Antiferromagnetic spin canting and Magnetoelectric Multipoles in h-YMnO$_3$

TL;DR

This study investigates the magnetic structure of hexagonal YMnO₃, revealing out-of-plane spin canting and magnetoelectric multipoles through resonant X-ray diffraction and ab initio calculations, highlighting complex magnetic interactions in multiferroic materials.

Contribution

It provides the first observation of out-of-plane spin canting and links it to magnetoelectric multipoles using combined experimental and theoretical approaches.

Findings

Detection of out-of-plane Mn³⁺ magnetic moment canting.

Observation of symmetry-forbidden magnetic Bragg reflection.

Spectral differences explained by interference with atomic multipoles.

Abstract

Hexagonal YMnO$_{3}$ is a prototype antiferromagnet which exhibits multiferroic behavior with the ferroelectric and magnetic transitions occurring at different temperatures. We observe an out-of-plane canting of the Mn$^{3+}$ magnetic moments using resonant X-ray diffraction (RXD) in a single crystal of this material. These canted moments result in the symmetry-forbidden (0,0,1) magnetic Bragg reflection, which is observed at the Mn $L_{2,3}$ absorption edges. We also observe an unexpected difference in the RXD spectral shapes at different temperatures. Using ab initio calculations, we explore the possibility that this behavior arises due to the interference between scattering from the canted magnetic moments and parity-odd atomic multipoles on the Mn$^{3+}$ ions.