Orbital contribution to the magnetic properties of nanowires: Is the orbital polarization ansatz justified?

TL;DR

This paper investigates the magnetic properties of Fe monatomic nanowires, demonstrating that full Hartree-Fock calculations are essential for accurate results, especially in unsaturated systems, challenging the adequacy of the orbital polarization ansatz.

Contribution

It shows that full Hartree-Fock treatment is necessary for accurate magnetic property predictions in low-dimensional systems, questioning the validity of the orbital polarization ansatz.

Findings

Full HF scheme yields significant orbital magnetic moments and anisotropy energies.

Orbital polarization ansatz is insufficient for unsaturated nanowire systems.

Full HF approach is crucial for low-dimensional magnetic systems.

Abstract

We show that considerable orbital magnetic moments and magneto-crystalline anisotropy energies are obtained for a Fe monatomic wire described in a tight-binding method with intra-atomic electronic interactions treated in a full Hartree Fock (HF) decoupling scheme. Even-though the use of the orbital polarization ansatz with simplified Hamiltonians leads to fairly good results when the spin magnetization is saturated this is not the case of unsaturated systems. We conclude that the full HF scheme is necessary to investigate low dimensional systems.