Superconducting and magnetic proximity effects in an epitaxial superconductor/ferromagnetic-semiconductor heterostructure consisting of Al/InAs/(Ga,Fe)Sb
ORAL
Abstract
Superconductor/ferromagnetic-semiconductor (FMS) heterostructures provide a compelling platform for quantum computing, owing to their electrically tunable superconducting and magnetic properties. In this study, we investigate epitaxial Al/InAs/(Ga,Fe)Sb heterostructures grown by molecular beam epitaxy (MBE) [1], in which we can control the spin-splitting in the InAs channel induced by the magnetic proximity from the adjacent FMS (Ga,Fe)Sb layer [2][3].
The examined heterostructure consists of Al (10 nm) / (In,Ga)As (5 nm) / InAs (15 nm)/(Ga,Fe)Sb (20 nm, doped with 14.6% Fe) grown by MBE. We fabricated planar Josephson junctions with superconducting Al electrodes and a 100 nm-long InAs/(Ga,Fe)Sb channel. These junctions exhibit zero resistance and multiple Andreev reflections, indicating the transparent interface between Al and the InAs channel. When a perpendicular magnetic field is applied, Fraunhofer patterns with hysteresis were observed, which reverse depending on the magnetic-field sweep direction. The Fraunhofer pattern shows a slight skew reminiscent of φ₀-junctions, suggesting broken time-reversal symmetry in the superconducting channel. These findings motivate further systematic exploration of the interplay between superconductivity and magnetism at the nanoscale.
[1] J. Shabani et al., Phys. Rev. B 93, 155402 (2016). [2] K. Takiguchi et al., Nat. Phys. 15, 1134 (2019). [3] H. Shiratani et al., Commun. Phys. 7, 6 (2024).
The examined heterostructure consists of Al (10 nm) / (In,Ga)As (5 nm) / InAs (15 nm)/(Ga,Fe)Sb (20 nm, doped with 14.6% Fe) grown by MBE. We fabricated planar Josephson junctions with superconducting Al electrodes and a 100 nm-long InAs/(Ga,Fe)Sb channel. These junctions exhibit zero resistance and multiple Andreev reflections, indicating the transparent interface between Al and the InAs channel. When a perpendicular magnetic field is applied, Fraunhofer patterns with hysteresis were observed, which reverse depending on the magnetic-field sweep direction. The Fraunhofer pattern shows a slight skew reminiscent of φ₀-junctions, suggesting broken time-reversal symmetry in the superconducting channel. These findings motivate further systematic exploration of the interplay between superconductivity and magnetism at the nanoscale.
[1] J. Shabani et al., Phys. Rev. B 93, 155402 (2016). [2] K. Takiguchi et al., Nat. Phys. 15, 1134 (2019). [3] H. Shiratani et al., Commun. Phys. 7, 6 (2024).
*This work was supported in part by the Grants-in-Aid for Scientific Research, the CREST program of JST, and the Spintronics Research Network of Japan (Spin-RNJ).
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Presenters
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Hirotaka Hara
- Univ of Tokyo