Correlation between Superconducting Carrier Density and Transition Temperature in NbB${}_{2+x}$

H. Takagiwa, S. Kuroiwa, M. Yamazawa +5

We report on the magnetic penetration depth, lambda, in a type II superconductor NbB_{2+x} determined by muon spin rotation method. We show in the sample with x=0.1 that lambda at…