Current-induced magnetization switching in atom-thick tungsten engineered perpendicular magnetic tunnel junctions with large tunnel magnetoresistance

TL;DR

This paper demonstrates current-induced magnetization switching in atom-thick tungsten-based perpendicular magnetic tunnel junctions with high tunnel magnetoresistance and low resistance, advancing MRAM technology.

Contribution

It reports a novel atom-thick tungsten layer structure enabling efficient spin transfer torque switching with high magnetoresistance and low resistance area product.

Findings

Magnetoresistance ratio up to 249%

Resistance area product as low as 7.0 Ω·μm²

Switching current density below 3.0 MA/cm²

Abstract

Perpendicular magnetic tunnel junctions based on MgO/CoFeB structures are of particular interest for magnetic random-access memories because of their excellent thermal stability, scaling potential, and power dissipation. However, the major challenge of current-induced switching in the nanopillars with both a large tunnel magnetoresistance ratio and a low junction resistance is still to be met. Here, we report spin transfer torque switching in nano-scale perpendicular magnetic tunnel junctions with a magnetoresistance ratio up to 249% and a resistance area product as low as 7.0 {\Omega}.{\mu}m2, which consists of atom-thick W layers and double MgO/CoFeB interfaces. The efficient resonant tunnelling transmission induced by the atom-thick W layers could contribute to the larger magnetoresistance ratio than conventional structures with Ta layers, in addition to the robustness of W layers against high temperature diffusion during annealing. The switching critical current density could be lower than 3.0 MA.cm-2 for devices with a 45 nm radius.