講演情報
[10p-N303-4]Epitaxial growth and characterization of a superconducting Sn/InSb heterostructure on a GaAs substrate
〇Shingen Miura1, Hirotaka Hara1, Hideki Maki1, Le Duc Anh1,2, Masaaki Tanaka1,2 (1.Univ. of Tokyo, 2.CSRN, Univ. of Tokyo)
キーワード：
superconductivity
Topological superconductivity has attracted significant attention as an essential research subject for realizing fault-tolerant topological quantum computers, owing to the potential existence of Majorana fermions that are protected from external disturbances. Theoretically, it has been predicted that a topological superconducting state can be induced through the superconducting proximity effect in heterojunction systems comprising superconductors and semiconductors with strong spin-orbit interaction.
In this study, we grew Sn/InSb heterostructures on GaAs substrates using molecular beam epitaxy (MBE) and studied their crystal structure and transport properties. The Sn layer exhibits superconductivity below 5 K, whose critical magnetic field and critical current exhibit twofold symmetry upon applying a rotating magnetic field: The superconducting critical current and magnetic field weaken when the in-plane magnetic field was applied parallel to the current direction, whereas it remained relatively large when the in-plane magnetic field was perpendicular to the current direction. This anisotropy cannot be explained solely by conventional β-Sn superconductivity, which follows the BCS theory. Additionally, in XRD measurements we observed peaks corresponding to both α-Sn and β-Sn. It is known that when α-Sn, a topological Dirac semimetal, exhibits superconductivity, it can become a topological superconductor. These results suggest that our Sn film contains both α-Sn and β-Sn, and the α-Sn regions might become superconducting through the superconducting proximity effect from the neighboring β-Sn regions, which could potentially exhibit topological superconductivity.
In this study, we grew Sn/InSb heterostructures on GaAs substrates using molecular beam epitaxy (MBE) and studied their crystal structure and transport properties. The Sn layer exhibits superconductivity below 5 K, whose critical magnetic field and critical current exhibit twofold symmetry upon applying a rotating magnetic field: The superconducting critical current and magnetic field weaken when the in-plane magnetic field was applied parallel to the current direction, whereas it remained relatively large when the in-plane magnetic field was perpendicular to the current direction. This anisotropy cannot be explained solely by conventional β-Sn superconductivity, which follows the BCS theory. Additionally, in XRD measurements we observed peaks corresponding to both α-Sn and β-Sn. It is known that when α-Sn, a topological Dirac semimetal, exhibits superconductivity, it can become a topological superconductor. These results suggest that our Sn film contains both α-Sn and β-Sn, and the α-Sn regions might become superconducting through the superconducting proximity effect from the neighboring β-Sn regions, which could potentially exhibit topological superconductivity.