Direct visualization of current-induced spin accumulation in topological insulators

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics
• Topological Insulators

Background:

• Charge-to-spin conversion is fundamental for spin-orbitronics and magnetization control.
• Understanding spin accumulation at material interfaces is crucial for device applications.

Purpose of the Study:

• To directly image current-induced spin accumulation at the edges of Bi2Se3, BiSbTeSe2, and Pt.
• To investigate the properties and origins of spin accumulation in these materials.
• To explore optical detection methods for spin accumulation.

Main Methods:

• Utilized a scanning photovoltage microscope for spatial imaging of spin accumulation.
• Performed measurements at room temperature.
• Investigated the dependence of spin signal on current direction and magnitude.

Main Results:

• Successfully imaged current-induced spin accumulation at the channel edges of Bi2Se3, BiSbTeSe2, and Pt.
• Observed out-of-plane spin polarization with opposite signs at the two channel edges.
• Demonstrated that spin accumulation is a current-induced effect, with signal reversing upon current reversal and showing linear dependence on current magnitude.
• Quantified the spin Hall angles for Bi2Se3 (0.0085), BiSbTeSe2 (0.0616), and Pt (0.0085).

Conclusions:

• The study demonstrates a novel optical method for detecting current-induced spin accumulation.
• Results provide a deeper understanding of spin-orbit interactions in topological insulators and metals.
• The findings pave the way for advanced spintronic devices and studies on light-spin interactions.