Topological states on fractal lattices

S Pai, A Prem - Physical Review B, 2019 - APS
Physical Review B, 2019APS
We investigate the fate of topological states on fractal lattices. Focusing on a spinless chiral
p-wave paired superconductor, we find that this model supports two qualitatively distinct
phases when defined on a Sierpinski gasket. While the trivial phase is characterized by a
self-similar spectrum with infinitely many gaps and extended eigenstates, the “topological”
phase has a gapless spectrum and hosts chiral states propagating along edges of the
graph. Besides employing theoretical probes such as the real-space Chern number, inverse …
We investigate the fate of topological states on fractal lattices. Focusing on a spinless chiral -wave paired superconductor, we find that this model supports two qualitatively distinct phases when defined on a Sierpinski gasket. While the trivial phase is characterized by a self-similar spectrum with infinitely many gaps and extended eigenstates, the “topological” phase has a gapless spectrum and hosts chiral states propagating along edges of the graph. Besides employing theoretical probes such as the real-space Chern number, inverse participation ratio, and energy-level statistics in the presence of disorder, we develop a simple physical picture capturing the essential features of the model on the gasket. Extending this picture to other fractal lattices and topological states, we show that the state admits a gapped topological phase on the Sierpinski carpet and that a higher-order topological insulator placed on this lattice hosts gapless modes localized on corners.
American Physical Society
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