Uncommonly High Upper Critical Field in the Superconducting KOs$_2$O$_6$ Pyrochlore

T. Shibauchi; L. Krusin-Elbaum; Y. Kasahara; Y. Shimono; Y. Matsuda; R. D. McDonald; C. H. Mielke; S. Yonezawa; Z. Hiroi; M. Arai; T. Kita; G. Blatter; M. Sigrist

doi:10.1103/PhysRevB.74.220506

paper

Uncommonly High Upper Critical Field in the Superconducting KOs $_{2}$ O $_{6}$ Pyrochlore

arXiv:cond-mat/0603309 · doi:10.1103/PhysRevB.74.220506

Abstract

The entire temperature dependence of the upper critical field $H_{c2}$ in the $β$ -pyrochlore KOs $_{2}$ O $_{6}$ is obtained from high-field resistivity and magnetic measurements. Both techniques identically give $H_{c2} (T ≃ 0 K)$ not only surprisingly high ( $\sim 33$ T), but also the approach to it unusually temperature-\emph{linear} all the way below $T_{c}$ (= 9.6 K). We show that, while $H_{c2} (0)$ exceeds a simple spin-singlet paramagnetic limit $H_{P}$ , it is well below an $H_{P}$ enhanced due to the missing spatial inversion symmetry reported recently in KOs $_{2}$ O $_{6}$ , ensuring that the pair-breaking here is executed by orbital degrees. {\it Ab initio} calculations of orbital $H_{c2}$ show that the unusual temperature dependence is reproduced if dominant s-wave superconductivity resides on the smaller closed Fermi surfaces.

5 pages, 3 figures. Version accepted for publication as a Rapid Communication in Phys. Rev. B

Uncommonly High Upper Critical Field in the Superconducting KOs $_{2}$ O $_{6}$ Pyrochlore

Abstract

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Uncommonly High Upper Critical Field in the Superconducting KOs2​O6​ Pyrochlore

Abstract

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Uncommonly High Upper Critical Field in the Superconducting KOs $_{2}$ O $_{6}$ Pyrochlore