Spin fluctuations in Gd₃Rh induced by f–d exchange: the influence on the T-linear specific heat

The results of specific heat, magnetization and magnetic susceptibility measurements for the antiferromagnetic (AF) compound Gd₃Rh are presented. Below its Néel temperature T_N = 112 K, this compound exhibits a field-induced phase transition from the AF to the ferromagnetic state in a relatively small magnetic field (∼0.4 T). Specific heat measurements revealed a giant enhancement of the coefficient of the T-linear specific heat in Gd₃Rh (γ = 118 mJ mol⁻¹ K⁻²) in comparison with that observed for the isostructural nonmagnetic partner Y₃Rh (γ = 11 mJ mol⁻¹ K⁻²). An anomalous behaviour of the heat capacity as well as a set of peculiarities of magnetic properties in Gd₃Rh are associated with the existence of spin fluctuations induced by f–d exchange interaction in the d-electron subsystem that arises from features of the crystal and electronic structure of the R₃M-type compounds.