Spin and orbital excitations in rare-earth vanadates

Perovskite rare-earth vanadates (RVO₃) exhibit a combination of V-orbital, V-spin, and R-spin moments. These moments order at various temperatures depending on their strength, and geometry. The V-orbital moments order at the highest temperature (T_S1∼180 K), followed by the V-spin moments (T_N1∼120 K), and finally, at the lowest temperature (below T_N2∼20 K), the rare-earth spin moments order. Consequently, these are ideal candidates for studying the hierarchy of interactions between the vanadium (3d) orbital and spin orders, and rare-earth (4f) spin orders. The interactions between these orders, when coupled to the lattice, give rise to interesting properties including orbital long-range-ordering and multiferroicity. Inelastic neutron scattering on single crystal samples is one of the most suitable techniques for probing these magnetic interactions, since it directly yields the modes along with their dispersions and energies resolved in the reciprocal space