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

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.

4 pages, 4 figures, submitted to J. Phys. Soc. Jpn

References in corpus (4)

• Phenomenological two-gap model for the specific heat of MgB_2
• Gap Function with Point Nodes in Borocarbide Superconductor YNi_2B_2C
• Quasiparticle Excitations outside the Vortex Cores in MgB${}_2$ Probed by Muon Spin Rotation
• Nonlocal Effects and Shrinkage of the Vortex Core Radius in YNi2B2C Probed by muSR

Cited by in corpus (4)

• Magnetic Penetration Depth in Unconventional Superconductors
• Electrons and phonons in the ternary alloy CaAl${}_{2-x}$Si${}_x$} as a function of composition
• Anisotropic s-wave superconductivity in single crystals CaAlSi from penetration depth measurements
• Sub-THz electrodynamics of the graphene-like superconductor CaAlSi