Magnetostructural coupling in RFeO(3) (R = Nd, Tb, Eu and Gd)

We investigate the interplay of magnetization and lattice vibrations in rare-earth orthoferrites RFeO(3), with a specific focus on non-symmetry-breaking anomalies. To do so, we study the magnetization, magnon excitations and lattice dynamics as a function of temperature in NdFeO(3), TbFeO(3), EuFeO(3) and GdFeO(3). The magnetization shows distinct temperature anomalous behavior for all investigated rare-earth orthoferrites, even in the compounds with no phase transitions occurring at those temperatures. Through spin–phonon coupling, these magnetic changes are mirrored by the FeO(6) rotation mode for all the studied RFeO(3), revealing a common magnetostructural effect associated with the octahedra rotations. The R(3+) oscillation modes evidence a Fe(3+)/R(3+) spins cross-talk for the NdFeO(3) and TbFeO(3) cases. Our work sheds light into the common magnetostructural coupling in rare-earth orthoferrites, and the important role of magnetic anisotropy and spin–orbit coupling strength of the R–Fe interactions on the spin-reorientation transition at high temperatures.