Interplay of superconductivity and ferromagnetism in ferromagnetic-semiconductor-based Josephson junctions

The interplay between superconductivity and ferromagnetism has long been pursued as a route to unconventional Josephson effects, yet suitable material platforms remain limited. Here we report Josephson junctions based on epitaxial Al/InAs/(Ga,Fe)Sb heterostructures grown by low-temperature molecular beam epitaxy, achieving atomically abrupt superconductor/semiconductor/ferromagnetic-semiconductor interfaces. The devices exhibit clear proximity-induced superconductivity, including multiple Andreev reflections and gate-tunable supercurrents, confirming transparent coupling across the hybrid structure. Under perpendicular magnetic fields, the junctions reveal highly unconventional Fraunhofer interference patterns with hysteresis, flux jumps, asymmetric lobe evolution, and clear nonreciprocity, which are consistent with induced ferromagnetism and broken time-reversal symmetry, and may also indicate the presence of edge-channel transport in the Josephson junctions. Our results demonstrate that ferromagnetic semiconductor heterostructures can serve as a highly tunable platform for exploring proximity-induced superconductivity and superconducting diode effects, and for advancing device concepts at the intersection of magnetism and quantum electronics. The interplay between superconductivity and ferromagnetism offers a pathway to unconventional Josephson effects and novel superconducting device applications, yet suitable materials are scarce. Here, the authors utilize epitaxial Al/InAs/(Ga,Fe)Sb heterostructures to achieve atomically precise interfaces, revealing proximity-induced superconductivity and unconventional Fraunhofer patterns consistent with induced ferromagnetism and edge-channel superconducting transport.