Interplay of symmetry-conserved tunneling, interfacial oxidation and perpendicular magnetic anisotropy in CoFeB/MgO-based junctions

TL;DR

This study investigates how interfacial oxidation, symmetry-conserved tunneling, and thermal processes influence the magnetic and electronic properties of CoFeB/MgO junctions, revealing ways to enhance their performance.

Contribution

It demonstrates the impact of interfacial oxidation and thermal stability on tunneling and magnetic properties, providing strategies to improve junction performance.

Findings

Symmetry-conserved tunneling depends on MgO adatom energy during sputtering.

Two failure modes affect magnetoresistance: decay of magnetic anisotropy and destruction of tunneling channels.

Controlling oxidation and layer selection enhances magnetic anisotropy and tunneling magnetoresistance.

Abstract

The interfacial oxidation level and thermodynamic properties of the MgO-based perpendicular magnetic tunneling junctions are investigated. The symmetry-conserved tunneling effect depends sensitively on the MgO adatom energy during the RF sputtering, as well as the thermal stability of the structure during the post-growth thermal annealing. Two different failure modes of the magnetoresistance are highlighted, involving with the decay of perpendicular magnetic anisotropy and destruction of coherent tunneling channels, respectively. Through the careful control of interfacial oxidation level and proper selection of the heavy metal layers, both perpendicular magnetic anisotropy and tunneling magnetoresistance of the junctions can be increased.