Spin transfer torque oscillator based on asymmetric magnetic tunnel junctions

TL;DR

This paper investigates a spin transfer torque oscillator using asymmetric magnetic tunnel junctions, demonstrating high-frequency signal generation at the nanoscale without external magnetic fields, with potential applications in spintronic devices.

Contribution

The study introduces a nanoscale spin transfer torque oscillator leveraging asymmetric MTJs with ferromagnetic coupling and interface anisotropy, enabling high-frequency operation without external magnetic fields.

Findings

Microwave precession observed in junctions with varying free layer thickness.

Device generates signals exceeding 10 nV/Hz^0.5 at 1.5 GHz.

High-frequency oscillation achieved without external magnetic field.

Abstract

We present a study of the spin transfer torque oscillator based on CoFeB/MgO/CoFeB asymmetric magnetic tunnel junctions. We observe microwave precession in junctions with different thickness of the free magnetization layer. Taking advantage of the ferromagnetic interlayer exchange coupling between the free and reference layer in the MTJ and perpendicular interface anisotropy in thin CoFeB electrode we demonstrate the nanometer scale device that can generate high frequency signal without external magnetic field applied. The amplitude of the oscillation exceeds 10 nV/Hz^0.5 at 1.5 GHz.