Novel Features in the Flux-Flow Resistivity of the Heavy Fermion Superconductor PrOs₄Sb₁₂

Abstract

We have investigated the electrical resistivity of the heavy fermion\nsuperconductor PrOs$_{4}$Sb$_{12}$ in the mixed state. We found unusual double\nminima in the flux-flow resistivity as a function of magnetic field below the\nupper critical field for the first time, indicating double peaks in the pinning\nforce density ($F_{\\rm P}$). Estimated $F_{\\rm P}$ at the peak exhibits\napparent dependence on applied field direction; composed of two-fold and\nfour-fold symmetries mimicking the reported angular dependence of thermal\nconductivity ($\\kappa$). The result is discussed in correlation with the double\nstep superconducting (SC) transition in the specific heat and the multiple\nSC-phases inferred from the angular dependence of $\\kappa$.\n