Exotic superconducting state embedded in the hidden order state of URuSi

Matsuda, Yuji*; Okazaki, Ryuji*; Kasahara, Yuichi*; Shishido, Hiroaki*; Shibauchi, Takasada*; Haga, Yoshinori   ; Matsuda, Tatsuma; Onuki, Yoshichika

We report charge and thermal transport measurements on ultra clean single crystals of the superconductor with the hidden-order state URuSi. The results provide strong evidence for a new type of unconventional superconductivity with two distinct gaps having different nodal topology. We propose a gap function with chiral -wave form. We also demonstrate that a distinct flux line lattice melting transition with outstanding characters occurs well below the upper critical fields even at sub-Kelvin temperature.