Steady State and Dynamics of Joule Heating in Magnetic Tunnel Junctions Observed via the Temperature Dependence of RKKY Coupling

TL;DR

This paper introduces a novel method to measure and analyze the heating dynamics in magnetic tunnel junctions using RKKY coupling as a thermal sensor, crucial for advancing MRAM technology.

Contribution

A new technique to quantify and distinguish heating effects in MTJs using RKKY coupling, enabling real-time analysis of thermal dynamics during device operation.

Findings

RKKY coupling decreases with temperature, serving as a thermal sensor.

The method distinguishes between spin transfer torque effects and thermal influences.

Real-time measurement of heating dynamics during device operation.

Abstract

Understanding quantitatively the heating dynamics in magnetic tunnel junctions (MTJ) submitted to current pulses is very important in the context of spin-transfer-torque magnetic random access memory development. Here we provide a method to probe the heating of MTJ using the RKKY coupling of a synthetic ferrimagnetic storage layer as a thermal sensor. The temperature increase versus applied bias voltage is measured thanks to the decrease of the spin-flop field with temperature. This method allows distinguishing spin transfer torque (STT) effects from the influence of temperature on the switching field. The heating dynamics is then studied in real-time by probing the conductance variation due to spin-flop rotation during heating. This approach provides a new method for measuring fast heating in spintronic devices, particularly magnetic random access memory (MRAM) using thermally assisted or spin transfer torque writing.