Spin-split band hybridization in graphene proximitized with $\alpha$-RuCl$_3$ nanosheets

TL;DR

This study investigates the electronic interactions between graphene and antiferromagnetic $ ext{RuCl}_3$ nanosheets, revealing spin-dependent band hybridization, electron transfer, and spin fluctuation effects through low-temperature transport measurements and theoretical calculations.

Contribution

It provides the first detailed experimental and theoretical analysis of graphene's interaction with antiferromagnetic insulators, highlighting spin-split band hybridization and electron transfer mechanisms.

Findings

Evidence of band realignment and electron transfer from graphene to $ ext{RuCl}_3$

Observation of spin-selective hybridization affecting Fermi pockets

Detection of spin fluctuation effects near $ ext{RuCl}_3$'s N{é}el temperature

Abstract

Proximity effects induced in the 2D Dirac material graphene potentially open access to novel and intriguing physical phenomena. Thus far, the coupling between graphene and ferromagnetic insulators has been experimentally established. However, only very little is known about graphene's interaction with antiferromagnetic insulators. Here, we report a low temperature study of the electronic properties of high quality van der Waals heterostructures composed of a single graphene layer proximitized with $\alpha$-RuCl$_3$. The latter is known to become antiferromagnetically ordered below 10 K. Shubnikov de Haas oscillations in the longitudinal resistance together with Hall resistance measurements provide clear evidence for a band realignment that is accompanied by a transfer of electrons originally occupying the graphene's spin degenerate Dirac cones into $\alpha$-RuCl$_3$ band states with in-plane spin polarization. Left behind are holes in two separate Fermi pockets, only the dispersion of one of which is distorted near the Fermi energy due to spin selective hybridization with these spin polarized $\alpha$-RuCl$_3$ band states. This interpretation is supported by our DFT calculations. An unexpected damping of the quantum oscillations as well as a zero field resistance upturn close to the N$\'e$el temperature of $\alpha$-RuCl$_3$ suggests the onset of additional spin scattering due to spin fluctuations in the $\alpha$-RuCl$_3$.