Antiferromagnetic Critical Fluctuations in BaFe$_2$As$_2$

TL;DR

This study investigates magnetic fluctuations in BaFe$_2$As$_2$ near its antiferromagnetic transition, highlighting a crossover from two-dimensional to three-dimensional critical behavior and its implications for magnetic phase transitions.

Contribution

It provides experimental evidence of two-dimensional magnetic fluctuations and discusses their evolution towards three-dimensional critical behavior in BaFe$_2$As$_2$.

Findings

Observation of two-dimensional magnetic fluctuations over a broad temperature range.

Evidence of a crossover to three-dimensional critical behavior near T$_N$.

Discussion on the role of fluctuations in magnetic phase transition.

Abstract

Magnetic correlations near the magneto-structural phase transition in the bilayer iron pnictide parent compound, BaFe$_2$As$_2$, are measured. In close proximity to the antiferromagnetic phase transition in BaFe$_2$As$_2$, a crossover to three dimensional critical behavior is anticipated and has been preliminarily observed. Here we report complementary measurements of two-dimensional magnetic fluctuations over a broad temperature range about T$_N$. The potential role of two-dimensional critical fluctuations in the magnetic phase behavior of BaFe$_2$As$_2$ and their evolution near the anticipated crossover to three dimensional critical behavior and long-range order are discussed.