Pressure-induced phase transitions in multiferroic RbFe(MoO4)2—Raman scattering study

High pressure Raman scattering experiments were performed on RbFe(MoO4)2. These experiments revealed that two phase transitions take place in RbFe(MoO4)2 at very low pressures, i.e. between ambient pressure and 0.2 GPa and between 0.4 and 0.7 GPa. Raman results showed that at the first phase transition the room temperature P3̄m1 phase transforms into the P3̄ phase, which is also observed at ambient pressure below 190 K. The second pressure-induced phase transition occurs into a low symmetry phase of unknown symmetry. The performed lattice dynamics calculations for the P3̄m1 phase and ab initio calculation of the structural changes under hydrostatic pressure helped us to get better insights into the mechanism of the observed phase transitions.