[16p-Z35-1~8] 9.5 New functional materials and new phenomena

△ [16p-Z35-1] Quantum transport of surface and bulk states with high mobility in elemental topological insulator α -Sn

〇(M2)Kengo Takase¹, Le Duc Anh^1,2,3, Kosuke Takiguchi¹, Masaaki Tanaka^1,4 (1.EEIS, Univ. of Tokyo, 2.IEI, Univ. of Tokyo, 3.PRESTO, JST, 4.CSRN, Univ. of Tokyo)

Keywords:topological insulator, alpha Sn, quantum oscillation

Strained α -Sn is one of the firstly known three-dimensional TI that is composed of single element. In this study, we grew high quality single-crystal α -Sn thin films and study their quantum transport. α -Sn thin films of 9.2 nm are epitaxially grown on InSb(001) substrates by molecular beam epitaxy (MBE). The clear Shubnikov-de Hass (SdH) oscillations revealed three components, all of which show two-dimensional transport. We observed a surface state of α -Sn with a light cyclotron mass (~ 0.035 m₀) and nontrivial Berry phase (~ -0.62π), whose quantum mobility reaches about 24000 cm²/Vs that is ten-times higher than that in previous reports. A heavy-hole-like state of α -Sn with a relatively heavy cyclotron mass (~ 0.12 m₀) was observed for the first time in quantum transport, whose nontrivial Berry phase (~ 0.54π) suggests its hybridization with the surface state. We also studied thickness-dependence of the α -Sn band structure.