Frustration driven structural distortion in VOMoO4

TL;DR

This paper investigates the frustrated magnetic properties and structural distortion in VOMoO4, revealing a temperature-driven lattice distortion linked to magnetic frustration and valence fluctuations, with implications for understanding complex magnetic materials.

Contribution

It presents the first combined experimental and theoretical study of the structural distortion driven by magnetic frustration in VOMoO4.

Findings

VOMoO4 is a frustrated 2D antiferromagnet with competing J1 and J2 interactions.

A structural distortion occurs around 100 K, likely due to frustration.

The distortion affects NMR and EPR spectra, indicating growing distorted domains near Tc=42 K.

Abstract

Nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), magnetization measurements and electronic structure calculations in VOMoO4 are presented. It is found that VOMoO4 is a frustrated two-dimensional antiferromagnet on a square lattice with competing exchange interactions along the side J1 and the diagonal J2 of the square. From magnetization measurements J1+J2 is estimated around 155 K, in satisfactory agreement with the values derived from electronic structure calculations. Around 100 K a structural distortion, possibly driven by the frustration, is evidenced. This distortion induces significant modifications in the NMR and EPR spectra which can be accounted for by valence fluctuations. The analysis of the spectra suggests that the size of the domains where the lattice is distorted progressively grows as the temperature approaches the transition to the magnetic ground state at Tc=42 K.