Superconducting properties of Cu intercalated Bi$_2$Se$_3$ studied by Muon Spin Spectroscopy
We present muon spin rotation measurements on superconducting Cu intercalated Bi$_2$Se$_3$, which was suggested as a realization of a topological superconductor. We observe a clear evidence of the superconducting transition below 4 K, where the width of magnetic field distribution increases as the temperature is decreased. The measured broadening at mK temperatures suggests a large London penetration depth in the $ab$ plane ($λ_{\mathrm{eff}}\sim 1.6$ $\mathrmμ$m). We show that the temperature dependence of this broadening follows the BCS prediction, but could be consistent with several gap symmetries.
cond-mat.supr-con↗