Electric field-controlled spin transport in a topological insulator interfaced with a ferroelectric antiferromagnet.

Electric-field control of spin-charge conversion in Bi2Te3/BiFeO3 is robust for Bi2Te3 thicknesses above 10 nanometers, but it rapidly decreases and vanishes at 5 nanometers.

• Why it matters: Spin-charge interconversion in topological insulators is well studied with magnetic interfaces, yet its electric-field response without an external magnetic field—and its thickness-limited regime—remained unclear.
• What they did: Using a nonlocal spin transport device, the authors measured thickness-dependent spin transport across the Bi2Te3/BiFeO3 interface and analyzed magnetoconductance to estimate a coherency factor.
• The result: The thickness trend indicates topological surface-state-dominated transport in the decoupled regime and is consistent with hybridization-induced emergence of a trivial insulating phase, enabling efficient conversion at an insulating magnetic interface.

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