4 research outputs found
Hidden Quantum Critical Point in a Ferromagnetic Superconductor
We consider a coexistence phase of both Ferromagnetism and superconductivity
and solve the self-consistent mean-field equations at zero temperature. The
superconducting gap is shown to vanish at the Stoner point whereas the
magnetization doesn't. This indicates that the para-Ferro quantum critical
point becomes a hidden critical point. The effective mass in such a phase gets
enhanced whereas the spin wave stiffness is reduced as compared to the pure FM
phase. The spin wave stiffness remains finite even at the para-Ferro quantum
critical point.Comment: 4 pages, Phys. Rev. B (Rapid) accepte
Dilatometry study of the ferromagnetic order in single-crystalline URhGe
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.Comment: 5 page