Spin-torque switching in large size nano-magnet with perpendicular magnetic fields

TL;DR

This study investigates spin-torque induced magnetization reversal and oscillation in large 500 nm CoFe/Cu/NiFe pillars, demonstrating how external magnetic fields and bias currents influence magnetic dynamics, with implications for enhancing spin-torque oscillator power.

Contribution

It provides experimental and simulation insights into spin-torque switching and precession in large-sized nano-magnets, a less explored regime compared to smaller devices.

Findings

Magnetization reversal observed in large pillars under DC current.

External perpendicular magnetic field enhances coercive field separation.

Micromagnetic simulations agree with experimental results.

Abstract

DC current induced magnetization reversal and magnetization oscillation was observed in 500 nm large size Co90Fe10/Cu/Ni80Fe20 pillars. A perpendicular external field enhanced the coercive field separation between the reference layer (Co90Fe10) and free layer (Ni80Fe20) in the pseudo spin valve, allowing a large window of external magnetic field for exploring the free-layer reversal. The magnetization precession was manifested in terms of the multiple peaks on the differential resistance curves. Depending on the bias current and applied field, the regions of magnetic switching and magnetization precession on a dynamical stability diagram has been discussed in details. Micromagnetic simulations are shown to be in good agreement with experimental results and provide insight for synchronization of inhomogenieties in large sized device. The ability to manipulate spin-dynamics on large size devices could prove useful for increasing the output power of the spin-transfer nano-oscillators (STNOs).