Spin Relaxation in Graphene with self-assembled Cobalt Porphyrin Molecules

TL;DR

This study investigates how self-assembled cobalt-porphyrin molecules on graphene influence spin relaxation, revealing a slight decrease in relaxation time and highlighting the role of molecular magnetic moments in spin transport.

Contribution

It provides new insights into the impact of organic magnetic molecules on graphene's spin relaxation mechanisms through experimental measurements.

Findings

Slight decrease in spin relaxation time ({ au}s) with molecular functionalization.

Enhanced spin-flip scattering due to molecular magnetic moments.

Masking of effects in low mobility samples due to dominant EY relaxation.

Abstract

In graphene spintronics, interaction of localized magnetic moments with the electron spins paves a new way to explore the underlying spin relaxation mechanism. A self-assembled layer of organic cobalt-porphyrin (CoPP) molecules on graphene provides a desired platform for such studies via the magnetic moments of porphyrin-bound cobalt atoms. In this work a study of spin transport properties of graphene spin-valve devices functionalized with such CoPP molecules as a function of temperature via non-local spin-valve and Hanle spin precession measurements is reported. For the functionalized (molecular) devices, we observe a slight decrease in the spin relaxation time ({\tau}s), which could be an indication of enhanced spin-flip scattering of the electron spins in graphene in the presence of the molecular magnetic moments. The effect of the molecular layer is masked for low quality samples (low mobility), possibly due to dominance of Elliot-Yafet (EY) type spin relaxation mechanisms.