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Topological heavy fermions in magnetic field
Keshav Singh1,2, Aaron Chew3, Jonah Herzog-Arbeitman3
1National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA.
Nature Communications
|June 19, 2024
Summary
We generalized the topological heavy fermion model (THFM) to include magnetic fields, revealing the interacting Hofstadter spectra in twisted bilayer graphene. Our method correctly reproduces the total Chern number, offering insights into Landau quantization.
Area of Science:
- Condensed Matter Physics
- Quantum Materials
- Topological Materials
Background:
- The topological heavy fermion model (THFM) explains low-energy electronic behavior in magic angle twisted bilayer graphene.
- A magnetic field generalization of THFM is needed to understand Landau quantization.
Purpose of the Study:
- To systematically derive and solve the THFM in the presence of a magnetic field.
- To obtain the interacting Hofstadter spectra for single-particle charged excitations.
Main Methods:
- Generalized the THFM to include a magnetic field (B).
- Projected light and heavy fermions onto irreducible representations of the magnetic translation group.
- Solved the resulting model to obtain the interacting Hofstadter spectra.
Main Results:
- Successfully derived the THFM in a magnetic field.
- Obtained the interacting Hofstadter spectra for charged excitations.
- The novel projection method correctly reproduces the total Chern number, unlike naive minimal substitution.
Conclusions:
- The generalized THFM provides an intuitive understanding of strongly interacting Hofstadter bands in twisted bilayer graphene.
- The developed method accurately captures Landau quantization effects.
- This work lays the foundation for further theoretical and experimental investigations of topological phenomena in twisted bilayer graphene under magnetic fields.
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