Fig. 4: Unconventional Fraunhofer patterns as evidence of π phase coupling.

a 0-π junction like I_c oscillation patterns of device #02 with the magnetic field starts from ±30 mT at 0.1 K. Its barrier thickness is ~10.5 nm. The yellow dashed lines mark the valley positions of the central minimum of I_c to depict a 0-π junction behavior. b Hysteresis of I_c⁺ of device #02. The ΔB_max value is 3 mT estimated from the valley positions in the center. The difference of field widths around this valley indicates an asymmetric local magnetization of the barrier. c Origin of a π phase through the magnetic tunneling of Cooper pairs. The reversal of the spin-order involves the fourth-order co-tunneling process. d Illustration of a junction area with several π segments (perpendicular magnetizations) and 0 segments (tilted or parallel magnetizations). e Comparisons of I_c at the positive and negative bias of device #02 (left and right: opposite sweeping branches) to exclude the influence of trapped vortex. f Another 0-π junction signature of device #03 with a ~11-nm-thick barrier. The field starts from ±50 mT at 0.1 K, giving the ΔB_max value of 2 mT.