Control over the ISHE in a platinum film by ionic gating

We report reversible modulation of the inverse spin Hall effect (ISHE) in Pt achieved through the careful control of Pt thickness and an ionic gating technique. The ISHE converts spin current into charge current, which allows easy detection of spin current and integration of spintronics and electronics. The effect is governed by spin-orbit interaction and is particularly strong in Pt, which has been widely used as the ISHE-based spin current detector. However, the gate tuning of the spin-orbit interaction in metals was considered out of reach because of high carrier density.

We fabricated Pt films, 1.5 nm to 20 nm thick, on top of the YIG ferrimagnetic layer and used spin pumping to inject spin current in the Pt layer. Using the the ionic gel (DEME-TFSI) top gate, the resistance of the Pt film was tuned up to 280%. Such control over the resistance and carrier density in Pt allowed us to gate tune the amplitude of the ISHE over two orders of magnitude—a result that can be used in spin-torque and other spintronics devices that use spin-charge conversion [1].

[1] S. Dushenko, M. Hokazono, M. Shiraishi et al., Tunable inverse spin Hall effect in nanometer-thick platinum films by ionic gating, Nat. Commun. 9, 3118 (2018).