Electronic transport properties of Ir-decorated graphene

TL;DR

This study investigates how iridium decoration affects graphene's electrical properties, revealing cluster formation and mobility changes, but no evidence of a spin-orbit coupling induced energy gap.

Contribution

It provides experimental insights into Ir cluster formation and transport properties in graphene, challenging the expectation of a topological gap.

Findings

Ir clusters of ~100 atoms form at low temperature

Annealing increases cluster size and mobility

No energy gap observed despite Ir decoration

Abstract

Graphene decorated with 5d transitional metal atoms is predicted to exhibit many intriguing properties; for example iridium adatoms are proposed to induce a substantial topological gap in graphene. We extensively investigated the conductivity of single-layer graphene decorated with iridium deposited in ultra-high vacuum at low temperature (7 K) as a function of Ir concentration, carrier density, temperature, and annealing conditions. Our results are consistent with the formation of Ir clusters of ~100 atoms at low temperature, with each cluster donating a single electronic charge to graphene. Annealing graphene increases the cluster size, reducing the doping and increasing the mobility. We do not observe any sign of an energy gap induced by spin-orbit coupling, possibly due to the clustering of Ir.