Novel features in the flux-flow resistivity of the heavy fermion superconductor PrOs${}_4$Sb${}_{12}$

Abstract

We have investigated the electrical resistivity of the heavy fermion superconductor PrOs${}_4$Sb${}_{12}$ in the mixed state. We found unusual double minima in the flux-flow resistivity as a function of magnetic field below the upper critical field for the first time, indicating double peaks in the pinning force density ($F_{\mathrm{P}}$). Estimated $F_{\mathrm{P}}$ at the peak exhibits apparent dependence on applied field direction; composed of two-fold and four-fold symmetries mimicking the reported angular dependence of thermal conductivity ($\hat{I}º$). The result is discussed in correlation with the double step superconducting (SC) transition in the specific heat and the multiple SC-phases inferred from the angular dependence of $\hat{I}º$.

5 pages, 7 figures, to appear in J. Phys. Soc. Jpn. Vol. 74, No. 6 or 7