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Flat Bands

All articles tagged with #flat bands

Direct imaging uncovers dual light and heavy electron bands in magic-angle graphene
science20 days ago

Direct imaging uncovers dual light and heavy electron bands in magic-angle graphene

Using the quantum twisting microscope, researchers map the interacting energy bands of magic-angle twisted bilayer graphene (MATBG). Away from the magic angle the bands follow single-particle predictions, but at the magic angle interactions reshape them into largely flat, gapped bands across most of momentum space, with dispersive, light-electron states near Γ. Upon doping, charge transfers between light (c-like) and heavy (f-like) states drive bandwidth renormalization, Mott-like cascades, and Dirac revivals, while an unexplained ~15 meV excitation hints at an additional degree of freedom. The work resolves MATBG’s long-standing duality and showcases the quantum twisting microscope as a powerful tool for high-resolution quantum-material spectroscopy.

Switchable quantum material promises real-time control for future chips
innovation2 months ago

Switchable quantum material promises real-time control for future chips

US researchers identify a nickel sulfide compound, KxNi4S2, that reversibly switches between Dirac-cone and flat-band quantum states by electrically tuning potassium content, enabling real-time control of electron speed and flow. Demonstrated at Argonne's Center for Nanoscale Materials and Advanced Photon Source, the work could simplify device design and boost future chip and sensor performance; the study was published in Matter.