Doping-dependent orbital magnetism in Chromium pnictides

TL;DR

This study explores how electron doping influences the orbital magnetism and magnetic phases in LaCrAsO, revealing a sequence of magnetic states linked to electron localization and orbital characteristics.

Contribution

It provides a detailed phase diagram of LaCrAsO under doping, highlighting the orbital-dependent magnetic transitions using the matrix random-phase approximation.

Findings

Low doping stabilizes antiferromagnetic order consistent with experiments.

Increased doping favors stripe-type antiferromagnetism.

High doping leads to incommensurate magnetic phases linked to specific orbitals.

Abstract

We present results for the phase diagram of the parent compound LaCrAsO under electron doping using the matrix random-phase approximation. At low doping levels, the system stabilizes an antiferromagnetic state in which different Cr sublattices carry opposite spins, consistent with experimental observations. As the doping concentration increases, a stripe-type antiferromagnetic phase becomes favored. At even higher doping, the system repeats the two former magnetic states, but with incommensurate magnetic ordering vectors. The commensurate magnetic phases are associated with more localized electrons in the Cr $d_{3z^2-r^2}$ orbital, whereas the incommensurate phases are linked to the $d_{xy}$ orbital, whose stronger overlap favors itinerant-electron magnetism.