Two-channel Kondo effects in Al/AlOx/Sc planar tunnel junctions

Abstract

We have measured the differential conductances G(V, T) in several Al/AlOx/Sc planar tunnel junctions between 2 and 35 K. As the temperature decreases to similar to 16 K, the zero-bias conductance G(0, T) crosses over from a standard -ln T dependence to a novel -root T dependence. Correspondingly, the finite bias conductance G(V, T) reveals a two-channel Kondo scaling behavior between similar to 4 and 16 K. The observed two-channel Kondo physics is ascribed to originating from a few localized spin-1/2 Sc atoms situated slightly inside the AlOx/Sc interface.