Hierarchical description of phonon dynamics on finite Fibonacci superlattices

Abstract

We study the phonon dynamics of Fibonacci heterostructures where two kinds of order (namely, periodic and quasiperiodic) coexist in the same sample at different length scales. We derive analytical expressions describing the dispersion relation of finite Fibonacci superlattices in terms of nested Chebyshev polynomials of the first and second kinds. In this way, we introduce a unified description of the phonon dynamics of Fibonacci heterostructures, able to exploit their characteristic hierarchical structure in a natural way.