Large Rashba Spin-Orbit Coupling and High-Temperature Quantum Anomalous Hall Effect in Re-Intercalated Graphene/CrI$_3$ Heterostructure

TL;DR

This paper proposes a Re-intercalated graphene/CrI3 heterostructure that exhibits large Rashba spin-orbit coupling and a high-temperature quantum anomalous Hall effect, advancing the potential for practical graphene-based electronic devices.

Contribution

It introduces Re-intercalation as a method to induce large Rashba coupling and QAHE in graphene heterostructures, with tunable properties and high-temperature stability.

Findings

Re-intercalation induces Rashba coupling > 40 meV

Large band gaps at valleys K and K' (22.2 and 30.3 meV)

Global band gap over 5.5 meV hosting QAHE

Abstract

In 2010, quantum anomalous Hall effect (QAHE) in graphene was proposed in the presence of Rashba spin-orbit coupling and ferromagnetic exchange field. After a decade's experimental exploration, the anomalous Hall conductance can only reach about 0.25 in the units of $2e^2/h$, which was attributed to the tiny Rashba spin-orbit coupling. Here, we theoretically show that Re-intercalation in graphene/CrI$_3$ heterostructure can not only induce sizeable Rashba spin-orbit coupling ($>$ 40~meV), but also open up large band gaps at valleys $K$ (22.2 meV) and $K' $ (30.3 meV), and a global band gap over 5.5 meV (19.5 meV with random Re distribution) hosting QAHE. A low-energy continuum model is constructed to explain the underlying physical mechanism. We find that Rashba spin-orbit coupling is robust against external stress whereas a tensile strain can increase the global bulk gap. Furthermore, we also show that Re-intercalated graphene with hexagonal boron-nitride can also realize QAHE with bulk gap over 40~meV, indicating the tunability of $5d$-intercalated graphene-based heterostructure. Our finding makes a great leap towards the experimental realization of graphene-based QAHE, and will definitely accelerate the practical application of graphene-based low-power electronics.