Single spin-torque vortex oscillator using combined bottom-up approach and e-beam lithography

TL;DR

This paper presents a novel combined bottom-up and lithography method to create a single spin-torque vortex oscillator with tunable microwave emission at zero magnetic field, aligning well with theoretical models.

Contribution

It introduces a new fabrication approach for spin-torque vortex oscillators and demonstrates their microwave emission and tunability at zero magnetic field.

Findings

Microwave signals emitted at zero magnetic field.

Frequency tunability of 0.4 - 2 MHz/Oe based on magnetic field orientation.

Good agreement with analytical and micromagnetic models.

Abstract

A combined bottom-up assembly of electrodeposited nanowires and electron beam lithography technique has been developed to investigate the spin transfer torque and microwave emission on specially designed nanowires containing a single Co/Cu/Co pseudo spin valve. Microwave signals have been obtained even at zero magnetic field. Interestingly, high frequency vs. magnetic field tunability was demonstrated, in the range 0.4 - 2 MHz/Oe, depending on the orientation of the applied magnetic field relative to the magnetic layers of the pseudo spin valve. The frequency values and the emitted signal frequency as a function of the external magnetic field are in good quantitative agreement with the analytical vortex model as well as with micromagnetic simulations.