Effect of high pressure on the crystal structure, magnetic, and vibrational properties of multiferroic RbFe(MoO4)2

Abstract

The structural, magnetic, and vibrational properties of RbFe(MoO 4)2 have been studied by means of x-ray and neutron powder diffraction, magnetic susceptibility measurements, and Raman spectroscopy at pressures up to 10 GPa. The gradual structural phase transition from the initial trigonal P3̄m1 phase to the monoclinic C2/c phase via the intermediate P3̄ phase was observed at P∼1 GPa. The triangular antiferromagnetic order with a propagation vector q = (1/3, 1/3, qz) in the suppressed trigonal phase remains incommensurate, and the qz value increases from 0.45 to 0.48 in the pressure range 0-2 GPa at T=2 K. The pressure coefficient of the Néel temperature is equal to (1/TN)dT N/dP=0.09GPa-1. No evidence of the formation of the long-range magnetic order in the monoclinic phase was found. The pressure dependencies of the vibrational modes for the trigonal and monoclinic phases were obtained. © 2013 American Physical Society.