Low-frequency noise and tunnelling magnetoresistance in Fe(110)/MgO(111)/Fe(110) epitaxial magnetic tunnel junctions

TL;DR

This study investigates the low-frequency noise and tunnelling magnetoresistance in high-quality epitaxial Fe/MgO/Fe magnetic tunnel junctions, revealing a correlation between magnetic states, barrier defects, and noise characteristics.

Contribution

It provides detailed measurements of TMR, IV characteristics, and noise in epitaxial Fe/MgO/Fe MTJs, highlighting the impact of magnetic configuration and defects on noise behavior.

Findings

High-quality epitaxial growth confirmed by consistent barrier parameters.

Large variation in noise power, anticorrelated with TMR.

Enhanced noise in antiparallel state for larger junctions.

Abstract

We report on tunnelling magnetoresistance (TMR), current-voltage (IV) characteristics and low frequency noise in epitaxially grown Fe(110)/MgO(111)/Fe(110) magnetic tunnel junctions (MTJs) with dimensions from 2x2 to 20x20 um2. The evaluated MgO energy barrier (0.50+/-0.08 eV), the barrier width (13.1+/-0.5 angstrom) as well as the resistance times area product (7+/-1 Mohmsum2) show relatively small variation, confirming a high quality epitaxy and uniformity of all MTJs studied. The noise power, though exhibiting large variation, was observed to be roughly anticorrelated with the TMR. Surprisingly, for the largest junctions we observed a strong enhancement of the normalized low-frequency noise in the antiparallel magnetic configuration. This behaviour could be related to an interplay between the magnetic state and the local barrier defects structure of the epitaxial MTJs