Abstract
Electric gating can strongly modulate a wide variety of physical properties in semiconductors and insulators, such as significant changes of conductivity in silicon, appearance of superconductivity in SrTiO3, the paramagnet–ferromagnet transition in (In,Mn)As, and so on. The key to such modulation is charge accumulation in solids. Thus, it has been believed that such modulation is out of reach for conventional metals where the number of carriers is too large. However, success in tuning the Curie temperature of ultrathin cobalt gave hope of finally achieving such a degree of control even in metallic materials. Here, we show reversible modulation of up to two orders of magnitude of the inverse spin Hall effect—a phenomenon that governs interconversion between spin and charge currents—in ultrathin platinum. Spin-to-charge conversion enables the generation and use of electric and spin currents in the same device, which is crucial for the future of spintronics and electronics.
Highlights
Electric gating can strongly modulate a wide variety of physical properties in semiconductors and insulators, such as significant changes of conductivity in silicon, appearance of superconductivity in SrTiO3, the paramagnet–ferromagnet transition in (In,Mn)As, and so on
While electric gating controls carrier density and directly influences conductivity of the material, it can be applied to control any property of the material that depends on the position of the Fermi level
In 2006, Saitoh et al converted the pure spin current into the electric charge current using the inverse spin Hall effect (ISHE) in metallic Pt layer[4], while Valenzuela et al detected the same effect in the aluminum channel of lateral spin valve[5]
Summary
Electric gating can strongly modulate a wide variety of physical properties in semiconductors and insulators, such as significant changes of conductivity in silicon, appearance of superconductivity in SrTiO3, the paramagnet–ferromagnet transition in (In,Mn)As, and so on. As discussed above, in contrast to semiconductors and two-dimensional systems, electric gating control over spin–charge conversion via ISHE in metals remained a formidable challenge. We report the largest to date modulation of the metal resistivity in ultrathin Pt film through the careful control of Pt thickness and an ionic gate technique We show that such control over the carrier density allowed us to tune reversibly and reproducibly the amplitude of the ISHE in Pt over two orders of magnitude—a result that can be used in spin-torque and other spintronics devices that use spin–charge conversion
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