Fluctuation effects on the physical properties of Cd2Re2O7 near 200 K

Experimental investigation of the resistivity rho, susceptibility chi, specific heat C-p and Hall coefficient R-H of the pyrochlore Cd2Re2O7 reveals the presence of a continuous phase transition of uncertain origin with critical temperature T* = 200 K. Electron and x-ray diffraction measurements indicate that a commensurate structural transformation accompanies the changes in the electronic properties, implying that lattice as well as electronic degrees of freedom are involved in the transition. Remarkable scaling relationships between rho, chi and C-p are observed, indicating that fluctuations are crucial in the transition regime. Both spin and ionic density fluctuation scenarios are considered.