Structural, magnetic and vibrational properties of multiferroic GaFeO3 at high pressure

The crystal, magnetic structure and vibrational spectra of multiferroic GaFeO3 have been studied by means of neutron, X-ray powder diffraction and Raman spectroscopy at pressures up to 6.2 and 42 GPa, respectively. A presence of Fe/Ga antisite disorder leads to a formation of the ferrimagnetic ground state with the Néel temperature TN = 292 K at ambient pressure. Upon compression, the magnetic ground state symmetry remains the same and the Néel temperature increases with a pressure coefficient (1/TN)(dTN/dP) = 0.011(1) GPa−1. Application of high pressure above 21 GPa leads to a gradual structural phase transition from the polar orthorhombic Pc21n phase to nonpolar orthorhombic Pbnm phase. It is accompanied by anomalies in the pressure behaviour of several Raman modes. Pressure dependencies of lattice parameters and Raman modes frequencies in the observed structural phases were obtained.