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Influence of Metal Interlayers on Spin-Charge Conversion in Sb2Te3 Topological Insulator-Based Devices
Emanuele Longo1, Matteo Belli2, Claudia Wiemer3
1Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra, Catalonia 08193, Spain.
Nano Letters
|April 18, 2025
Summary
Replacing gold with aluminum in topological insulator-ferromagnet heterostructures prevents spin-charge conversion. Aluminum
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spintronics
Background:
- Spin-charge conversion (SCC) in topological insulator (TI) heterostructures enables control of ferromagnetic layer magnetization.
- Nonmagnetic interlayers like gold (Au) can enhance SCC efficiency by preserving the TI's topological surface state (TSS).
Purpose of the Study:
- To investigate aluminum (Al) as an alternative interlayer to gold (Au) for enhancing SCC efficiency in Sb2Te3/Al/Co(Fe) heterostructures.
- To elucidate the role of material chemistry and the topological surface state (TSS) in mediating SCC.
Main Methods:
- Fabrication of Sb2Te3/Al/Co(Fe) and Sb2Te3/Au/Co(Fe) heterostructures.
- Spin pumping experiments to measure SCC efficiency.
- Core level and valence band photoemission spectroscopy to analyze interface chemistry and TSS preservation.
Main Results:
- Spin pumping experiments showed no SCC in the Sb2Te3/Al/Co heterostructure.
- Photoemission spectroscopy revealed that Al forms stable compounds with Sb and Te, quenching the TSS.
- The Sb2Te3/Au interface preserved the TSS, consistent with efficient SCC.
Conclusions:
- Aluminum interlayers are unsuitable for TI-based SCC devices due to chemical reactions that quench the TSS.
- Material chemistry at the interface critically influences TSS preservation and SCC efficiency.
- The topological surface state (TSS) is essential for efficient spin-charge conversion in these devices.
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