Magnetoresistance of the double-tunnel-junction Coulomb Blockade with magnetic metals

TL;DR

This paper investigates the magnetoresistance behavior in double-tunnel-junctions with magnetic metals within the Coulomb Blockade regime, revealing voltage-dependent spikes and variations in junction magnetoresistance.

Contribution

It provides the first detailed analysis of JMR and DJMR in Coulomb Blockade double junctions, highlighting voltage-dependent phenomena and the conditions affecting their signs and magnitudes.

Findings

JMR is positive across studied conditions.

DJMR can be positive or negative depending on voltage.

Voltage variation of DJMR exceeds that of JMR.

Abstract

We have studied the Junction Magnetoresistance (JMR) and the Differential junction magnetoresistance (DJMR) for double tunnel junctions with magnetic metals in the Coulomb Blockade regime. Spikes are seen in both the JMR and the DJMR vs. voltage curves. They occur at those places where the current increases by a step. In all cases the large bias limit can be obtained by adding the resistances of each of the junctions in series. The JMR is positive in all the cases we studied, whereas the DJMR can be positive or negative as a function of the voltage. Moreover, the relative variation of the DJMR as a function of the voltage is larger than the variation of the JMR with the voltage.