Calculations Of Magnetic Anisotropy Energy Research Articles

Comparative study of tight-binding and ab initio electronic structure calculations focused on magnetic anisotropy in ordered CoPt alloy

An empirical multiorbital (spd) tight binding (TB) model including magnetism and spin–orbit coupling is applied to calculations of magnetic anisotropy energy (MAE) in CoPt L10 structure. A realistic Slater–Koster parametrisation for single-element transition metals is adapted for the ordered binary alloy. Spin magnetic moment and density of states are calculated using a full-potential linearised augmented plane-wave (LAPW) ab initio method and our TB code with different variants of the interatomic parameters. Detailed mutual comparison of this data allows for determination of a subset of the compound TB parameters tuning of which improves the agreement of the TB and LAPW results. MAE calculated as a function of band filling using the refined parameters is in broad agreement with ab initio data for all valence states and in quantitative agreement with ab initio and experimental data for the natural band filling. Our work provides a practical basis for further studies of relativistic magnetotransport anisotropies by means of local Green's function formalism which is directly compatible with our TB approach.

ChemInform Abstract: Effect of Spin‐orbit Coupling on the Magnetic Properties of Materials: Theory

AbstractReview: 145 refs.

Magnetic anisotropy energy of antiferromagnetic L1-type equiatomic Mn alloys

The theoretical calculations of magnetic anisotropy energy (MAE) for antiferromagnetic L10-type MnTM [transition metal (TM)=Ni, Pd, Pt, Rh, and Ir] alloys were carried out on the basis of the local spin-density approximation using linear muffin-tin orbital method with atomic sphere approximation including the spin-orbit interaction. It has been demonstrated that the magnitude of the MAE for L10-type MnIr alloy is highest, −20.77×106J∕m3, and the negative sign of the MAE is consistent with the reported spin structure. On the other hand, the sign of the MAE for L10-type MnPt alloy is positive in accordance with the spin structure. The MAE of the MnPt alloy is sensitive to the electron number, which would be correlated with the fact that only the MnPt alloy system exhibits a complicated magnetic phase diagram.

Magnetic anisotropy of transition-metal interfaces from a local perspective: reorientation transitions and spin-canted phases in Pd capped Co films on Pd(111).

Layer-resolved self-consistent electronic calculations of magnetic anisotropy energy (MAE) provide new insight to the off-plane magnetization observed in Pd capped Co films on Pd(111). We demonstrate that the transition from perpendicular to in-plane phases with increasing film thickness involves an intermediate spin-canted phase. The interfaces responsible for the stability of the off-plane easy axes are characterized microscopically. A local analysis of the MAEs reveals an unexpected internal magnetic structure of the Co-Pd interfaces in which the magnetic moments and spin-orbit interactions at the Pd atoms play a crucial role.

The physics of magnetic materials from ab-initio calculations

Recent advances on ab-initio computation of physical properties of magnetic materials are reviewed. The emphasis is put forward regarding the new development of the electronic structure methods, namely the calculation of magnetic anisotropy energy, X-ray magnetic dichroism, non-collinear magnetism, spin density wave, and spin fluctuations in materials. These theoretical advances have lead to new levels of understanding of magnetic materials. In particular, new results on magnetic anisotropy, surface and interface magnetism, and magnetic alloys will be briefly discussed.

Spin Polarised Relativistic Kkr

ABSTRACTWe review spin polarised multiple scattering theory and show how it can provide a description of magnetic anisotropic effects in metallic systems. An interpretation in terms of the leading relativistic corrections is given; namely the interaction between spin-orbit coupling and spin polarisation. It is pointed out that it is straightforward to vary the d-rection of spin polarisation within this formalism. As simple illustrations, the cases of two and three impurities in a non-interacting relativistic' electron gas are outlined and the origin of pseudo-dipolar and Dzyaloshinski-Moriya anisotropy highlighted. We go on to compare and contrast estimates of magneto-crystalline anisotropies of transition metals with those from alternative methods. Finally we discuss the paramagnetic spin susceptibility of metals within this framework and show that this work is complementary to magnetic anisotropy energy calculations. A generalised Stoner condition for the onset and direction of the magnetisation is given. Calculations for h.c.p. metals cobalt, scandium and yttrium are presented. We conclude by pointing out that this approach can be extended to set up a theory for the dynamical susceptibility with consequent implications for anisotropy of spin wave excitations.