Topological phase transition and its stability against an applied magnetic field in a class of low dimensional decorated lattices

TL;DR

This paper analytically investigates topological phase transitions in decorated lattices, demonstrating the robustness of topological invariants and edge states against magnetic fields and identifying conditions for phase transitions.

Contribution

It provides exact analytical results on topological phase transitions and edge state protection in decorated lattices under magnetic fields, extending understanding of topological robustness.

Findings

Topological invariants remain quantized despite magnetic flux.

Edge localized modes appear at gap-closing energies.

Topological phase transition conditions depend on hopping parameters.

Abstract

The possibility of topological phase transition with or without a magnetic flux trapped in the cells of a class of decorated lattices is explored in details.Using a tight binding Hamiltonian and a real space decimation scheme we analytically obtain the non-dispersive and dispersive energy bands, and exactly locate the eigenvalues at which energy gaps close.We find that despite the local breaking of the time reversal symmetry, as a magnetic field is turned on, the topological invariant exhibits quantization, and a clear appearance of edge localized modes is observed exactly at the gap-closing energy eigenvalues in the topologically non-trivial insulating phase.The bulk boundary correspondence is obeyed. The protection of the edge states by a chiral symmetry is confirmed for both the presence and absence of magnetic flux. Our studies have been extended to other kinds of decorated lattices where topological phase transition is possible only above a threshold value of the hopping integral describing these lattice. Our results are analytically exact.