Superconducting double transition and the upper critical field limit of Sr2RuO4 in parallel magnetic fields

• Published in: Journal of the Physical Society of Japan 2002-12, Vol.71 (12), p.2839-2842
• Main Authors: DEGUCHI, Kazuhiko, TANATAR, Makariy A, MAO, Zhiqiang, ISHIGURO, Takehiko, MAENO, Yoshiteru
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Metals, alloys and compounds (a15, 001c15, laves phases, chevrel phases, borocarbides, etc.); Mixed state, critical fields, and surface sheath; Physics; Properties of type I and type II superconductors; Superconducting materials (excluding high-tc compounds); Superconductivity
• ISSN: 0031-9015; 1347-4073
• DOI: 10.1143/JPSJ.71.2839

We studied the specific heat and thermal conductivity of the spin-triplet superconductor Sr2RuO4 at low temperatures and under oriented magnetic fields H. We resolved a double peak structure of the superconducting transition under magnetic field for the first time, which provides thermodynamic evidence for the existence of multiple superconducting phases. We also found a clear limiting of the upper critical field Hc2 for the field direction parallel to the RuO2 plane only within ± 2°. The limiting of Hc2 occurs in the same H-T domain of the second superconducting phase; we suggest that the two phenomena have the same physical origin.