Supercurrent and Multiple Andreev Reflections in InSb Nanosheet SNS Junctions

Abstract

In this study, the realization of mesoscopic Josephson junctions based on free-standing InSb nanosheet grown by molecular-beam epitaxy is reported. Below the critical temperature of superconducting aluminium electrodes (%1.1 K), the high transparency of the contacts gives rise to proximityinduced superconductivity. A dissipationless supercurrent which can be modulated by a gate voltage acting on the electron density in the nanosheet flows through the superconducting weak links. At finite bias voltage, subharmonic energy-gap structures (SGS) originating from multiple Andreev reflections (MARs) are observed, indicating a highly transparent InSb nanosheet-superconductor interface. At last, a superconducting hybrid device with niobium electrodes is shown, suitable for further higher temperature and magnetic field transport measurements.

Crossed Andreev reflection in InSb flake Josephson junctions

“…InSb is known for its large g-factor [16] and strong SOI [17], and earlier works referred to the flakes as nanosails [16] or nanosheets [18,19]. The InSb flakes are grown with the vapor-liquid-solid technique [20,21].…”

Strong and tunable spin–orbit interaction in a single crystalline InSb nanosheet

“…In comparison with InSb/InAlSb quantum well systems, the free-standing InSb nanosheets have advantages in direct contact by metals, including superconducting materials, in easy transfer to different substrates, and in convenient fabrication of dual-gate structures. With use of free-standing InSb nanosheets, lateral quantum devices, such as planar quantum dots 31 and superconducting Josephson junctions [32][33][34] , have been successfully fabricated. A most intriguing perspective of these layered materials is to build topological superconducting structures from them, in which Majorana fermions and parafermions 35,36 can be created and manipulated, enabling a different route of developments towards topological quantum computation technology.…”

Time-reversal invariant topological superconductivity in planar Josephson bijunction

“…Prominent experimental realizations involve nanowires proximitized by an s-wave superconductor [5][6][7][8][9], or chains of magnetic adatoms on s-wave superconductors [10][11][12][13][14][15][16][17][18]. More recently, MBSs in Josephson junctions [19] gained considerable interest [20][21][22][23][24][25][26][27][28][29][30], since this setup offers additional control knobs for experiments, in particular, the superconducting phase difference. In this case, the topological phase can be reached for a wide parameter range and the scalability to topological networks seems promising as the quality of materials is improving [19].…”