Fig. 4: Tuning of the temperature behavior of the critical current in presence of an external magnetic field.

Normalized critical current I_c(T, H/H₀)/I_c(0.3 K, H/H₀) density plots as a function of the percentage of magnetic field periodicity H/H₀ and the temperature T, for the Josephson junctions with GdN thickness (a) d_F = 3.0 nm and (b) d_F = 3.5 nm. The critical current I_c values at each temperature T are measured by fixing the external magnetic field to H/H₀, where H₀ is the amplitude of the first lobe of the Fraunhofer pattern measured at the same temperature T. More details can be found in the Methods section “Experimental I_c(T) curves at zero- and finite-field”. Blue, red, and green lines refer to the cross-sections reported in (c) and (d): blue squares for H/H₀ = 0%, red circles for H/H₀ = 75% in (c) and H/H₀ = 65% in (d), green triangles for H/H₀ = 85% in (c) and H/H₀ = 75% in (d). Straight lines in plots (c) and (d) are only a guide for the eye. The error bar on each measured point is of the order of few percent and it is due to thermally induced I_c fluctuations³⁴. The white dashed arrows in (a) and (b) are a guide for the eye and highlight the shift of the minimum in the I_c(T, H/H₀)/I_c(0.3 K, H/H₀) by increasing H/H₀.