Tuning the interfacial spin-orbit coupling with ferroelectricity

Detection and manipulation of spin current lie in the core of spintronics. Here we report an active control of a net spin Hall angle, θ_SHE(net), in Pt at an interface with a ferroelectric material PZT (PbZr_0.2Ti_0.8O₃), using its ferroelectric polarization. The spin Hall angle in the ultra-thin Pt layer is measured using the inverse spin Hall effect with a pulsed tunneling current from a ferromagnetic La_0.67Sr_0.33MnO₃ electrode. The effect of the ferroelectric polarization on θ_SHE(net) is enhanced when the thickness of the Pt layer is reduced. When the Pt layer is thinner than 6 nm, switching the ferroelectric polarization even changes the sign of θ_SHE(net). This is attributed to the reversed polarity of the spin Hall angle in the 1^st-layer Pt at the PZT/Pt interface when the ferroelectric polarization is inverted, as supported by the first-principles calculations. These findings suggest a route for designing future energy efficient spin-orbitronic devices using ferroelectric control.