Imaging de Haas-van Alphen quantum oscillations and milli-Tesla pseudomagnetic fields

Abstract

A unique attribute of atomically thin quantum materials is the in-situ tunability of their electronic band structure by externally controllable parameters like electrostatic doping, electric field, strain, electron interactions, and displacement or twisting of atomic layers. This unparalleled control of the electronic bands has led to the discovery of a plethora of exotic emergent phenomena. But despite its key role, there is currently no versatile method for mapping the local band structure in advanced 2D materials devices in which the active layer is commonly embedded in various insulating layers and metallic gates. Utilizing a scanning superconducting quantum interference device, we image the de Haas-van Alphen quantum oscillations in a model system, the Bernal-stacked trilayer graphene with dual gates, which displays multiple highly-tunable bands. By resolving thermodynamic quantum oscillations spanning over 100 Landau levels in low magnetic fields, we reconstruct the band structure and its controllable evolution with the displacement field with unprecedented precision and spatial resolution of 150 nm. Moreover, by developing Landau level interferometry, we reveal shear-strain-induced pseudomagnetic fields and map their spatial dependence. In contrast to artificially-induced large strain, which leads to pseudomagnetic fields of hundreds of Tesla, we detect naturally occurring pseudomagnetic fields as low as 1 mT corresponding to graphene twisting by just 1 millidegree over one μm distance, two orders of magnitude lower than the typical angle disorder in high-quality twisted bilayer graphene devices. This ability to resolve the local band structure and strain on the nanoscale opens the door to the characterization and utilization of tunable band engineering in practical van der Waals devices.

Nature (2023)

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Cited by in corpus (8)

• A Microscopic Perspective on Moiré Materials
• Imaging Coulomb interactions and migrating Dirac cones in twisted graphene by local quantum oscillations
• Room temperature relaxometry of single nitrogen-vacancy centers in proximity to $\alpha$-RuCl${}_3$ nanoflakes
• Capacitive scheme to detect the topological magnetoelectric effect
• Tunable Band Inversion in Trilayer Graphene
• Real-space chirality from crystalline topological defects in the Kitaev spin liquid
• Scalable tight-binding model for strained graphene
• Mode-Resolved Multiband Ballistic Transport and Conductance Thresholds in Bilayer Graphene Junctions