Gate-tunable Josephson Junctions in a KTaO₃ Heterostructure

The observation of anisotropic superconductivity and strong Pauli-limit violation in KTaO3 (111) based heterostructures raises the question about the nature of the superconducting state. To better understand the origin of this state, devices which are sensitive to the phase of the superconducting order parameter are required, which would allow one to gain new insight into the contributing symmetries and to engineer physical devices. Here we present transport measurements of gate-tunable samples in which we are able to reversibly enhance and even completely suppress the critical current through a narrow constriction. Applying an out-of-plane magnetic field produces interference patterns with unexpected features that may indicate the influence of spin-orbit-coupling and ferromagnetism in this system. The devices are fabricated using a simple, versatile process which is also expected to be both cheap and scalable. These results help to establish KTaO3 (111) based heterostructures as a platform for the studying of unconventional superconductivity and for applications in the growing field of superconducting electronics.