Manifestation of π-contacts in magnetic field dependence of I-V characteristics for proximity-type 2D Josephson junction array

Results on the temperature and magnetic field dependence of current-voltage characteristics (CVC) are presented for SNS-type 2D ordered array of Nb-Cu0.95Al0.05-Nb junctions. The critical current IC(T,H) and the power exponent a(T,H)=1+Φ0IC(T,H)/2kBT of the nonlinear CVC law V=R[I−IC(T,H)]a(T,H) are found to have a maximum at non-zero value of applied magnetic field Hp=225Oe, which is attributed to manifestation of π-type Josephson contacts in our sample.