Single-ion anisotropy of localized-electron compounds

Abstract

We present a computational analysis of the influence of taking the full multiplet structure into account in calculations of the single-ion contribution to the magnetocrystalline anisotropy ͑MCA͒ of 3d transition-metal ͑TM͒ ions in localized-electron compounds at Tϭ0 K. For atoms with d n (nϭ1 -4,6-9) configurations, at sites with a local cubic, tetragonal, or trigonal symmetry the single ion MCA on the basis of the Hund's rule ground state term only ͓crystal field ͑CF͒ theory͔ is compared with the single-ion MCA on the basis of a fully relativistic first principles atomic theory including the intra-atomic d-d interaction. Solid state effects are taken into account by effective crystal fields and the exchange field. Under certain, realistic, conditions the use of the full multiplet theory is shown to have a significant effect on the calculated single-ion MCA. We also discuss the effect on the overall cubic anisotropy constants for cubic crystals containing transition metal atom sublattices for which the d-metal atoms are located on sites with a local tetragonal and trigonal symmetry. Possible refinements of the theory are discussed.

Tensor description of X-ray magnetic dichroism at the Fe L 2,3-edges of Fe3O4

“…In the case of Fe 2+ , however, the coupling between the orbital and spin momenta results in a scenario where neither the spin nor the orbital moments follow the rotation of the magnetic field [see Fig. 8(b)] due to the magnetocrystalline anisotropy (Alders et al, 2001). The spin moment can be phase shifted from the direction of the magnetic field with $ 0.5 while the orbital moment can lag $ 4 in some directions.…”

Exchange constants and spin waves of the orbital-ordered noncollinear spinel MnV2O4

“…The parameters of the model are: [1] the exchange constants J derived from the LSDA+U (+SO) converged charge densities using linear response theory and the magnetic force theorem 20,21 , and [2] the singleion anisotropy parameters D calculated using an exactdiagonalization atomic multiplet procedure 14 . We input these parameters into the Heisenberg model Hamiltonian with anisotropy terms, minimize the classical energy to find the stable ground state configuration, and calculate the spin-wave excitation spectra.…”

“…The low-T magnetic excitations of the compound have been mapped along high-symmetry directions using inelastic neutron scattering 3,13 . At the Γ point, these excitations are gapped for the acoustic modes, indicating the presence of single-ion anisotropy, which essentially occurs due to the interplay between SOC and crystal-fields 14 . In Ref.…”

“…17. In this work, we report our study of MnV 2 O 4 based on the LSDA+U method and using linear muffin-tin orbital (LMTO) basis set to solve the electronic structure problem 18,19 . We calculate the pair-wise interatomic magnetic exchange interactions (J) between all magnetic atoms using linear response theory and magnetic force theorem 20,21 , including the single-ion anisotropies (D) for Mn and V found by the exact diagonalization procedure 14 . We then use the obtained J and D as parameters in a Heisenberg Hamiltonian with anisotropy to derive the spin-wave spectra in a semiclassical approximation.…”

Magnetic structure of theS=1Ni5(TeO3Pregelj1, Zorko2, Berger3 et al. 2007Phys. Rev. B133340View full textAdd to dashboardCite

“…We stress that single-ion anisotropy is frequently very relevant for Ni 2+ ions in distorted ͓NiO 6 ͔ octahedra. [9][10][11][12] Furthermore, there is almost no symmetry restriction for the Dzyaloshinsky-Moriya antisymmetric exchange interaction, 13 which is thus, in principle, allowed for each Ni pair.…”