Superconducting diodes, characterized by the nonreciprocal supercurrent flow, have gained significant attention for their potential in dissipationless electronics. This study presents a superconducting quantum interference device (SQUID) composed of two Al-InSb nanosheet Josephson junctions. Utilizing prepatterned local backgates, we achieve a gate- and flux-tunable superconducting diode with controllable efficiency in both amplitude and sign. Numerical simulations attribute the diode effect to higher harmonics in the current-phase relation. Crucially, fractional Shapiro step experiments provide direct insights into the evolution of these higher harmonics with flux tuning, showcasing significant enhancements in the second-harmonic signatures of the SQUID near half-integer flux quanta. Furthermore, we investigate the microwave-assisted diode response and experimentally show that the polarity of the diode effect can be switched by the microwave power. These results demonstrate the potential of InSb nanosheet-based hybrid devices as highly tunable elements for use in dissipationless electronics.
@article{arxiv.2502.13391,
title = {Tunable superconducting diode effect in higher-harmonic InSb nanosheet interferometers},
author = {Xingjun Wu and Ji-Yin Wang and Haitian Su and Shili Yan and Dong Pan and Jianhua Zhao and Po Zhang and H. Q. Xu},
journal= {arXiv preprint arXiv:2502.13391},
year = {2025}
}