Conformational change-modulated spin transport at the single-molecule level in carbon systems --Invited for the Third Carbon Special Topic

TL;DR

This study demonstrates how conformational changes in graphene nanoflakes can modulate spin transport at the single-molecule level, enabling spin switching and filtering without ferromagnetic contacts, with potential applications in spintronics.

Contribution

It introduces a novel mechanism for controlling spin transport via molecular conformation, using first-principles calculations to show dual-spin filtering in carbon-based systems.

Findings

Spin polarization can be switched by rotating functional groups.

Transition between spin-up and spin-down states acts as a dual-spin filter.

The effect is robust across different nanoflake sizes and electrode materials.

Abstract

Controlling the spin transport at the single-molecule level, especially without the use of ferromagnetic contacts, becomes a focus of research in spintronics. Inspired by the progress on atomic-level molecular synthesis, through first-principles calculations, we investigate the spin-dependent electronic transport of graphene nanoflakes with side-bonded functional groups, contacted by atomic carbon chain electrodes. It is found that, by rotating the functional group, the spin polarization of the transmission at the Fermi level could be switched between completely polarized and unpolarized states. Moreover, the transition between spin-up and spin-down polarized states can also be achieved, operating as a dual-spin filter. Further analysis shows that, it is the spin-dependent shift of density of states, caused by the rotation, that triggers the shift of transmission peaks, and then results in the variation of spin polarization. Such a feature is found to be robust to the of the nanoflake and the electrode material, showing great application potential. Those findings may throw light on the development of spintronic devices.