Importance of effective dimensionality in manganese pnictides

TL;DR

This study uses advanced computational methods to analyze two manganese pnictides, revealing how their differing effective dimensionalities influence magnetic and electronic properties, aligning well with experimental data.

Contribution

It demonstrates the crucial role of effective dimensionality in determining properties of manganese pnictides using charge self-consistent DFT+DMFT calculations.

Findings

LaMnAsO is quasi-two-dimensional, BaMn₂As₂ is more three-dimensional.

Differences in Nél temperature, band gap, and optical spectra are linked to effective dimensionality.

Calculations agree well with experimental optical spectra.

Abstract

In this paper we investigate the two manganese pnictides BaMn$_2$As$_2$ and LaMnAsO, using fully charge self-consistent density functional plus dynamical mean-field theory calculations. These systems have a nominally half-filled d shell, and as a consequence, electronic correlations are strong, placing these compounds at the verge of a metal-insulator transition. Although their crystal structure is composed of similar building blocks, our analysis shows that the two materials exhibit a very different effective dimensionality, LaMnAsO being a quasi-two-dimensional material in contrast to the much more three-dimensional BaMn$_2$As$_2$. We demonstrate that the experimentally observed differences in the N\'eel temperature, the band gap, and the optical properties of the manganese compounds under consideration can be traced back to exactly this effective dimensionality. Our calculations show excellent agreement with measured optical spectra.