Local symmetry and magnetic anisotropy in multiferroic MnWO4 and antiferromagnetic CoWO4 studied by soft x-ray absorption spectroscopy

TL;DR

This study uses soft x-ray absorption spectroscopy to analyze the local symmetry and magnetic anisotropy in MnWO4 and CoWO4, revealing how orbital moments influence their magnetic orders and multiferroic properties.

Contribution

It provides detailed insights into the ground state wave functions and the role of spin-orbit coupling in the magnetic behavior of MnWO4 and CoWO4, advancing understanding of multiferroic materials.

Findings

Orbital moment in CoWO4 drives collinear antiferromagnetism.

Weak spin-orbit coupling in MnWO4 allows spiral magnetic order.

Polarization dependence helps determine ground state wave functions.

Abstract

Soft x-ray absorption experiments on the transition metal L2,3 edge of multiferroic MnWO4 and antiferromagnetic CoWO4 are presented. The observed linear polarization dependence, analyzed by full-multiplet calculations, is used to determine the ground state wave function of the magnetic Mn2+ and Co2+ ions. The impact of the local structure and the spin-orbit coupling on the orbital moment is discussed in terms of the single-ion anisotropy. It is shown that the orbital moment in CoWO4 is responsible for the collinear antiferromagnetism, while the small size of spin-orbit coupling effects make spiral magnetic order in MnWO4 possible, enabling the material to be multiferroic.