Nodal gap structure of the heavy-fermion superconductor URu2Si2 revealed by field-angle-dependent specific-heat measurements

Shunichiro Kittaka, Yusei Shimizu, Toshiro Sakakibara, Yoshinori Haga, Etsuji Yamamoto, Yoshichika O'Nuki, Yasumasa Tsutsumi, Takuya Nomoto, Hiroaki Ikeda, Kazushige Machida

Research output: Contribution to journalConference articlepeer-review

1 Citation (Scopus)

Abstract

URu2Si2 is a promising candidate for a chiral d-wave superconductor whose gap is composed of a horizontal line node at equator and point nodes at the north and south poles. However, previous measurements of the specific heat and the thermal conductivity did not detect quasiparticle excitations from a horizontal line node in heavy-mass bands. Here, we have provided strong evidence for the presence of a horizontal line node from field-angle-dependent specific-heat measurements by using a high-quality single crystal of URu2Si2. We observed the behavior of the specific heat at low fields which does not depend on inplane field angle φ but shows a shoulder-like anomaly in the polar-angle θ dependence around θ ∼ 45°. This feature is more clearly seen at lower temperatures, suggesting the detection of low-energy quasiparticle excitations reflecting the gap structure. From theoretical analyses based on microscopic calculations, we have demonstrated that this anomaly can be explained by the existence of a horizontal line node at kz = 0. Thus, the gap structure of URu2Si2 matches well with the Eg chiral kz(kx + iky) symmetry.

Original languageEnglish
Article number052001
JournalJournal of Physics: Conference Series
Volume807
Issue number5
DOIs
Publication statusPublished - 2017 Apr 6
Event18th International Conference on Strongly Correlated Electron Systems, SCES 2016 - Hangzhou, China
Duration: 2016 May 92016 May 13

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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