Gate-Tunable Current-Induced Spin Polarization In Ultra Thin Topological Insulators Film With Surface Gap Opening.
Chun-Ming Fan Chiang1*, Cheong-Wei Chong1, J.C.A. Huang1
1Department of Physics, National Cheng Kung University, Tainan, Taiwan
* presenting author:Chun-Ming Fan Chiang,
Topological insulator (TI) has an unusual insulating bulk but metallic surface state which can lead to a dissipationless transport. The spin texture is helical around the surface Dirac cone and locked at right angle with the carriers’ momentum. In this work, we fabricated single crystal topological insulators thin films on sapphire, SiO₂/Si and SrTiO₃. We made a spin-valve-like device to detect the current-induced spin polarization due to spin-momentum locking. Below the characteristic thickness (6nm), TIs’ top and bottom surface coupled together which opened the Dirac surface gap. Fermi level could be tunable by applying the gate voltage. Among those three different substrates, we can compare the thickness, crystal structure, transport and field effect.

Keywords: Topological insulator, Thin film, Surface coupling, Transport, FET