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Field-Induced Quasiparticle Excitation in Ca(Al$_{0.5}$Si$_{0.5}$)$_2$: Evidence for unconventional Superconductivity

S. Kuroiwa·H Takagiwa·M. Yamazawa·J. Akimitsu·K. Ohishi·A. Koda·W. Higemoto·R. Kadono
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Abstract

The temperature ($T$) and magnetic field ($H$) dependence of the magnetic penetration depth, $\lambda(T,H)$, in Ca(Al$_{0.5}$Si$_{0.5}$)$_2$ exhibits significant deviation from that expected for conventional BCS superconductors. In particular, it is inferred from a field dependence of $\lambda(H)$ ($\propto H$) at 2.0 K that the quasiparticle excitation is strongly enhanced by the Doppler shift. This suggests that the superconducting order parameter in Ca(Al$_{0.5}$Si$_{0.5}$)$_2$ is characterized by a small energy scale $\Delta_S/k_B\le 2$ K originating either from anisotropy or multi-gap structure.

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S. Kuroiwa, H Takagiwa, M. Yamazawa, J. Akimitsu, K. Ohishi, A. Koda, W. Higemoto, R. Kadono. 2004-02-18. Field-Induced Quasiparticle Excitation in Ca(Al$_{0.5}$Si$_{0.5}$)$_2$: Evidence for unconventional Superconductivity. https://doi.org/10.1143/jpsj.73.2631

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