Spin-Torque Diode Measurements of MgO-Based Magnetic Tunnel Junctions with Asymmetric Electrodes

TL;DR

This study investigates the spin-torque diode effect in MgO-based magnetic tunnel junctions with asymmetric electrodes, highlighting the role of out-of-plane torque and its impact on device sensitivity for microwave detection.

Contribution

It provides detailed experimental analysis and simulations of resonance modes, emphasizing the significance of out-of-plane torque in asymmetric magnetic tunnel junctions.

Findings

Identification of free-layer resonance mode

Large out-of-plane torque contribution

Enhanced microwave detection sensitivity

Abstract

We present a detailed study of the spin-torque diode effect in CoFeB/MgO/CoFe/NiFe magnetic tunnel junctions. From the evolution of the resonance frequency with magnetic field at different angles, we clearly identify the free-layer mode and find an excellent agreement with simulations by taking into account several terms for magnetic anisotropy. Moreover, we demonstrate the large contribution of the out-of-plane torque in our junctions with asymmetric electrodes compared to the in-plane torque. Consequently, we provide a way to enhance the sensitivity of these devices for the detection of microwave frequency.