Interface-driven spin-torque ferromagnetic resonance by Rashba coupling at the interface between non-magnetic materials

TL;DR

This paper demonstrates that a Bi/Ag Rashba interface can generate spin currents to induce ferromagnetic resonance in an adjacent layer, using a novel interface-driven spin-torque mechanism detected via anisotropic magnetoresistance.

Contribution

It introduces a new method for driving ferromagnetic resonance through interface-induced Rashba effects, expanding spintronics control techniques.

Findings

Bi/Ag Rashba interface generates spin currents.

Spin-torque ferromagnetic resonance observed in Py layer.

Electrical detection via anisotropic magnetoresistance.

Abstract

The Rashba-Edelstein effect stems from the interaction between the electron's spin and its momentum induced by spin-orbit interaction at an interface or a surface. It was shown that the inverse Rashba-Edelstein effect can be used to convert a spin- into a charge current. Here, we demonstrate that a Bi/Ag Rashba interface can even drive an adjacent ferromagnet to resonance. We employ a spin-torque ferromagnetic resonance excitation/detection scheme which was developed originally for a bulk spin-orbital effect, the spin Hall effect. In our experiment, the direct Rashba-Edelstein effect generates an oscillating spin current from an alternating charge current driving the magnetization precession in a neighboring permalloy (Py, Ni80Fe20) layer. Electrical detection of the magnetization dynamics is achieved by a rectification mechanism of the time dependent multilayer resistance arising from the anisotropic magnetoresistance.