Peculiarities of Spin Polarization Inversion at a Thiophene/Cobalt Interface

TL;DR

This study uses ab-initio calculations to explore how sulfur in thiophene causes unique, spatially dependent spin polarization inversion at the interface with cobalt, affecting spin transport properties.

Contribution

It reveals the role of sulfur-induced symmetry reduction in causing spatially varying spin polarization at the thiophene/cobalt interface.

Findings

Carbon atoms far from sulfur have opposite spin polarization to cobalt.

Carbon atoms bonded to sulfur share the same polarization as cobalt.

The spin polarization pattern significantly influences spin transport.

Abstract

We perform ab-initio calculations to investigate the spin polarization at the interface between a thiophene molecule and cobalt substrate. We find that the reduced symmetry in the presence of a sulfur atom (in the thiophene molecule) leads to a strong spatial dependence of the spin polarization of the molecule: The two carbon atoms far from the sulfur acquire a polarization opposite to that of the substrate, while the carbon atoms bonded directly to sulfur possess the same polarization as the substrate. We determine the origin of this peculiar spin interface property as well as its impact on the spin transport.