High temperature correlation functions: universality, extraction of exchange interactions, divergent correlation lengths and generalized Debye length scales

TL;DR

This paper derives a universal high-temperature correlation function form for multicomponent systems, enabling extraction of microscopic interactions and revealing diverging correlation lengths and generalized Debye scales in systems with long-range interactions.

Contribution

It introduces a universal correlation function form at high temperatures and links diverging correlation lengths to generalized Debye scales in long-range interacting systems.

Findings

Universal high-temperature correlation function derived

Effective microscopic interactions can be extracted from measurements

Diverging correlation lengths with vanishing amplitudes identified in long-range systems

Abstract

We derive a universal form for the correlation function of general n component systems in the limit of high temperatures or weak coupling. This enables the extraction of effective microscopic interactions from measured high temperature correlation functions. We find that in systems with long range interactions, there exist diverging correlation lengths with amplitudes that tend to zero in the high temperature limit. For general systems with disparate long range interactions, we introduce the notion of generalized Debye length (and time) scales and further relate it to the divergence of the largest correlation length in the high temperature (or weak coupling) limit.