Phenomenological model of elastic distortions near the spin-Peierls transition in $CuGeO_3$

TL;DR

This paper presents a phenomenological Landau-type model to explain elastic distortions and anomalies near the spin-Peierls transition in CuGeO_3, highlighting the roles of copper and oxygen displacements.

Contribution

It introduces a new phenomenological model that accounts for atomic displacements and elastic anomalies near the transition, incorporating linear coupling between copper and oxygen distortions.

Findings

Copper displacements cause elastic anomalies at T_c

Oxygen distortions influence temperature dependence below T_c

The model discusses potential critical behavior near the transition

Abstract

A phenomenological model of the Landau type forms the basis for a study of elastic distortions near the spin-Peierls transition $T_c$ in $CuGeO_3$. The atomic displacements proposed by Hirota {\it et al.} [Phys. Rev. Lett. {\bf 73}, 736 (1994)] are accounted for by the model which includes linear coupling between $Cu$ and $O$ distortions. $Cu$ displacements are seen to be responsible for anomalies in the elastic properties {\it at} $T_c$, whereas incipient $O$ distortions give rise to temperature dependence below $T_c$. A discussion of possible critical behavior is also made.