Presentation Information
[10p-N303-9]Superconducting proximity effect in an in-situ grown heterostructure consisting of superconductor Al / InAs / ferromagnetic semiconductor (Ga,Fe)Sb
〇Hirotaka Hara1, Lukas Baker2, Shingen Miura1, Keita Ishihara1, Melissa Mikalsen2, Patrick Strohbeen2, Jacob Issokson2, Masaaki Tanaka1,3,4, Javad Shabani2, Le Duc Anh1,3 (1.EEIS, Univ. of Tokyo, 2.CQIP, New York Univ., 3.CSRN, Univ. of Tokyo, 4.Nano Quine, Univ. of Tokyo)
Keywords:
ferromagnetic semiconductor,superconducting proximity effect,Josephson junction
Superconductor / ferromagnetic semiconductor heterostructures provide a compelling platform for both fundamental research and emerging device applications, owing to their electrically tunable superconducting and magnetic properties. In this study, we investigate heterostructures comprising a superconducting Al layer, a nonmagnetic semiconductor InAs quantum well, and a ferromagnetic semiconductor (Ga,Fe)Sb layer. These heterostructures are particularly attractive due to their capability for in situ epitaxial growth, and the tunable spin-splitting in the InAs channel induced by the magnetic proximity from the adjacent (Ga,Fe)Sb layer.
The heterostructure consists of Al (10 nm)/(In,Ga)As (5 nm)/InAs (15 nm)/(Ga,Fe)Sb (20 nm, 14.6% Fe), grown by molecular beam epitaxy. Epitaxial growth of Al directly on the III-V semiconductor layers yields superconductivity below 1.3 K. Using this platform, we fabricated planar Josephson junctions with superconducting Al electrodes and a 100 nm-long InAs/(Ga,Fe)Sb channel. These junctions exhibit a zero-resistance state and clear Fraunhofer interference patterns, which display magnetic-field sweep-direction hysteresis and multiple flux jumps—signatures indicative of proximity-induced superconductivity in the magnetized InAs layer. A detailed analysis of the Fraunhofer patterns reveals node lifting and even/odd modulation, suggesting the presence of superconducting edge-channel transport within the InAs quantum well. This interpretation is consistent with previous studies on InAs/(Ga,Fe)Sb hybrid systems. These findings point to the emergence of unconventional superconducting transport modes and highlight the rich physics enabled by magnetic proximity effects in superconductor/ferromagnet hybrid structures. Our results motivate further systematic exploration of these hybrid systems to fully understand the interplay between magnetism and superconductivity at the nanoscale.
The heterostructure consists of Al (10 nm)/(In,Ga)As (5 nm)/InAs (15 nm)/(Ga,Fe)Sb (20 nm, 14.6% Fe), grown by molecular beam epitaxy. Epitaxial growth of Al directly on the III-V semiconductor layers yields superconductivity below 1.3 K. Using this platform, we fabricated planar Josephson junctions with superconducting Al electrodes and a 100 nm-long InAs/(Ga,Fe)Sb channel. These junctions exhibit a zero-resistance state and clear Fraunhofer interference patterns, which display magnetic-field sweep-direction hysteresis and multiple flux jumps—signatures indicative of proximity-induced superconductivity in the magnetized InAs layer. A detailed analysis of the Fraunhofer patterns reveals node lifting and even/odd modulation, suggesting the presence of superconducting edge-channel transport within the InAs quantum well. This interpretation is consistent with previous studies on InAs/(Ga,Fe)Sb hybrid systems. These findings point to the emergence of unconventional superconducting transport modes and highlight the rich physics enabled by magnetic proximity effects in superconductor/ferromagnet hybrid structures. Our results motivate further systematic exploration of these hybrid systems to fully understand the interplay between magnetism and superconductivity at the nanoscale.