40 research outputs found
Accessing the Intrinsic Spin Transport in a Topological Insulator by Controlling the Crossover of Bulk-to-Surface Conductance
We report a method to control contributions of bulk and surface states in the topological insulator Bi2Te2Se that allows accessing the spin-polarized transport endowed by topological surface states. An intrinsic surface dominant transport is established when cooling the sample to low temperature or reducing the conduction channel length, both achieved in situ in the transport measurements with a four-probe scanning tunneling microscope without the need of further tailoring the sample. The topological surface states show characteristic transport behaviors with mobility about an order of magnitude higher than reported before, and a spin polarization approaching the theoretically predicted value. Our result demonstrates accessibility to the intrinsic high mobility spin transport of topological surface states, which paves a way to realizing topological spintronic devices. © 2018 American Physical Societ
Interplay between Topological States and Rashba States as Manifested on Surface Steps at Room Temperature
The unique spin texture of quantum states in topological materials underpins
many proposed spintronic applications. However, realizations of such great
potential are stymied by perturbations, such as temperature and local fields
imposed by impurities and defects, that can render a promising quantum state
uncontrollable. Here, we report room-temperature observation of interaction
between Rashba states and topological surface states, which manifests unique
spin textures controllable by layer thickness of thin films. Specifically, we
combine scanning tunneling microscopy/spectroscopy with the first-principles
theoretical calculation to find the robust Rashba states coexisting with
topological surface states along the surface steps with characteristic spin
textures in momentum space. The Rashba edge states can be switched off by
reducing the thickness of a topological insulator Bi2Se3 to bolster their
interaction with the hybridized topological surface states. The study unveils a
manipulating mechanism of the spin textures at room temperature, reinforcing
the necessity of thin film technology in controlling quantum states