Universal linear-temperature dependence of static magnetic susceptibility in iron-pnictides

TL;DR

This paper reports a universal linear-temperature dependence of magnetic susceptibility in iron-pnictides' normal state, suggesting local antiferromagnetic fluctuations without global magnetic order.

Contribution

It reveals a universal magnetic behavior linked to antiferromagnetic fluctuations, challenging pure itinerant models in iron-pnictides.

Findings

Linear-temperature susceptibility observed across samples

Behavior inconsistent with pure itinerant models

Linked to local antiferromagnetic fluctuations

Abstract

A universal linear-temperature dependence of the uniform magnetic susceptibility has been observed in the nonmagnetic normal state of iron-pnictides. This non-Pauli and non-Curie-Weiss-like paramagnetic behavior cannot be understood within a pure itinerant picture. We argue that it results from the existence of a wide antiferromagnetic fluctuation window in which the local spin-density-wave correlations exist but the global directional order has not been established yet.