Critical phenomena in superlattices: Reentrant dimensional crossover and anomalous critical amplitudes

TL;DR

This paper investigates the complex critical phenomena in superlattices, revealing a reentrant dimensional crossover and anomalous critical amplitudes, with persistent large-scale fluctuations across a broad temperature range.

Contribution

It introduces the concept of a reentrant dimensional crossover in superlattices and analyzes its impact on critical amplitudes and fluctuations.

Findings

Reentrant dimensional crossover occurs in superlattices.

Anomalous critical amplitudes are observed.

Large-scale critical fluctuations persist over wide temperature ranges.

Abstract

A crossover from $d$ to $d-1$, and then back to $d$-dimensional critical behavior is argued to be a generic feature characterizing ordering in a $d$-dimensional superlattice composed of atomically {\em thick} films of two ferromagnets. The crossover leads to anomalous changes in the amplitudes of critical singularities. In $d=3$ Heisenberg and $XY$ superlattices large scale critical fluctuations persist over a wide temperature range.