Engineering insulator-metal transition in a class of decorated aperiodic lattices: a quantum dynamical study

TL;DR

This study demonstrates that specific correlations in decorated quasiperiodic and random lattices can induce a complete insulator-metal transition in wave packet dynamics, controllable via system parameters and external magnetic flux.

Contribution

It reveals a novel mechanism for inducing insulator-metal transitions through correlated disorder in aperiodic lattices, analyzed via quantum dynamical methods.

Findings

Correlations cause complete wave packet delocalization independent of energy.

Parameter tuning induces insulator-metal transition across the energy spectrum.

External magnetic flux can control the transition.

Abstract

We investigate the quantum dynamics of wave packets in a class of decorated lattices, both quasiperiodic and random, where a nominal quasi-one dimensionality is introduced at local levels, bringing in a deterministic or even random variations in the distribution of the coordination number throughout the system. We show that certain correlations in the numerical values of the system Hamiltonian can cause a drastic change in the dynamical evolution of the wave packet, revealing a complete delocalization, independent of the energy of the travelling particle, even in the absence of any translational invariance. We use an exact decimation of a selected subset of the degrees of freedom, and an analysis of the commutation of the $2 \times 2$ transfer matrices on a renormalized version of the parent systems within a tight binding framework. An in-depth analysis of the mean square displacement, temporal autocorrelation function and the inverse participation ratio establishes the gross change in the behaviour of the wave packet dynamics. The consequence is the occurrence of a parameter-driven insulator-metal transition over the full (or a major) range of the energy spectrum in each case. In certain cases, inclusion of an external magnetic flux enables us to control the transition. The observation is general, and, to our mind, can inspire experiments involving photonics or matter wave localization.