Rectification of radio frequency current in giant magnetoresistance spin valve

TL;DR

This paper demonstrates a highly efficient spin diode effect in GMR spin-valve strips caused by asymmetric current distribution and resulting Oersted fields, with theoretical and experimental analysis showing strong rectification signals.

Contribution

It provides a theoretical model and experimental validation for the rectification of RF current in GMR spin valves due to asymmetric current distribution and Oersted fields, highlighting enhanced spin diode signals.

Findings

Quantitative agreement between theory and experiment.

Significantly stronger spin diode signals than in permalloy-based devices.

Dependence of the signal on frequency, magnetic field, and angle.

Abstract

We report on a highly efficient spin diode effect in an exchange-biased spin-valve giant magnetoresistance (GMR) strips. In such multilayer structures, symmetry of the current distribution along the vertical direction is broken and, as a result, a non-compensated Oersted field acting on the magnetic free layer appears. This field, in turn, is a driving force of magnetization precessions. Due to the GMR effect, resistance of the strip oscillates following the magnetization dynamics. This leads to rectification of the applied radio frequency current and induces a direct current voltage $V_{DC}$. We present a theoretical description of this phenomenon and calculate the spin diode signal, $V_{DC}$, as a function of frequency, external magnetic field, and angle at which the external field is applied. A satisfactory quantitative agreement between theoretical predictions and experimental data has been achieved. Finally, we show that the spin diode signal in GMR devices is significantly stronger than in the anisotropic magnetoresistance permalloy-based devices.