Phase transitions and p–T phase diagram of the multiferroic TbFe3(BO3)4 crystal

Abstract The structural phase transitions in multiferroic TbFe 3 (BO 3 ) 4 with change hydrostatic pressures and temperatures have been studied by Raman spectroscopy and calculation within density functional theory. Lattice dynamics calculations in the TbFe 3 (BO 3 ) 4 crystal in the phase under various values of applied hydrostatic pressure (from 0 up to 5 GPa with 1 GPa step) were performed. The calculation performed in this work in a TbFe 3 (BO 3 ) 4 crystal showed that the applied pressure can increase the phase transition temperature. Raman spectra of the TbFe 3 (BO 3 ) 4 crystal have been investigated at simultaneously high temperature and high pressure (up to 5.14 GPa and 465 K). The appearance of a soft mode was observed with decreasing temperature at normal pressure. The manifestations of the interaction of the structural and magnetic order parameters in the range from 13 to 50 K were observed at normal pressure. With increasing pressure and a fixed temperature, recovery of the soft modes is also observed. The experimental p–T phase diagram of TbFe 3 (BO 3 ) 4 was established. An increase in pressure leads to an increase in the temperature of transition.