Emergent correlated phases in rhombohedral trilayer graphene induced by proximity spin-orbit and exchange coupling

TL;DR

This paper theoretically explores how proximity-induced spin-orbit and exchange couplings influence the emergence of various correlated phases in rhombohedral trilayer graphene, revealing rich spin-valley phenomena and magneto-correlation effects.

Contribution

It introduces effective models incorporating proximity effects and Coulomb interactions to predict new correlated phases in RTG under different conditions.

Findings

Discovery of spin-valley-coherent phase due to valley-Zeeman coupling

Identification of sensitivity of phases to ferromagnetic layer magnetization orientations

Prediction of rich spectrum of spin-valley resolved instabilities

Abstract

The impact of proximity-induced spin-orbit and exchange coupling on the correlated phase diagram of rhombohedral trilayer graphene (RTG) is investigated theoretically. By employing \emph{ab initio}-fitted effective models of RTG encapsulated by transition metal dichalcogenides (spin-orbit proximity effect) and ferromagnetic Cr$_2$Ge$_2$Te$_6$ (exchange proximity effect), we incorporate the Coulomb interactions within the random-phase approximation to explore potential correlated phases at different displacement field and doping. We find a rich spectrum of spin-valley resolved Stoner and intervalley coherence instabilities induced by the spin-orbit proximity effects, such as the emergence of a \textit{spin-valley-coherent} phase due to the presence of valley-Zeeman coupling. Similarly, proximity exchange removes the phase degeneracies by biasing the spin direction, enabling a magneto-correlation effect -- strong sensitivity of the correlated phases to the relative magnetization orientations (parallel or antiparallel) of the encapsulating ferromagnetic layers.