Thermal expansion of RFeAsO (R=La,Ce,Pr,Sm,Gd)

TL;DR

This study measures the thermal expansion of RFeAsO compounds, revealing magneto-elastic coupling, structural transitions, and rare earth magnetic ordering effects through anomalies in the thermal expansion coefficient.

Contribution

It provides new experimental data on thermal expansion and magneto-elastic effects in RFeAsO compounds with various rare earth elements.

Findings

Anomalies at magnetic ordering transitions indicate strong magneto-elastic coupling.

Structural transitions cause large anomalies in thermal expansion coefficient.

Rare earth magnetic ordering produces significant anomalies at low temperatures.

Abstract

We present measurements of the thermal expansion coefficient $\alpha$ of polycrystalline RFeAsO (R = La,Ce,Pr,Sm,Gd). Anomalies at the magnetic ordering transitions indicate a significant magneto-elastic coupling and a negative pressure dependence of $T_{\rm N}$ . The structural transitions are associated by large anomalies in $\alpha$. Rare earth magnetic ordering in CeFeAsO, PrFeAsO, and SmFeAsO yields large positive anomalies at low temperatures.