Negative Magnetoresistance and Spin Filtering of Spin-Coupled Diiron-Oxo Clusters

TL;DR

This study investigates spin-dependent electron transport in a diiron-oxo cluster, revealing tunable colossal magnetoresistance and near-perfect spin filtering, with potential applications in spintronic devices.

Contribution

It demonstrates how bias voltage and anchoring methods can control magnetoresistance sign and magnitude, and shows the cluster's exceptional spin filtering capabilities.

Findings

Colossal magnetoresistance ratio up to 6000% with hydrogen anchoring.

Negative magnetoresistance induced by low bias and sulfur anchoring.

Near-perfect spin filtering for parallel magnetic moments.

Abstract

Spin dependent transport has been investigated for an {\it open shell singlet} diiron-oxo cluster. Currents and magnetoresistances have been studied, as a function of spin state, within the non-equilibrium Green's function approach. The applied bias can be used for tuning the sign of the observed magnetoresistance. A colossal magnetoresistance ratio has been determined, on the order of to 6000$%$, for hydrogen anchoring. Applied biases lower than 0.3 V, in conjunction with sulfur anchoring, induce a negative magnetoresistance due to lowering of the anchor-scatterer tunneling barrier. In addition, the diiron-oxo cluster displays nearly perfect spin filtering for parallel alignment of the iron magnetic moments due to energetic proximity, relative to the Fermi level, of its highest occupied molecular orbitals.