Dynamic properties of quantum spin chains: Simple route to complex behavior

TL;DR

This paper investigates how inhomogeneities like periodic and random variations in spin chain interactions affect their dynamic properties, revealing that such effects can be understood through transformations linking them to uniform chains.

Contribution

It provides a method to compute dynamic structure factors of inhomogeneous spin chains by transforming them into uniform chains, simplifying analysis of complex disordered systems.

Findings

Inhomogeneities can be eliminated via transformation, linking inhomogeneous and uniform chains.

Dynamic structure factors are affected by regular and random inhomogeneities.

Analytical and numerical results show the impact of disorder on quantum spin dynamics.

Abstract

We examine dynamic structure factors of spin-1/2 chains with nearest-neighbor interactions of XX and Dzyaloshinskii-Moriya type, and with periodic and random changes in the sign of these interactions. This special kind of inhomogeneity can be eliminated from the Hamiltonian by suitable transformation of the spin variables. As a result, the dynamic structure factors of periodic or random chains can be computed from those of the uniform chains. Using the exact analytical and precise numerical results available for the uniform systems we illustrate the effects of regular alternation or random disorder on dynamic structure factors of quantum spin chains.