Violation of the ambegraokar-baratoff relation in the c-axis transport in Bi-2212 high quality stacks

摘要

We studied the c-axis transport in the high quality Bi-2212 stacked junctions fabricated by the double-sided focused ion beam (FIB) processing of the sinlge crystal whiskers. We found the value of the critical current to be considerably (by factor 30) below the value given by the Ambegraokar-Baratoff (AB) relation in the BCS model at low temperaturs. The results are discussed as a possibility of the d-wave partially coherent interlayer tunneling.