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Research Highlight

“Channeling” Electrons to a Topological State for Ultrahigh Mobility of Spin Current

A schematic of spin-polarized four-probe scanning tunneling microscopy to measure spin-dependent electrical conductance on the topological insulator Bi2Te2Se. By reducing the probe spacing at low temperature, most electrons are “channeled” to the topological surface states, showing a quasi-ballistic spin-polarized conductance.

Scientific Achievement

Spin transport without scattering is achieved over micrometers by “channeling” electrons to topological surface states through limiting the crossover to bulk conductance.

Significance and Impact

Direct access to intrinsic spin transport with a record high mobility in topological insulators paves the way to low energy topological and spintronic devices. 

Research Details

- A spin-polarized four-probe scanning tunneling microscope is used to measure spin transport in topological insulator Bi2Te2Se.

- The crossover of bulk-to-surface conductance is tuned by controlling the probe-spacing and temperature in situ.


W. Ko, G. D. Nguyen, H. Kim, J. S. Kim, X. G. Zhang, and  A.-P. Li, "Accessing the intrinsic spin transport in a topological insulator by controlling the crossover of bulk-to-surface conductance," Phys. Rev. Lett121, 176801 (2018).  DOI: 10.1103/PhysRevLett.121.176801