Superconducting Properties of La${}_2$(Cu${}_{1-x}$Ni_x)${}_5$As${}_3$O${}_2$: A $\mu$SR Study

We report the results of muon spin rotation and relaxation ($\mu$SR) measurements on the recently discovered layered Cu-based superconducting material La${}_2($Cu${}_{1-x}$Ni${}_x$)${}_5$As${}_3$O${}_2$ ($x=$ 0.40, 0.45). Transverse-field $\mu$SR experiments on both samples show that the temperature dependence of superfluid density is best described by a two-band model. The absolute values of zero-temperature magnetic penetration depth ${\lambda }_{\mathrm{a}\mathrm{b}}(0)$ were found to be 427(1.7) nm and 422(1.5) nm for $x=$ 0.40 and 0.45, respectively. Both compounds are located between the unconventional and the standard BCS superconductors in the Uemura plot. No evidence of time-reversal symmetry (TRS) breaking in the superconducting state is suggested by zero-field $\mu$SR measurements.