Dilatometry study of the ferromagnetic order in single-crystalline URhGe -: art. no. 144407

Thermal expansion measurements have been carried out on single-crystalline URhGe in the temperature range from 2 to 200 K. At the ferromagnetic transition (Curie temperature T-C=9.7 K), the coefficients of linear thermal expansion along the three principal orthorhombic axes all exhibit pronounced positive peaks. This implies that the uniaxial pressure dependencies of the Curie temperature, determined by the Ehrenfest relation, are all positive. Consequently, the calculated hydrostatic pressure dependence dT(C)/dp is positive and amounts to 0.12 K/kbar. In addition, the effective Gruneisen parameter was determined. The low-temperature electronic Gruneisen parameter Gamma(sf) = 14 indicates an enhanced volume dependence of the ferromagnetic spin fluctuations at low temperatures. Moreover, the volume dependencies of the energy scales for ferromagnetic order and ferromagnetic spin fluctuations were found to be identical.