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Direct comparison of current-induced spin polarization in topological insulator Bi2Se3 and InAs Rashba states
C H Li1, O M J van 't Erve1, S Rajput2
1Materials Science and Technology Division, Naval Research Laboratory, Washington, District of Columbia 20375, USA.
Nature Communications
|November 18, 2016
Summary
Three-dimensional topological insulators (TIs) show spin-momentum locking in their Dirac surface states. This study confirms Dirac surface states dominate spin polarization in TIs, even with coexisting trivial electron gas states.
Area of Science:
- Condensed matter physics
- Materials science
Background:
- Topological insulators (TIs) possess unique Dirac surface states with spin-momentum locking.
- Surface band bending can create coexisting trivial two-dimensional electron gas (2DEG) states.
Purpose of the Study:
- Compare bias current-generated spin polarization in a TI (Bi2Se3) and a conventional semiconductor (InAs).
- Investigate the contribution of Dirac surface states versus 2DEG states to spin polarization in TIs.
Main Methods:
- Spin potentiometric measurements were performed on Bi2Se3(111) and InAs(001) under bias current.
- A theoretical model based on spin-dependent electrochemical potentials was developed.
Main Results:
- Spin polarization was observed in both Bi2Se3 and InAs, originating from spin-momentum locking.
- Opposite signs of the measured spin voltage were detected between the two materials.
- The model successfully predicted the spin voltage sign for Dirac surface states.
Conclusions:
- Dirac surface states in topological insulators are the primary source of current-generated spin polarization.
- The findings highlight the distinct spin properties of topological surface states.
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