Strong spin-lattice coupling in multiferroic HoMnO$_{3}$: Thermal expansion anomalies and pressure effect

TL;DR

This study demonstrates strong spin-lattice coupling in multiferroic HoMnO₃ through thermal expansion anomalies and pressure effects, revealing significant magnetoelastic interactions and phase transition characteristics.

Contribution

It provides experimental evidence of strong spin-lattice coupling in HoMnO₃, highlighting thermal expansion anomalies and first-order phase transition behavior.

Findings

Anomalies in thermal expansivities at T_N and T_SR

Negative c-axis expansivity below room temperature

Discontinuities indicating a first order phase transition

Abstract

Evidence for a strong spin-lattice coupling in multiferroic HoMnO_3 is derived from thermal expansion measurements along a- and c-axis. The magnetoelastic effect results in sizable anomalies of the thermal expansivities at the antiferromagnetic (T_N) and the spin rotation (T_{SR}) transition temperatures as well as in a negative c-axis expansivity below room temperature. The coupling between magnetic orders and dielectric properties below T_N is explained by the lattice strain induced by the magnetoelastic effect. At T_{SR} various physical quantities show discontinuities that are thermodynamically consistent with a first order phase transition.