Gate Controlled Anomalous Phase Shift in Al/InAs Josephson Junctions
ORAL
Abstract
In a standard Josephson junction the current is zero when the phase difference between superconducting leads is zero. This condition is protected by parity and time-reversal symmetries. However, the combined presence of spin-orbit coupling, and in-plane magnetic field breaks these symmetries, which can lead to a finite supercurrent even when the phase difference is zero. This is the anomalous Josephson effect which can be characterized by the corresponding anomalous phase shift. We report the observation of a tunable anomalous Josephson effect in Al/InAs Josephson junctions measured via a superconducting quantum interference device. By gate controlling the density of InAs, we are able to tune the spin-orbit coupling in the Josephson junction. This gives us the ability to tune the anomalous phase using both in-plane magnetic field and gate voltage. We observe anomalous phase shifts larger than expected from theory for our material parameters. These results open new opportunities for superconducting spintronics, and new possibilities for realizing and characterizing topological superconductivity.
*This work is supported by DARPA Topological Excitations Grant No. DP18AP90000 in Electronics (TEE) program and NSF dmr 1836687. ER acknowledges support from NSF, ONR and ARO.
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Presenters
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William Mayer
- Department of Physics, New York University
- New York University
- Physics, New York University
- New York Univ NYU
- Center for Quantum Phenomena, New York University