Exotic superconducting properties in the electron-hole-compensated heavy-fermion "semimetal" URuSi

Kasahara, Yuichi*; Iwasawa, Takuya*; Shishido, Hiroaki*; Shibauchi, Takasada*; Behnia, K.*; Haga, Yoshinori   ; Matsuda, Tatsuma; Onuki, Yoshichika; Sigrist, M.*; Matsuda, Yuji*

We show that the charge and thermal transport measurements on ultraclean crystals of URuSi reveal a number of unprecedented superconducting properties. The uniqueness is best highlighted by the peculiar field dependence of thermal conductivity including the first order transition at with a reduction of entropy flow. This is a consequence of multi-band superconductivity with compensated electronic structure in the hidden order state of this system. We provide strong evidence for a new type of unconventional superconductivity with two distinct gaps having different nodal topology.