LONDON PENETRATION DEPTH OF CaAlSi SUPERCONDUCTORS BY SEMI-CLASSICAL APPROACH

The temperature dependence of the London penetration depth in-plane (ab plane) and out-plane (c axis) of single band anisotropic S-wave superconductors was investigated by semi-classical theory in 3D spherical Fermi surface. The ellipse spherical and pancake spherical gap model were used as anisotropic model for energy gap. The London penetration depth was derived by analytical and numerical approach and applied to CaAlSi-I and CaAlSiII superconductors. We found that our model can fit well with experimental data of CaAlSiI and CaAlSiII at low temperature scenery. CaAlSi-I showed anisotropic and isotropic properties in ab plane and c axis respectively and CaAlSi-II showed anisotropic properties both in-plane and out-plane.