Optical Imaging of Flavor Order in Flat Band Graphene

TL;DR

This paper introduces an optical method to detect and image flavor order textures in flat band graphene by measuring exciton responses in adjacent transition metal dichalcogenide layers, offering a new tool for studying many-body physics.

Contribution

It presents a novel optical technique for spatially imaging flavor orders in flat band graphene, complementing electrical measurements and enabling high-throughput analysis.

Findings

Optical exciton response is sensitive to Fermi surface rearrangements.

The method provides spatial maps of flavor order with high throughput.

The technique is compatible with broad temperature and device conditions.

Abstract

Spin and valley flavor polarization plays a central role in the many-body physics of flat band graphene, with fermi surface reconstructions often accompanied by quantized anomalous Hall and superconducting state observed in a variety of experimental systems. Here we describe an optical technique that sensitively and selectively detects flavor textures via the exciton response of a proximal transition metal dichalcogenide layer. Through a systematic study of rhombohedral and rotationally faulted graphene bilayers and trilayers, we show that when the semiconducting dichalcogenide is in direct contact with the graphene, the exciton response is most sensitive to the large momentum rearrangement of the Fermi surface, providing information that is distinct from and complementary to electrical compressibility measurements. The wide-field imaging capability of optical probes allows us to obtain spatial maps of flavor orders with high throughput, and with broad temperature and device compatibility. Our work paves the way for optical probing and imaging of flavor orders in flat band graphene systems.