Terahertz Landau level spectroscopy of Dirac fermions in millimeter-scale twisted bilayer graphene

Journal Article · Wed Jan 01 00:00:00 EST 2025 · Physical Review B

DOI:https://doi.org/10.48550/arXiv.2504.20156· OSTI ID:2999114

Mead, Benjamin F.; Talkington, Spenser; Chen, An-Hsi; Mallick, Debarghya; Chu, Zhaodong; Han, Xingyue; Yang, Seong-Jun; Kim, Cheol-Joo; Brahlek, Matthew; Mele, Eugene J.; Wu, Liang

Exotic electronic physics including correlated insulating states and fractional Chern insulators have been observed in twisted bilayer graphene in a magnetic field when the Fermi velocity vanishes, however a question remains as to the stability of these states which is controlled by the gap to the first excited state. Free-space terahertz magneto-optics can directly probe the gap to charge excitations which bounds the stability of electronic states, but this measurement has thus-far been inaccessible due to the micron size of twisted bilayer graphene samples, while the wavelength of terahertz light is up to a millimeter. Here we leverage advances in fabrication to create twisted bilayer graphene samples over 5 mm x 5 mm in size with a uniform twist angle and study the magnetic field dependence of the cyclotron resonance by a complex Faraday rotation experiment in p-doped large angle twisted bilayer graphene. These measurements directly probe charge excitations in inter-Landau level transitions and determine the Fermi velocity as a function of twist angle.

• Research Organization: arXiv
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
• Grant/Contract Number: FG02-84ER45118
• OSTI ID: 2999114
• Journal Information: Physical Review B, Journal Name: Physical Review B
• Publisher: American Physical Society One Physics Ellipse College Park MD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
77 NANOSCIENCE AND NANOTECHNOLOGY
FOS: Physical sciences
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Quantum Physics (quant-ph)