Symmetry Dependent Scattering by Minority Interface Resonance States in Single-crystal Magnetic Tunnel Junctions

TL;DR

This study investigates how symmetry-dependent minority interface resonance states affect electron tunneling in epitaxial Fe/MgO/Fe magnetic tunnel junctions, revealing how doping alters these states and conductance.

Contribution

It demonstrates the impact of carbon doping on the symmetry and spectral composition of interface resonance states in magnetic tunnel junctions.

Findings

IRS in carbon-free samples is dominated by delta5 symmetry.

Carbon doping shifts IRS spectral composition to delta1 symmetry.

Doping influences conductance by modifying IRS symmetry contributions.

Abstract

Symmetry dependent scattering effect by minority interface resonance states (IRS) has been evidenced in full-epitaxial Fe/MgO/Fe magnetic tunnel junctions (MTJs). Two types of samples with and without carbon doped bottom Fe/MgO interface were fabricated to represent two different types of IRS in the minority channel in the vicinity of the Fermi level. By analysis of the first- principles calculated local density of states (LDOS) and the temperature dependence of conductance in parallel configuration at low bias, we show that the IRS in the carbon free sample is dominated by the delta5 symmetry. This has a major contribution on the majority deltai to delta5 channel scattering and explains the enhancement of the delta5 conductance in the parallel configuration at low temperature. Furthermore, the spectral composition of the IRS in the carbon doped interface is found to be dominated by the delta1 symmetry, which is responsible for the suppression of delta5 channel in the parallel conductance.