# Magnetoelastic couplings in the deformed Kagom\'{e} quantum spin lattice of volborthite

## TL;DR

This study investigates magnetoelastic couplings in volborthite's deformed Kagomé lattice, revealing negative magnetostriction linked to local spin correlations and supporting a coupled-trimer model through experimental and computational evidence.

## Contribution

It introduces a detailed analysis of magnetoelastic effects in volborthite, connecting lattice changes to spin correlations and validating a coupled-trimer model with combined experimental and theoretical methods.

## Key findings

- Negative longitudinal magnetostriction observed along the b axis
- Magnetostriction depends on magnetization as ΔL/L ∝ M^{1.3}
- Supported by DFT+U calculations and finite-size spin correlation analysis

## Abstract

Microscopic spin interactions on a deformed Kagom\'{e} lattice of volborthite are investigated through magnetoelastic couplings. A negative longitudinal magnetostriction $\Delta L<0$ in the $b$ axis is observed, which depends on the magnetization $M$ with a peculiar relation of $\Delta L/L \propto M^{1.3}$. Based on the exchange striction model, it is argued that the negative magnetostriction originates from a pantograph-like lattice change of the Cu-O-Cu chain in the $b$ axis, and that the peculiar dependence arises from the local spin correlation. This idea is supported by DFT+$U$ calculations simulating the lattice change and a finite-size calculation of the spin correlation, indicating that the recently proposed coupled-trimer model is a plausible one.