Quantum-Dot Assisted Spectroscopy of Degeneracy-Lifted Landau Levels in Graphene

Abstract

Energy spectroscopy of strongly interacting phases requires probes which minimize screening while retaining spectral resolution and local sensitivity. Here we demonstrate that such probes can be realized using atomic sized quantum dots bound to defects in hexagonal Boron Nitride tunnel barriers, placed at nanometric distance from graphene. With dot energies capacitively tuned by a planar graphite electrode, dot-assisted tunneling becomes highly sensitive to the graphene excitation spectrum. The spectra track the onset of degeneracy lifting with magnetic field at the ground state, and at unoccupied exited states, revealing symmetry-broken gaps which develop steeply with magnetic field - corresponding to Landé $g$ factors as high as 160. Measured up to $B=33$ T, spectra exhibit a primary energy split between spin-polarized excited states, and a secondary spin-dependent valley-split. Our results show that defect dots probe the spectra while minimizing local screening, and are thus exceptionally sensitive to interacting states.

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Cited by in corpus (6)

• Spectroscopy of $NbS{e}_2$ using Energy-Tunable Defect-Embedded Quantum Dots
• Tunneling Spectroscopy of Two-Dimensional Materials Based on Via Contacts
• Imaging the Sub-Moiré Potential Landscape using an Atomic Single Electron Transistor
• A magnetically-induced Coulomb gap in graphene due to electron-electron interactions
• Kondo Effect in Defect-bound Quantum Dots Coupled to NbSe${}_2$
• Energy spectra of graphene quantum dots induced between Landau levels