Electronic transport properties of Co cluster-decorated graphene

TL;DR

This study investigates how cobalt clusters deposited on graphene affect its electronic transport properties, revealing increased scattering, suppression of quantum oscillations, and negative magnetoresistance, explained by weak localization effects.

Contribution

It provides in-situ experimental evidence of cobalt cluster effects on graphene's quantum transport, highlighting the role of disorder and quantum interference.

Findings

Cobalt forms clusters on graphene surface even at low temperatures.

Charge carrier scattering increases with cobalt coverage, suppressing SdH oscillations.

Negative magnetoresistance observed up to 9 T, explained by weak localization.

Abstract

Interactions of magnetic elements with graphene may lead to various electronic states that have potential applications. We report an in-situ experiment in which the quantum transport properties of graphene are measured with increasing cobalt coverage in continuous ultra-high vacuum environment. The results show that e-beam deposited cobalt forms clusters on the surface of graphene, even at low sample temperatures. Scattering of charge carriers by the absorbed cobalt clusters results in the disappearance of the Shubnikov-de Haas (SdH) oscillations and the appearance of negative magnetoresistance (MR) which shows no sign of saturation up to an applied magnetic field of 9 T. We propose that these observations could originate from quantum interference driven by cobalt disorder and can be explained by the weak localization theory.