Evidence for Chiral d-Wave Superconductivity in URu2Si2 from the Field-Angle Variation of Its Specific Heat

• DOI: 10.7566/jpsj.85.033704
• Publication Date: 2016-02-05T01:04:35Z
• Authors: Shunichiro Kittaka; Yusei Shimizu; Toshiro Sakakibara; Yoshinori Haga; Etsuji Yamamoto; Yoshichika Ōnuki; Yasumasa Tsutsumi; Takuya Nomoto; Hiroaki Ikeda; Kazushige Machida
• Keywords: Heavy fermion superconductor

Low-energy quasiparticle (QP) excitations in the heavy-fermion superconductor URu$_2$Si$_2$ were investigated by specific-heat $C(T, H, ϕ, θ)$ measurements of a high-quality single crystal. The occurrence QP due to Doppler-shift effect was detected regardless field direction $C(H)$ present clean sample, which is sharp contrast previous report. Furthermore, polar-angle-dependent $C(θ)$ measured under rotating magnetic within ac plane exhibits shoulder-like anomaly at $θ\sim 45$ deg and dip $θ= 90$ ($H \parallel a$) moderate-field region. These features are supported theoretical analyses based on microscopic calculations assuming gap symmetry $k_z(k_x+ik_y)$, whose structure characterized combination horizontal line node equator point nodes poles. results have settled controversy over authenticated its chiral $d$-wave superconductivity.