[16p-D704-1~18] 10.4 Spintronics in semiconductor, topological material, superconductor, and multiferroics

▼ [16p-D704-13] Nanofabrication of Sn-based superconductor / topological Dirac semimetal planar heterostructures

〇Keita Ishihara¹, Le Duc Anh^1,2,3, Tomoki Hotta¹, Kohdai Inagaki¹, Masaki Kobayashi^1,3, Masaaki Tanaka^1,3 (1.Graduate School of Electrical Engineering and Information System, The University of Tokyo, 2.PRESTO, JST, 3.Center for Spintronics Research Network)

Keywords:Dirac semimetal, Superconductor

Heterostructures of superconductor/topological materials attract attention as a platform of unconventional superconductivity. Among various topological material candidates, α-Sn is attractive because it can exhibit a wide range of topological phases from topological Dirac semimetal to topological insulator . Moreover, upon heating α-Sn undergoes a phase transition to β-Sn, which becomes superconducting at low temperature (< 4 K). We grew epitaxial 40 nm-thick α-Sn thin films with diamond-type crystal structure grown on InSb (001) substrates by molecular beam epitaxy (MBE). By focusing the ion beam, we successfully fabricated β-Sn nanowire with width t = 180 nm. We found that the β-Sn nanowires of various t exhibit superconductivity below 4 K and the critical temperature depends on t. The microscopic structures of the β-Sn/α-Sn were characterized using scanning electron microscopy (SEM), transmission electron microscopy and X-ray photoemission spectroscopy, indicating the formation of β-Sn areas and good β-Sn/α-Sn interfaces inside the α-Sn thin films due to local heating.