Inelastic transport in molecular spin valves

TL;DR

This paper investigates how inelastic scattering affects electron transport in molecular spin valves and H$_2$ molecules, revealing that inelastic effects decrease conductance and spin-polarization, impacting device performance.

Contribution

It introduces a multi-channel method to analyze inelastic effects in nanoscale devices, combining a tight-binding Hamiltonian with Pauli exclusion, and applies it to molecular and spin-valve systems.

Findings

Inelastic backscattering causes conductance drops at certain biases.

Inelastic scattering reduces spin-polarization and magnetoresistance.

The Fermi level position influences spin-current and magnetoresistance.

Abstract

We present a study of the effects of inelastic scattering on the transport properties of various nanoscale devices, namely H$_2$ molecules sandwiched between Pt contacts, and a spin-valve made by an organic molecule attached to model half-metal ferromagnetic current/voltage probes. In both cases we use a tight-binding Su-Schrieffer-Heeger Hamiltonian and the inelastic effects are treated with a multi-channel method, including Pauli exclusion principle. In the case of the H$_2$ molecule, we find that inelastic backscattering is responsible for the drop of the differential conductance at biases larger than the excitation energy of the lower of the molecular phonon modes. In the case of the spin-valve, we investigate the different spin-currents and the magnetoresistance as a function of the position of the Fermi level with respect to the spin-polarized band edges. In general inelastic scattering reduces the spin-polarization of the current and consequently the magnetoresistance.