Fig. 3

Junction transport in the virgin and conditioned states. a Resistance as a function of temperature, measured using 10 μA, before (pink) and after (navy) conditioning the sample. Each set shows two distinct transitions. At T = 5.5 K, the Nb electrodes become superconducting, while the junction is still in the normal state (R _N ≈ 240 mΩ). Upon cooling further, resistance undergoes a second transition as the barrier begins to proximize by triplet correlations—eventually reaching zero resistance. For clarity, the R−T dependence at lower temperatures is plotted on a logarithmic scale in the inset. While the superconducting electrodes are unaffected by conditioning the ferromagnets, we observe substantial enhancement of superconductivity in the barrier. b, c I−V traces taken at several temperatures before and after conditioning the sample, respectively. The pronounced contrast between the two sets indicates that transport depends strongly on the magnetic configuration of the junction