Scopul nostru este sprijinirea şi promovarea cercetării ştiinţifice şi facilitarea comunicării între cercetătorii români din întreaga lume.
Autori: C R Rotundu, P Kumar, and B Andraka
Editorial: Physical Review B, 73, p.014515, 2006.
We report the low-temperature susceptibility and specific heat for single crystals of Pr1−xLaxOs4Sb12 (0⩽x⩽1). The ionic properties of the material, characterized by the energy spectrum of crystalline electric field (CEF) levels of Pr, are unchanged by La doping. The average Tc is only weakly affected by La substitution and varies approximately linearly between the end compounds. The discontinuity in the specific heat divided by temperature C∕T at Tc is drastically reduced from about 800 mJ∕K2 mol for x=0 to the value of LaOs4Sb12 near x=0.3. This behavior of a superconducting transition implies a collective origin of the heavy-fermion state in PrOs4Sb12. We suggest that fluctuations of the anti-ferro-quadrupolar order parameter are responsible for this heavy-fermion state
Cuvinte cheie: Superconductivity; Strongly Correlated Electrons