This title appears in the Scientific Report :
2010
Please use the identifier:
http://dx.doi.org/10.1103/PhysRevB.81.054434 in citations.
Please use the identifier: http://hdl.handle.net/2128/10999 in citations.
Wannier-function approach to spin excitations in solids
Wannier-function approach to spin excitations in solids
We present a computational scheme to study spin excitations in magnetic materials from first principles. The central quantity is the transverse spin susceptibility, from which the complete excitation spectrum, including single-particle spin-flip Stoner excitations and collective spin-wave modes, can...
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Personal Name(s): | Sasioglu, E. |
---|---|
Schindlmayr, A. / Friedrich, C. / Freimuth, F. / Blügel, S. | |
Contributing Institute: |
Quanten-Theorie der Materialien; IFF-1 Jülich Aachen Research Alliance - High-Performance Computing; JARA-HPC JARA-FIT; JARA-FIT Quanten-Theorie der Materialien; IAS-1 |
Published in: | Physical Review B Physical review / B, 81 81 (2010 2010) 5 5, S. 054434 054434 |
Imprint: |
College Park, Md.
APS
2010
|
Physical Description: |
054434 |
DOI: |
10.1103/PhysRevB.81.054434 |
Document Type: |
Journal Article |
Research Program: |
European Theoretical Spectroscopy Facility I3 Grundlagen für zukünftige Informationstechnologien |
Series Title: |
Physical Review B
81 |
Subject (ZB): | |
Link: |
Get full text OpenAccess OpenAccess |
Publikationsportal JuSER |
Please use the identifier: http://hdl.handle.net/2128/10999 in citations.
We present a computational scheme to study spin excitations in magnetic materials from first principles. The central quantity is the transverse spin susceptibility, from which the complete excitation spectrum, including single-particle spin-flip Stoner excitations and collective spin-wave modes, can be obtained. The susceptibility is derived from many-body perturbation theory and includes dynamic correlation through a summation over ladder diagrams that describe the coupling of electrons and holes with opposite spins. In contrast to earlier studies, we do not use a model potential with adjustable parameters for the electron-hole interaction but employ the random-phase approximation. To reduce the numerical cost for the calculation of the four-point scattering matrix we perform a projection onto maximally localized Wannier functions, which allows us to truncate the matrix efficiently by exploiting the short spatial range of electronic correlation in the partially filled d or f orbitals. Our implementation is based on the full-potential linearized augmented-plane-wave method. Starting from a ground-state calculation within the local-spin-density approximation (LSDA), we first analyze the matrix elements of the screened Coulomb potential in the Wannier basis for the 3d transition-metal series. In particular, we discuss the differences between a constrained nonmagnetic and a proper spin-polarized treatment for the ferromagnets Fe, Co, and Ni. The spectrum of single-particle and collective spin excitations in fcc Ni is then studied in detail. The calculated spin-wave dispersion is in good overall agreement with experimental data and contains both an acoustic and an optical branch for intermediate wave vectors along the [1 0 0] direction. In addition, we find evidence for a similar double-peak structure in the spectral function along the [1 1 1] direction. To investigate the influence of static correlation we finally consider LSDA+U as an alternative starting point and show that, together with an improved description of the Fermi surface, it yields a more accurate quantitative value for the spin-wave stiffness constant, which is overestimated in the LSDA. |