Protected 0-pi states in SIsFS junctions for Josephson memory and logic

We study the peculiarities in current-phase relations (CPR) of the SIsFS junction in the region of 0 to pi transition. These CPR consist of two independent branches corresponding to 0- and pi-states of the contact. We have found that depending on the transparency of the SIs tunnel barrier, the decrease in the s-layer thickness leads to transformation of the CPR shape going in the two possible ways: either one of the branches exists only in discrete intervals of the phase difference phi or both branches are sinusoidal but differ in the magnitude of their critical currents. We demonstrate that the difference can be as large as 10% under maintaining superconductivity in the s layer. An applicability of these phenomena for memory and logic application is discussed. Published by AIP Publishing.