Possible Anisotropic Order Parameter in Pyrochlore Superconductor KOs₂O₆ Probed by Muon Spin Rotation

A. Koda, Wataru Higemoto, Kazuki Ohishi, Shanta Saha, R. Kadono, Shigeki Yonezawa, Yuji Muraoka, Zenji Hiroi

Abstract

Magnetic penetration depth ($\lambda$) in a pyrochlore superconductor KOs$_2$O$_6$ was studied by means of muon spin rotation (\msr). The temperature dependence of transverse spin relaxation rate, which is proportional to $\lambda ^{-2}$, exhibits a considerable deviation from that expected for the empirical two-fluid model ($\propto T^4$), rather obeying a $T^2$-tendency. Furthermore, $\lambda$ apparently increases with increasing applied field, suggesting the presence of nonlinear and nonlocal effects. These findings strongly suggest that the superconducting order parameter in KOs$_2$O$_6$ is anisotropic.

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• Journal of the Physical Society of Japan - View
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