Evidence for triplet superconductivity in Josephson junctions with barriers of the ferromagnetic Heusler alloy Cu_2MnAl

摘要

We have studied Josephson junctions with barriers prepared from the Heusler compound Cu_2MnAl. In the as-prepared state the Cu_2MnAl layers are nonferromagnetic and the critical Josephson current density j_c decreases exponentially with the thickness of the Heusler layers d_F. On annealing the junctions at 240 ℃ the Heusler layers develop ferromagnetic order and we observe a dependence j_c(d_F) with j_c strongly enhanced and weakly thickness dependent in the thickness range 7.0