Temperature and pressure manipulation of magnetic ordering and phonon dynamics with phase transition in multiferroic GdFeO3: Evidence from Raman scattering

We systematically investigate the detailed dynamics of the phonon and local structure of rare-earth orthoferrites GdFeO3 single crystal with temperature and pressure induced structural/magnetic phase transition by Raman spectroscopy. Phonon evolution related to the motion of octahedra reveals paramagnetic to antiferromagnetic ordering transition of Fe3+ ions at Néel temperature TN,Fe. By quantifying the polarized Raman spectra, especially the cross-polarized geometry, the lattice dynamics and distortion with local structure rearrangement during ferromagnetic transition has been also discovered. Particularly, we claim that the depolarization ratio could be quantified and used to precisely determine ferromagnetic phase transition of GdFeO3 and symmetry evolution simultaneously. Additionally, pressure dependence (up to 25.03 GPa) of collective phonon behavior indicates that antiphase tilt in FeO6 octahedra is more susceptible to the stress field than the in-phase one. The FeO6 octahedra presents better compressible than GdO12 dodecahedra in the GdFeO3 lattice with respect to pressure. This work has discovered the physical mechanism underlying variation of local structural symmetry, octahedra tilt, and phonon dynamics in GdFeO3, which can be regarded as the basic view for a series of GdFeO3-type perovskites and more RFeO3 system.