Magnetic response in the superconducting state of 1H-Ca(Al0.5Si0.5)2 studied by μSR

Magnetic field dependence of the effective penetration depth (λ) determined by μSR is reported for 1H-Ca(Al0.5Si0.5)2, a structurally new phase of Ca(Al0.5Si0.5)2. The new phase has an AlB2-type crystal structure with P3 symmetry which, in contrast to earlier reports, does not exhibit superlattice structure along the c-axis. The bulk susceptibility measurement indicates that the upper critical field is much lower than that in superstructured ones for both c- and a-axis directions. A weak anisotropy in the superconducting order parameter is suggested from the increase of λ with increasing external field.