Angular dependence of the upper critical field of Sr2RuO4

作者：Kittaka S^*; Nakamura T; Aono Y; Yonezawa S; Ishida K; Maeno Y

来源：Physical Review B, 2009, 80(17): 174514.

DOI：10.1103/PhysRevB.80.174514

• effective mass
• magnetic field effects
• strontium compounds
• superconducting critical field
• superconducting materials

One of the remaining issues concerning the spin-triplet superconductivity of Sr2RuO4 is the strong limit of the in-plane upper critical field H-c2 at low temperatures. In this study, we clarified the dependence of H-c2 on the angle theta between the magnetic field and the ab plane at various temperatures, by precisely and accurately controlling the magnetic field direction. We revealed that, although the temperature dependence of H-c2 for vertical bar theta vertical bar >= 5 degrees is well explained by the orbital pair-breaking effect, H-c2(T) for vertical bar theta vertical bar < 5 degrees is clearly limited at low temperatures. We also revealed that the H-c2 limit for vertical bar theta vertical bar < 5 degrees is present not only at low temperatures but also at temperatures close to T-c. These features may provide additional hints for clarifying the origin of the H-c2 limit. Interestingly, if the anisotropic ratio in Sr2RuO4 is assumed to depend on temperature, the observed angular dependence of H-c2 is reproduced better at lower temperature with an effective-mass model for an anisotropic three-dimensional superconductor. We discuss the observed behavior of H-c2 based on existing theories.

• 出版日期2009-11