Nontrivial flat bands and quantum Hall crossovers in square-octagon lattice materials
Fuente:
arXiv
Gespeichert in:
| Hauptverfasser: | , , , |
|---|---|
| Format: | Preprint |
| Veröffentlicht: |
2025
|
| Schlagworte: | |
| Online-Zugang: | |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| _version_ | 1866908659472138240 |
|---|---|
| author | Mukherjee, Amrita Verma, Rahul Srivastava, Pritesh Singh, Bahadur |
| author_facet | Mukherjee, Amrita Verma, Rahul Srivastava, Pritesh Singh, Bahadur |
| contents | Coexistence of nontrivial topology and flat electronic bands in low-energy lattices provides a fertile platform for correlated quantum states. The square-octagon lattice hosts Dirac nodes and flat bands at half-filling, yet the influence of intrinsic spin-orbit coupling (SOC) and staggered magnetic flux on its topological and flat-band properties remains largely unexplored. Here, we examine this lattice using tight-binding models that include SOC and magnetic flux, uncovering a quantum spin Hall phase with spin Chern number $C_s=1$, crossovers to quantum anomalous Hall phases with $C=1$ and $C=2$, and higher-order topological insulator phases carrying quantized quadrupolar corner charges. The initially dispersionless flat bands evolve into quasi-flat, topologically nontrivial bands with uniform quantum geometry and large flatness ratios, conducive to fractional Chern insulator states. We further identify realistic material candidates, including octagraphene, transition-metal dichalcogenides, synthetic $\mathrm{MoSi_2N_4}$, and magnetic $α$-MnO$_2$, as potential candidates for realizing tunable topological phases intertwined with flat-band physics, opening new opportunities for correlated topological matter. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_13349 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Nontrivial flat bands and quantum Hall crossovers in square-octagon lattice materials Mukherjee, Amrita Verma, Rahul Srivastava, Pritesh Singh, Bahadur Mesoscale and Nanoscale Physics Materials Science Coexistence of nontrivial topology and flat electronic bands in low-energy lattices provides a fertile platform for correlated quantum states. The square-octagon lattice hosts Dirac nodes and flat bands at half-filling, yet the influence of intrinsic spin-orbit coupling (SOC) and staggered magnetic flux on its topological and flat-band properties remains largely unexplored. Here, we examine this lattice using tight-binding models that include SOC and magnetic flux, uncovering a quantum spin Hall phase with spin Chern number $C_s=1$, crossovers to quantum anomalous Hall phases with $C=1$ and $C=2$, and higher-order topological insulator phases carrying quantized quadrupolar corner charges. The initially dispersionless flat bands evolve into quasi-flat, topologically nontrivial bands with uniform quantum geometry and large flatness ratios, conducive to fractional Chern insulator states. We further identify realistic material candidates, including octagraphene, transition-metal dichalcogenides, synthetic $\mathrm{MoSi_2N_4}$, and magnetic $α$-MnO$_2$, as potential candidates for realizing tunable topological phases intertwined with flat-band physics, opening new opportunities for correlated topological matter. |
| title | Nontrivial flat bands and quantum Hall crossovers in square-octagon lattice materials |
| topic | Mesoscale and Nanoscale Physics Materials Science |
| url | https://arxiv.org/abs/2511.13349 |