Bulk properties of the Kondo-like system UCoGe

Robert Troc (1) , Ryszard Wawryk (2) , Wojciech Miiller (2) , Halina Misiorek (2) , Malgorzata Samsel-Czekala (2)

1 Department of Magnetic Investigation
2 Institute of Low Temperature and Structure Research [Polish Academy of Sciences]

We report on extensive experimental investigation of a single crystal of the orthorhombic uranium compound UCoGe. Bulk measurements being done on as grown and annealed single crystals as magnetization, magnetic susceptibility, electrical resistivity, magnetoresistivity, thermopower, thermal conductivity, and heat capacity data do not reproduce the previously reported coexistence of ferromagnetism with superconductivity. The latter phenomenon was only observed for the annealed sample with T_SC = 0.65 K. Quite new observations are a crossover at around 13 K visible in thermal and transport measurements as well as the coherent state around 50 K signalized by a wide knee in ρ(T). Above this temperature UCoGe exhibits a single-ion Kondo-like effect. The magnetoresistivity of the annealed single crystal is increasing negatively down to 4.2 K, reaching as a large value as about -27% at a field of 8 T. The latter may be interpreted in terms of fairly strong magnetic fluctuations existing in UCoGe at low temperatures. PACS numbers: 74.25.-q, 74.25.Ha, 75.20.Hr, 75.47.-m

Mots clés: Physical Sciences

Robert Troc, Ryszard Wawryk, Wojciech Miiller, Halina Misiorek, Malgorzata Samsel-Czekala. Bulk properties of the Kondo-like system UCoGe. Philosophical Magazine, 2010, 90 (16), pp.2249-2271. ⟨10.1080/14786431003630900⟩. ⟨hal-00592297⟩