Band touching from real space topology in frustrated hopping models(Topological Aspects of Solid State Physics)
By D. Bergman, Congjun Wu, L. Balents. 2008
270 citations recorded by the source corpus.
We study ``frustrated'' hopping models, in which at least one energy band, at the maximum or minimum of the spectrum, is dispersionless. The states of the flat band(s) can be represented in a basis which is fully localized, having support on a vanishing fraction of the system in the thermodynamic limit. In the majority of examples, a dispersive band touches the flat band(s) at a number of discrete points in momentum space. We demonstrate that this band touching is related to states which exhibit non-trivial topology in real space. Specifically, these states have support on one-dimensional loops which wind around the entire system (with periodic boundary conditions). A counting argument is given that determines, in each case, whether there is band touching or not, in precise correspondence to the result of straightforward diagonalization. When they are present, the topological structure protects the band touchings in the sense that they can only be removed by perturbations which {\sl also} split the degeneracy of the flat band.
Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics
View Paper: https://www.semanticscholar.org/paper/e123ed7efd1d0082481259600f5cda75af69e9b5
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In Atomic and Molecular Physics, and Optics
In Condensed Matter Physics
Citations in the corpus
- Artificial flat band systems: from lattice models to experiments (2018, background): “[38] showed that the set of CLS in two dimensions can turn linearly dependent precisely when the flat band touches a non-flat (dispersive) band at one or more points in the Brillouin zone.”
- Flat bands, strange metals and the Kondo effect (2023, unknown): “3c), in which the temperature exponent 1 spans more than three orders of magnitude in temperature 49 ; the kagome metal Ni 3 In (ref.”