Edge-state influence on high-order harmonic generation in topological nanoribbons

Abstract

The high-order harmonic generation in finite topological nanoribbons is investigated using a tight-binding approximation. The narrow, two-dimensional ribbons consist of hexagonal structures. A topological phase transition is defined by a sudden change of the topological invariant. In the bulk, this kind of phase transition might occur if an existing band gap closes and reopens again. Through the bulk-boundary correspondence, this is related to the emergence of topologically protected edge states in the respective finite systems. For the finite ribbons studied in this work, the variation of the tight-binding parameters leads to the emergence of two edge states after the closing of the band gap. The energies of those edge states as functions of the tight-binding parameters display crossings and avoided crossings, which influence the high-harmonic spectra. Graphic Abstract

Topological edge-state contributions to high-order harmonic generation in finite flakes

“…The theoretical description of the system is similar to our previous works [24,34,37]. In particular, the method to calculate high-harmonic spectra is the same.…”

“…Often, HHG is discussed in terms of the bulk properties of the system. However, the edges may have a significant influence on the emission of light as well [19][20][21][22][23][24]. In particular, topological insulators might be of interest, which are insulating in their interior (i.e., their bulk) but allow for current flow along the edges (in 2D materials) or surfaces (in 3D).…”

“…Harmonic generation in Haldanite has been studied for the bulk [32,33] and finite ribbons [24,34]. Further studies were devoted to HHG in three-dimensional topological insulators.…”

Quantum aspects of attoscience

“…See, for instance, the discussion about macroscopic coherence in ATI brought up in this editorial and in the perspective article [ 3 ]. This issue also features articles on HHG in topological nanoribbons [ 10 ], and strong-field ionization [ 11 ] in nanoparticles. In [ 10 ], Jürß and Bauer investigate the influence of edge-states in topological nanoribbons on HHG.…”

“…This issue also features articles on HHG in topological nanoribbons [ 10 ], and strong-field ionization [ 11 ] in nanoparticles. In [ 10 ], Jürß and Bauer investigate the influence of edge-states in topological nanoribbons on HHG. They show that the crossings and avoided crossings that occur in the energy of these states strongly affect the HHG properties.…”