Large-angle, gigahertz-rate random telegraph switching induced by spin-momentum transfer

TL;DR

This paper demonstrates that spin-polarized current can induce high-speed, random magnetization switching in small magnetic elements, with rates exceeding 2 GHz, driven by spin-momentum transfer effects.

Contribution

It reveals that spin-momentum transfer causes gigahertz-rate telegraph switching in magnetic nanostructures, a phenomenon not previously characterized at this scale and speed.

Findings

Switching rates exceed 2 GHz.

Resistance states differ by up to 50%.

Fluctuations occur over a wide range of currents and fields.

Abstract

We show that spin-polarized dc current passing through a small magnetic element induces two-state, random telegraph switching of the magnetization via the spin-momentum transfer effect. The resistances of the states differ by up to 50% of the change due to complete magnetization reversal. Fluctuations are seen for a wide range of currents and magnetic fields, with rates that can exceed 2 GHz, and involve collective motion of a large volume (10^4 nm^3) of spins. Switching rate trends with field and current indicate that increasing temperature alone cannot explain the dynamics. The rates approach a stochastic regime wherein dynamics are governed by both precessional motion and thermal perturbations.