Current induced resistance change of magnetic tunnel junctions with ultra-thin MgO tunnel barriers

TL;DR

This study investigates how ultra-thin MgO-based magnetic tunnel junctions respond to large current stress, revealing reversible resistance changes and underlying relaxation processes through experimental analysis and modeling.

Contribution

It provides a detailed analysis of current-induced resistance changes in ultra-thin MgO tunnel barriers, introducing a simple model to explain the observed reversible phenomena.

Findings

Reversible resistance change under large current stress

Identification of two stress-related processes and one relaxation process

Quantification of timescales for the involved phenomena

Abstract

Ultra-thin magnetic tunnel junctions with low resistive MgO tunnel barriers are prepared to examine their stability under large current stress. The devices show magnetoresistance ratios of up to 110 % and an area resistance product of down to 4.4 ohm micrometer squared. If a large current is applied, a reversible resistance change is observed, which can be attributed to two different processes during stressing and one relaxation process afterwards. Here, we analyze the time dependence of the resistance and use a simple model to explain the observed behavior. The explanation is further supported by numerical fits to the data in order to quantify the timescales of the involved phenomena.