Atomic scale image transition in a high-Tc superconductor/ferromagnetic-insulator/high-Tc superconductor Josephson junction

We study the Josephson transport in a high-Tc superconductor/ferromagnetic-insulator(FI)/high-Tc superconductor numerically. We found the formation of a π-junction in such systems. More remarkably the ground state of such junction alternates between 0- and π-states when thickness of FI is increasing by a single atomic layer. We propose an experimental setup for observing the atomic scale 0–π transition. Such FI-based π-junctions can be used to implement highly coherent quantum bits.