Orbital contribution to the magnetic properties of iron as a function of dimensionality

Abstract

The orbital contribution to the magnetic properties of Fe in systems of decreasing dimensionality (bulk, surfaces, wire and free clusters) is investigated using a tight-binding hamiltonian in an $s,p,$ and $d$ atomic orbital basis set including spin-orbit coupling and intra-atomic electronic interactions in the full Hartree-Fock (HF) scheme, i.e., involving all the matrix elements of the Coulomb interaction with their exact orbital dependence. Spin and orbital magnetic moments and the magnetocrystalline anisotropy energy (MAE) are calculated for several orientations of the magnetization. The results are systematically compared with those of simplified hamiltonians which give results close to those obtained from the local spin density approximation. The full HF decoupling leads to much larger orbital moments and MAE which can reach values as large as 1${\mu }_B$ and several tens of meV, respectively, in the monatomic wire at the equilibrium distance. The reliability of the results obtained by adding the so-called Orbital Polarization Ansatz (OPA) to the simplified hamiltonians is also discussed. It is found that when the spin magnetization is saturated the OPA results for the orbital moment are in qualitative agreement with those of the full HF model. However there are large discrepancies for the MAE, especially in clusters. Thus the full HF scheme must be used to investigate the orbital magnetism and MAE of low dimensional systems.

References in corpus (12)

• Applications of a tight-binding total energy method for transition and noble metals: Elastic Constants, Vacancies, and Surfaces of Monatomic Metals
• Magnetism of iron: from the bulk to the monoatomic wire
• Giant Anisotropic Magneto-Resistance in ferromagnetic atomic contacts
• Magnetocrystalline Anisotropy Energy of Transition Metal Thin Films: A Non-perturbative Theory
• Anomalous Ferromagnetism of Monatomic Co Wire at the Pt(111) Surface Step Edge
• Magnetism in systems with various dimensionality: A comparison between Fe and Co
• Orbital Polarization in Itinerant Magnets
• Non-collinear magnetism in iron at high pressures
• Effect of electron correlations in Pd, Ni, and Co monowires
• Emerging Magnetism in Platinum Nanowires
• Magnetocrystalline anisotropy and orbital polarization in ferromagnetic transition metals
• Orbital contribution to the magnetic properties of nanowires: Is the orbital polarization ansatz justified?

Cited by in corpus (12)

• Magnetic anisotropies of late transition metal atomic clusters
• Excitation of local magnetic moments by tunnelling electrons
• Parametrization of LSDA+$U$ for noncollinear magnetic configurations: Multipolar magnetism in UO${}_2$
• Magnetocrystalline anisotropy energy of Fe$(001)$, Fe$(110)$ slabs and nanoclusters: a detailed local analysis within a tight-binding model
• Electronic transport in iron atomic contacts: from the infinite wire to realistic geometries
• Hubbard-like Hamiltonians for interacting electrons in s, p and d orbitals
• Anisotropic magnetoresistance in ferromagnetic atomic-sized metal contacts
• Defect states and excitations in a Mott insulator with orbital degrees of freedom: Mott-Hubbard gap versus optical and transport gaps in doped systems
• Magnetocrystalline anisotropy of Fe and Co slabs and clusters on SrTiO$\_3$ by first-principles
• Giant orbital moments are responsible for the anisotropic magnetoresistance of atomic contacts
• Sub-10 nm Quantification of Spin and Orbital Magnetic Moment Across the Metamagnetic Phase Transition in FeRh Using EMCD
• The microscopic Einstein-de Haas effect