_2$O$_3$.