Dependence of spin torque diode voltage on applied field direction

TL;DR

This paper theoretically determines how the direction of an applied magnetic field affects the maximum spin torque diode voltage in a magnetic tunnel junction, with findings confirmed by numerical simulations.

Contribution

It derives the optimal applied field direction for maximizing diode voltage in a specific magnetic tunnel junction configuration, revealing how this optimum shifts with field strength.

Findings

Maximum diode voltage occurs when the field projection is parallel or anti-parallel at small fields.

Optimal field direction shifts as the applied field magnitude increases.

Numerical simulations confirm the analytical predictions.

Abstract

The optimum condition of an applied field direction to maximize spin torque diode voltage was theoretically derived for a magnetic tunnel junction with a perpendicularly magnetized free layer and an in-plane magnetized pinned layer. We found that the diode voltage for a relatively small applied field is maximized when the projection of the applied field to the film-plane is parallel or anti-parallel to the magnetization of the pinned layer. However, by increasing the applied field magnitude, the optimum applied field direction shifts from the parallel or anti-parallel direction. These analytical predictions were confirmed by numerical simulations.