Floquet topological semimetal phases of an extended kicked Harper model

TL;DR

This paper explores Floquet topological semimetal phases in an extended kicked Harper model, revealing new Weyl points and line nodes, and demonstrating edge states and adiabatic pumping schemes to characterize their topological properties.

Contribution

It introduces a generalized kicked Harper model with artificial dimensions, uncovering new topological features like Weyl points and line nodes in Floquet systems.

Findings

Emergence of Weyl points at quasienergies 0 and π with increased parameters

Observation of Fermi arc-like edge states in the model

Design of an adiabatic pumping scheme to reveal Weyl point chirality and Berry phase

Abstract

Recent discoveries on topological characterization of gapless systems have attracted interest in both theoretical studies and experimental realizations. Examples of such gapless topological phases are Weyl semimetals, which exhibit 3D Dirac cones (Weyl points), and nodal line semimetals, which are characterized by line nodes (two bands touching along a line). Inspired by our previous discoveries that the kicked Harper model exhibits many fascinating features of Floquet topological phases, in this manuscript we consider a generalization of the model, where two additional periodic system parameters are introduced into the Hamiltonian to serve as artificial dimensions, so as to simulate a 3D system. We observe that by increasing the hopping strength and the kicking strength of the system, many new band touching points at Floquet quasienergies $0$ and $\pi$ will start to appear. Some of them are Weyl points, while the others form line nodes in the parameter space. By taking open boundary conditions along the physical dimension, edge states analogues to Fermi arcs in static Weyl semimetal systems are observed. Finally, by designing an adiabatic pumping scheme, the chirality of the Weyl points and the $\pi$ Berry phase around line nodes can be manifested.