Identification of spin wave resonances and crystal field levels in simple chromites RCrO3 (R = Pr, Sm, Er) at low temperatures in the THz spectral region

The 5 K AFM and FM excitations in ErCrO3 have a concerted frequency-intensity temperature dependence and a shoulder pointing to the Er3+ smaller ion size also disrupting the two magnetic sublattice approximation. Both resonances reduce to one when the temperature is lowered to 2 K in the Γ1 representation. Our findings have important implications on the complex interplay in the magneto-electrodynamics associated with the Rare-Earth 4f - 3d transition metal spin coupling and the structural A site instabilities in perovskite multiferroics.