Effects of delayed feedback on the power spectrum of spin-torque nano-oscillators

TL;DR

This paper presents a theoretical analysis of how delayed feedback influences the power spectrum of spin-torque nano-oscillators, revealing complex modulation effects and the impact of temperature on coherence.

Contribution

It introduces a theoretical model showing how delayed feedback modulates supercriticality and affects the power spectrum in spin-torque nano-oscillators, highlighting nonlinear and temperature effects.

Findings

Delayed feedback causes frequency modulation and sideband structures.

Finite temperature reduces the complexity of the modulation spectrum.

Strong nonlinearity influences the oscillator's response to feedback.

Abstract

A theoretical study of delayed feedback in a spin-torque nano-oscillator model is presented. The feedback acts as a modulation of the supercriticality, which results in changes in the oscillator frequency through a strong nonlinearity, amplitude modulations, and a rich modulation sideband structure in the power spectrum at long delays. Modulation sidebands persist at finite temperatures but some of the complex structure is lost through the finite coherence time of the oscillations.