Magnetization reversal in sub-100nm magnetic tunnel junctions with ultrathin MgO barrier biased along hard axis

TL;DR

This study demonstrates low-current magnetization switching in sub-100nm magnetic tunnel junctions with ultrathin MgO barriers, revealing the role of localized barrier reductions and pseudo pinholes in switching behavior.

Contribution

It provides new insights into current-induced magnetization switching mechanisms in ultrathin MgO barriers, supported by experimental noise analysis and micromagnetic simulations.

Findings

Magnetization switching occurs at low current densities (~4×10^6 A/cm^2).

Localized barrier reductions influence switching behavior.

Micromagnetic simulations match experimental observations.

Abstract

We report on room temperature magnetoresistance and low frequency noise in sub-100nm elliptic CoFeB/MgO/CoFeB magnetic tunnel junctions with ultrathin (0.9nm) barriers. For magnetic fields applied along the hard axis, we observe current induced magnetization switching between the antiparallel and parallel alignments at DC current densities as low as 4*106A/cm2. We attribute the low value of the critical current to the influence of localized reductions in the tunnel barrier, which affects the current distribution. The analysis of random telegraph noise, which appears in the field interval near a magnetization switch, provides an estimate to the dimension of the pseudo pinholes that trigger the magnetization switching via local spin torque. Micromagnetic simulations qualitatively and quantitatively reproduce the main experimental observations.