PIRSA:19070086 Scientific Series Condensed Matter

DOI10.48660/19070086

Series: Quantum Matter

Cho, G.Y. (2019). Stable Flat Bands, Topology, and Superconductivity of Magic Honeycomb Network. Perimeter Institute. https://pirsa.org/19070086

Cho, Gil Young. Stable Flat Bands, Topology, and Superconductivity of Magic Honeycomb Network. Perimeter Institute, Jul. 30, 2019, https://pirsa.org/19070086 

@misc{ pirsa_PIRSA:19070086,
  doi = {10.48660/19070086},
  url = {https://pirsa.org/19070086},
  author = {Cho, Gil Young},
  keywords = {Condensed Matter},
  language = {en},
  title = {Stable Flat Bands, Topology, and Superconductivity of Magic Honeycomb Network},
  publisher = {Perimeter Institute},
  year = {2019},
  month = {jul},
  note = {PIRSA:19070086 see, \url{https://pirsa.org}}
}

Abstract

We uncover a rich phenomenology of the self-organized honeycomb network superstructure of one-dimensional metals in a nearly-commensurate charge-density wave 1T-TaS${}_2$, which may play a significant role in understanding global topology of phase diagrams and superconductivity. The key observation is that the emergent honeycomb network magically supports a cascade of flat bands, whose unusual stability we thoroughly investigate. Furthermore, by combining the weak-coupling mean-field and strong-coupling approaches, we argue that the superconductivity will be strongly enhanced in the network. This provides a natural cooperative mechanism of the charge order and superconductivity, which coexist side-by-side in the 1T-TaS${}_2$. Not only explaining the superconductivity, we show that abundant topological band structures including several symmetry-protected band crossings and corner states, which are closely related to that of the higher-order topology, appear. The results reported here can be generically applicable to various other systems with similar network superstructures.

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