Large amplitude microwave emission and reduced nonlinear phase noise in Co2Fe(Ge0.5Ga0.5) Heusler alloy based pseudo spin valve nanopillars

TL;DR

This study investigates microwave emission from Co2Fe(Ga0.5Ge0.5) Heusler alloy-based pseudo spin valve nanopillars, revealing large amplitude, narrow linewidth, and insights into nonlinear phase noise effects on linewidth broadening.

Contribution

It demonstrates large microwave emission amplitude and linewidth reduction in Heusler alloy spin valves, and correlates linewidth behavior with nonlinear phase noise predictions.

Findings

Emission amplitude exceeds 150 nV/Hz^0.5

Linewidth below 10 MHz observed

Linewidth depends on field magnitude and angle

Abstract

We have studied microwave emission from a current-perpendicular-to-plane pseudo spin valve nanopillars with Heusler alloy Co2Fe(Ga0.5Ge0.5) electrodes. Large emission amplitude exceeding 150 nV/Hz^0.5, partly owing to the large magnetoresistance, and narrow generation linewidth below 10 MHz are observed. We also find that the linewidth shows significant dependence on the applied field magnitude and its angle within the film plane. A minimum in the linewidth is observed when the slope of the frequency versus current becomes near zero. This agrees with theoretical prediction that takes into account non-linear phase noise as a source for linewidth broadening.