Evidence of nodes in the order parameter of the superconducting doped topological insulator Nb${}_x$Bi${}_2$Se${}_3$ via penetration depth measurements

M. P. Smylie, H. Claus, U. Welp +4

The low-temperature variation of the London penetration depth $\lambda (T)$ in the candidate topological superconductor Nb${}_x$Bi${}_2$Se${}_3$ (x = 0.25) is reported for several crystals. The…