Advanced

Calculation of Chern number spin Hamiltonians for magnetic nano-clusters by DFT methods

Strandberg, Olof LU ; Canali, Carlo LU and MacDonald, A H (2008) In Physical Review B (Condensed Matter and Materials Physics) 77(17). p.19-174416
Abstract
By combining field-theoretical methods and ab initio calculations, we construct an effective Hamiltonian with a single giant-spin degree of freedom, which is capable of describing the low-energy spin dynamics of ferromagnetic metal nano-clusters consisting of up to a few tens of atoms. In our procedure, the magnetic moment direction of the Kohn-Sham spin density functional wave function is constrained by means of a penalty functional, which allows us to explore the entire parameter space of directions, and to extract the magnetic anisotropy energy and Berry curvature functionals. The average of the Berry curvature over all magnetization directions is a Chern number-a topological invariant that can only take on values equal to multiples of... (More)
By combining field-theoretical methods and ab initio calculations, we construct an effective Hamiltonian with a single giant-spin degree of freedom, which is capable of describing the low-energy spin dynamics of ferromagnetic metal nano-clusters consisting of up to a few tens of atoms. In our procedure, the magnetic moment direction of the Kohn-Sham spin density functional wave function is constrained by means of a penalty functional, which allows us to explore the entire parameter space of directions, and to extract the magnetic anisotropy energy and Berry curvature functionals. The average of the Berry curvature over all magnetization directions is a Chern number-a topological invariant that can only take on values equal to multiples of one-half, which represents the dimension of the Hilbert space of the effective spin system. The spin Hamiltonian is obtained by quantizing the classical anisotropy energy functional, after performing a change of variables to a constant Berry curvature space. The purpose of this paper is to examine the impact of the topological effect from the Berry curvature on the low-energy total-spin-system dynamics. To this end, we study small transition-metal clusters: Co-n (n=2,...,5), Rh-2, Ni-2, Pd-2, MnxNy, and Co3Fe2. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review B (Condensed Matter and Materials Physics)
volume
77
issue
17
pages
19 - 174416
publisher
American Physical Society
external identifiers
  • wos:000256763800070
  • scopus:43549090864
ISSN
1098-0121
DOI
10.1103/PhysRevB.77.174416
language
English
LU publication?
yes
id
a98ef173-d55d-4d2b-9037-5f43cb52d339 (old id 1190546)
date added to LUP
2008-09-08 09:59:02
date last changed
2017-01-01 06:10:36
@article{a98ef173-d55d-4d2b-9037-5f43cb52d339,
  abstract     = {By combining field-theoretical methods and ab initio calculations, we construct an effective Hamiltonian with a single giant-spin degree of freedom, which is capable of describing the low-energy spin dynamics of ferromagnetic metal nano-clusters consisting of up to a few tens of atoms. In our procedure, the magnetic moment direction of the Kohn-Sham spin density functional wave function is constrained by means of a penalty functional, which allows us to explore the entire parameter space of directions, and to extract the magnetic anisotropy energy and Berry curvature functionals. The average of the Berry curvature over all magnetization directions is a Chern number-a topological invariant that can only take on values equal to multiples of one-half, which represents the dimension of the Hilbert space of the effective spin system. The spin Hamiltonian is obtained by quantizing the classical anisotropy energy functional, after performing a change of variables to a constant Berry curvature space. The purpose of this paper is to examine the impact of the topological effect from the Berry curvature on the low-energy total-spin-system dynamics. To this end, we study small transition-metal clusters: Co-n (n=2,...,5), Rh-2, Ni-2, Pd-2, MnxNy, and Co3Fe2.},
  author       = {Strandberg, Olof and Canali, Carlo and MacDonald, A H},
  issn         = {1098-0121},
  language     = {eng},
  number       = {17},
  pages        = {19--174416},
  publisher    = {American Physical Society},
  series       = {Physical Review B (Condensed Matter and Materials Physics)},
  title        = {Calculation of Chern number spin Hamiltonians for magnetic nano-clusters by DFT methods},
  url          = {http://dx.doi.org/10.1103/PhysRevB.77.174416},
  volume       = {77},
  year         = {2008},
}