AVS 65th International Symposium & Exhibition
    Nanometer-scale Science and Technology Division Thursday Sessions
       Session NS+2D+AS+MN+PC-ThA

Paper NS+2D+AS+MN+PC-ThA6
Bulk and Surface Contribution to the Charge and Spin Transport in Topological Insulators Observed with a Four-Probe Scanning Tunneling Microscope

Thursday, October 25, 2018, 4:00 pm, Room 102B

Session: SPM – Probing Electronic and Transport Properties
Presenter: Wonhee Ko, Oak Ridge National Laboratory
Authors: W. Ko, Oak Ridge National Laboratory
G.D. Nguyen, Oak Ridge National Laboratory
H. Kim, Pohang University of Science and Technology, Republic of Korea
J.S. Kim, Pohang University of Science and Technology, Republic of Korea
A.-P. Li, Oak Ridge National Laboratory
Correspondent: Click to Email
Topological insulators are fascinating materials for future electronics because of its superior charge and spin transport characteristics stemming from their topological nature. However, topological insulators realized in actual materials have both bulk and surface carriers, where the former significantly hampers the topological transport of the later. In this talk, we utilize four-probe scanning tunneling microscope to investigate bulk and surface contribution to the charge and spin transport in bulk-insulating topological insulator Bi2Te2Se. The relative contribution of bulk and surface was varied by changing temperature and transport area, which was measured by variable probe-spacing spectroscopy. The surface dominant regime was already reached at 82 K, where the sample exhibited superior transport properties such as a large surface mobility and high spin polarization. At this regime, the contact to external probes also transforms from Schottky to Ohmic junction. Our result indicates that controlling bulk and surface contribution to the transport is crucial for realizing topological devices.