  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.
