Absence of a transport signature of spin-orbit coupling in graphene with indium adatoms

TL;DR

This study investigates whether indium adatoms can enhance spin-orbit coupling in graphene by conducting various transport measurements, but finds no evidence of such enhancement, challenging previous expectations.

Contribution

The paper provides experimental evidence that indium adatoms do not induce detectable spin-orbit coupling in graphene, contrary to prior theoretical predictions.

Findings

No weak localization magnetoresistance signature of spin-orbit coupling

Absence of quantum spin Hall effect signals

No non-local spin Hall effect observed

Abstract

Enhancement of the spin-orbit coupling in graphene may lead to various topological phenomena and also find applications in spintronics. Adatom absorption has been proposed as an effective way to achieve the goal. In particular, great hope has been held for indium in strengthening the spin-orbit coupling and realizing the quantum spin Hall effect. To search for evidence of the spin-orbit coupling in graphene absorbed with indium adatoms, we carry out extensive transport measurements, i.e., weak localization magnetoresistance, quantum Hall effect and non-local spin Hall effect. No signature of the spin-orbit coupling is found. Possible explanations are discussed.