Spin-polarized tunneling through randomly transparent magnetic junctions: Reentrant magnetoresistance approaching the Julliere limit

TL;DR

This paper investigates how disorder affects electron tunneling in magnetic junctions, revealing a reentrant magnetoresistance behavior that approaches the classical Julliere limit at high defect levels.

Contribution

It introduces a theoretical framework to analyze the crossover from momentum-conserving to random tunneling in disordered magnetic junctions, revealing a reentrant magnetoresistance phenomenon.

Findings

Reentrant magnetoresistance observed as defect concentration increases.

Magnetoresistance approaches Julliere's value at high disorder.

Crossover from momentum-conserving to random tunneling regimes.

Abstract

Electron conductance in planar magnetic tunnel junctions with long-range barrier disorder is studied within Glauber-eikonal approximation enabling exact disorder ensemble averaging by means of the Holtsmark-Markov method. This allows us to address a hitherto unexplored regime of the tunneling magnetoresistance effect characterized by the crossover from momentum-conserving to random tunneling as a function of the defect concentration. We demonstrate that such a crossover results in a reentrant magnetoresistance: It goes through a pronounced minimum before reaching disorder- and geometry-independent Julliere's value at high defect concentrations.