Calculation of magnetocrystalline anisotropy energy in NdCo₅

Abstract

The magnetocrystalline anisotropy energy (MAE) of NdCo5 was studied from first principles using the full potential linearized augmented plane wave (FLAPW) method. The LDA + U method was used to take into account the effects of strong electronic correlations of 4f states. In agreement with experiments, the magnetization points into the crystallographic a‐axis in the basal plane. The in‐plane MAE was also studied and the correct magnetization direction was arrived at but the magnetic anisotropy constant K3 was about one order of magnitude smaller than the experimental value. The microscopic origin of the MAE in NdCo5 was studied using the orbital moment anisotropy (OMA) and its evolution with lattice geometry. Spin‐reorientation transitions in NdCo5 could be well explained by the competition in OMA between Co and Nd sites. These results show that the non‐equivalent Co sites behave differently with changes in lattice geometry, and the Co3g sites are of the same importance as Nd sites in deciding the in‐plane magnetocrystalline anisotropy of NdCo5. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Magnetization compensation and spin reorientation transition in ferrimagnetic DyCo5 : Multiscale modeling and element-specific measurements

“…Nevertheless, their magnitude is strongly underestimated and insufficient to reach a reorientation transition below the Curie temperature. Thus we needed to adjust these values to d z 2,Co = 0.1 mRyd per ion for each Co sublattice, which is compatible with calculations on other RCo 5 compounds [16]. This discrepancy might be related to the strong dependence of the spin reorientation transition on the exact stoichiometry [31] and lattice constants [16].…”

“…Moreover, DyCo 5 has been proposed to serve as pinning layer for semivolatile ferrimagnetic spin valves [14] and as a storage medium for magnetic-heat-assisted memory devices [15]. Although some theoretical work based on firstprinciples calculations has already been done on the RCo 5 intermetallics [16][17][18][19], we present a model combining fully relativistic ab initio calculations with atomistic spin model simulations based on the stochastic Landau-Lifshitz-Gilbert (LLG) equation of motion. Such a model can give insights into material properties beyond the ground state and at finite temperatures-a crucial requirement, considering the complex temperature dependence of the magnetic phases of these compounds [5,12,13].…”

Correlations in rare-earth transition-metal permanent magnets

“…A good example is the anisotropy of NdCo 5 , based on both published work 8,9 and our own calculations. Uncorrected LSDA calculations, for example, using VASP code with a generalized gradient approximation (GGA), as described in Ref.…”

“…It is sometimes assumed 8 that LSDA þ U accounts for strong 4f correlations and localization, including anisotropy. In fact, the 4f electrons do not become localized via Eq.…”

Magnetic properties of and from the electronic structure calculations

“…Shortly before our paper was sent for publication, a theoretical paper of Pang et al [46] which was focused on anisotropy of magnetic properties (magnetocrystalline anisotropy energy and orbital moment anisotropy) in NdCo 5 was published. LSDA þ U method was used as implemented in WIEN2k code.…”