S. Osaki

Multiple superconducting phases in new heavy fermion superconductor PrOs4Sb12

The superconducting gap structure of recently discovered heavy fermion superconductor PrOs4Sb12 was investigated by using thermal transport measurements in magnetic field rotated relative to the crystal axes. We demonstrate that a novel change in the symmetry of the superconducting gap function occurs deep inside the superconducting state, giving a clear indication of the presence of two distinct superconducting phases with twofold and fourfold symmetries. We infer that the gap functions in both phases have a point node singularity, in contrast to the familiar line node singularity observed in almost all unconventional superconductors.

Fermi surface of the heavy-fermion superconductorPrOs4Sb12

We have investigated the de Haas-van Alphen effect in the Pr-based heavy-fermion superconductor PrOs 4 Sb 1 2 . The topology of Fermi surface is close to the reference compound LaOs 4 Sb 1 2 and well explained by the band-structure calculation based on the FLAPW (full potential linearized augmented-plane-wave)-LDA (local-density approximation) +U method, where the 4f electrons are localized. We have confirmed a highly enhanced cyclotron effective mass (2.4-7.6)m 0 , which is apparently large compared to the usual Pr-based compounds.

Transport properties in CeOs4Sb12 : Possibility of the ground state being semiconducting

We have measured both magnetoresistance and Hall effect in CeOs

Transport properties of the heavy-fermion superconductorPrOs4Sb12

_4

Transport and thermal properties of Ce- and Pr-filled skutterudites

Sb

Exotic behaviours in the Pr-based filled skutterudites

_{12}

High field magnetoresistance in heavy fermion superconductor PrOs4Sb12

to clarify the large resistivity state ascribed to the Kondo insulating one and the origin of the phase transition near 0.9 K reported in the specific heat measurement. We found unusual temperature (

Fermi surface of the heavy-fermion superconductor PrOs4Sb12

T

Sb-NQR study of the “Kondo semiconductor” CeOs4Sb12

) dependence both in the electrical resistivity

High field magnetoresistance in CeOs4Sb12

\rho\sim T^{-1/2}