title: Spin-filtered edge states with an electrically tunable gap in a two-dimensional topological crystalline insulator.
abstract: Three-dimensional topological crystalline insulators were recently predicted and observed in the SnTe class of IV-VI semiconductors, which host metallic surface states protected by crystal symmetries. In this work, we study thin films of these materials and expose their potential for device applications. We demonstrate that thin films of SnTe and Pb(1-x)Sn(x)Se(Te) grown along the (001) direction are topologically non-trivial in a wide range of film thickness and carry conducting spin-filtered edge states that are protected by the (001) mirror symmetry through a topological invariant. Application of an electric field perpendicular to the film will break the mirror symmetry and generate a bandgap in these edge states. This functionality motivates us to propose a topological transistor device in which charge and spin transport are maximally entangled and simultaneously controlled by an electric field. The high on/off operation speed and coupling of spin and charge in such a device may lead to electronic and spintronic applications for topological crystalline insulators.
authors.affiliation: 1] Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China [2] Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Junwei
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Hsieh
authors.affiliation: 1] Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA [2] Francis Bitter Magnet Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Peng
authors.initials: P
authors.lastname: Wei
authors.affiliation: Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China.
authors.forename: Wenhui
authors.initials: W
authors.lastname: Duan
authors.affiliation: 1] Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA [2] Francis Bitter Magnet Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Jagadeesh
authors.initials: J
authors.lastname: Moodera
authors.affiliation: Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Liang
authors.initials: L
authors.lastname: Fu