Superconducting properties of La2(Cu1−xNix)5As…

We report the results of muon spin rotation and relaxation $(\ensuremath{\mu}\mathrm{SR})$ measurements on the recently discovered layered Cu-based superconducting material ${\mathrm{La}}_{2}{({\mathrm{Cu}}_{1\ensuremath{-}x}{\mathrm{Ni}}_{x})}_{5}{\mathrm{As}}_{3}{\mathrm{O}}_{2}$ ($x=0.40$ and 0.45). Transverse-field $\ensuremath{\mu}\mathrm{SR}$ 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 ${\ensuremath{\lambda}}_{\mathrm{ab}}(0)$ were found to be 427(1.7) 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 breaking in the superconducting state is suggested by zero-field $\ensuremath{\mu}\mathrm{SR}$ measurements.