Magnetoelastic coupling in CuFeO2

Abstract

Ultrasonic velocity data obtained on CuFeO2 are re-analyzed in the context of a Landau free energy which includes spin-lattice coupling. This comprehensive model simultaneously accounts for the elastic and magnetic properties of CuFeO2 at zero field. Softening of the elastic constants C11, C44, and especially C66, ineluctably indicates that the R3m -C2=m structural transition at TN1 = 13:7 K is primarily pseudoproper ferroelastic. The present analysis also suggests that the elastic anomalies observed at TN2 are dominated by magnetoelastic coupling and strengthens the conclusion that the unusual properties of CuFeO2 are a consequence of the interplay between its magnetism and elastic deformations. © 2009 IOP Publishing Ltd.