Microscopic origin of the linear temperature increase of the magnetic susceptibility of BaFe$_{2}$As$_{2}$

TL;DR

This paper explains the linear increase in magnetic susceptibility of BaFe₂As₂ with temperature by linking it to a spectral peak caused by layered structure effects, using advanced theoretical methods.

Contribution

It combines ab initio band structure and dynamical mean-field theory to identify the microscopic origin of the susceptibility anomaly in BaFe₂As₂.

Findings

Spectral peak approximately 100 meV below Fermi level causes susceptibility increase.

Weak dispersion of 2D bands linked to layered structure.

Theoretical explanation matches experimental observations.

Abstract

Employing a combination of \emph{ab initio} band structure theory and dynamical mean-field theory we explain the experimentally observed linear temperature increase of the magnetic susceptibility of the iron pnictide material BaFe$_{2}$As$_{2}$. The microscopic origin of this anomalous behaviour is traced to a sharp peak in the spectral function located approximately 100 meV below the Fermi level. This peak is due to the weak dispersion of two-dimensional bands associated with the layered crystal structure of pnictides.