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Possible Anisotropic Order Parameter in Pyrochlore Superconductor KOs$_2$O$_6$ Probed by Muon Spin Rotation

A. Koda·W. Higemoto·K. Ohishi·S. R. Saha·R. Kadono·S. Yonezawa·Y. Muraoka·Z. Hiroi
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Abstract

Magnetic penetration depth ($λ$) 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 $λ^{-2}$, exhibits a considerable deviation from that expected for the empirical two-fluid model ($\propto T^4$), rather obeying a $T^2$-tendency. Furthermore, $λ$ 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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A. Koda, W. Higemoto, K. Ohishi, S. R. Saha, R. Kadono, S. Yonezawa, Y. Muraoka, Z. Hiroi. 2005-04-08. Possible Anisotropic Order Parameter in Pyrochlore Superconductor KOs$_2$O$_6$ Probed by Muon Spin Rotation. https://doi.org/10.1143/jpsj.74.1678

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