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Title: A shortcut to gradient-corrected magnon dispersion: exchange-only case

Abstract

Ab initio calculations of the magnon dispersion in ferromagnetic materials typically rely on the adiabatic local density approximation (ALDA) in which the effective exchange-correlation field is everywhere parallel to the magnetization. These calculations, however, tend to overestimate the “magnon stiffness”, defined as the curvature of the magnon frequency vs. wave vector relation evaluated at zero wave vector. Here we suggest a simple procedure to improve the magnon dispersion by taking into account gradient corrections to the ALDA at the exchange-only level. We find that this gradient correction always reduces the magnon stiffness. The surprisingly large size of these corrections (~30%) greatly improves the agreement between the calculated and the observed magnon stiffness for cobalt and nickel, which are known to be overestimated within the ALDA.

Authors:
ORCiD logo [1];  [2];  [3]
  1. Max Planck Institute for the Structure and Dynamics of Matter, Hamburg (Germany)
  2. Istituto Nanoscienze, Modena (Italy)
  3. Univ. of Missouri, Columbia, MO (United States)
Publication Date:
Research Org.:
Univ. of Missouri System, Columbia, MO (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1509907
Grant/Contract Number:  
FG02-05ER46203
Resource Type:
Accepted Manuscript
Journal Name:
European Physical Journal. B, Condensed Matter and Complex Systems
Additional Journal Information:
Journal Volume: 91; Journal Issue: 8; Journal ID: ISSN 1434-6028
Publisher:
Springer
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS

Citation Formats

Eich, Florian G., Pittalis, Stefano, and Vignale, Giovanni. A shortcut to gradient-corrected magnon dispersion: exchange-only case. United States: N. p., 2018. Web. doi:10.1140/epjb/e2018-90253-y.
Eich, Florian G., Pittalis, Stefano, & Vignale, Giovanni. A shortcut to gradient-corrected magnon dispersion: exchange-only case. United States. doi:10.1140/epjb/e2018-90253-y.
Eich, Florian G., Pittalis, Stefano, and Vignale, Giovanni. Wed . "A shortcut to gradient-corrected magnon dispersion: exchange-only case". United States. doi:10.1140/epjb/e2018-90253-y. https://www.osti.gov/servlets/purl/1509907.
@article{osti_1509907,
title = {A shortcut to gradient-corrected magnon dispersion: exchange-only case},
author = {Eich, Florian G. and Pittalis, Stefano and Vignale, Giovanni},
abstractNote = {Ab initio calculations of the magnon dispersion in ferromagnetic materials typically rely on the adiabatic local density approximation (ALDA) in which the effective exchange-correlation field is everywhere parallel to the magnetization. These calculations, however, tend to overestimate the “magnon stiffness”, defined as the curvature of the magnon frequency vs. wave vector relation evaluated at zero wave vector. Here we suggest a simple procedure to improve the magnon dispersion by taking into account gradient corrections to the ALDA at the exchange-only level. We find that this gradient correction always reduces the magnon stiffness. The surprisingly large size of these corrections (~30%) greatly improves the agreement between the calculated and the observed magnon stiffness for cobalt and nickel, which are known to be overestimated within the ALDA.},
doi = {10.1140/epjb/e2018-90253-y},
journal = {European Physical Journal. B, Condensed Matter and Complex Systems},
number = 8,
volume = 91,
place = {United States},
year = {2018},
month = {8}
}

Journal Article:
Free Publicly Available Full Text
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Cited by: 2 works
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Figures / Tables:

Fig. 1 Fig. 1: Sketch of a typical transverse magnetic absorption spectrum based on a spin-polarized uniform electron gas (density of states of magnetic excitations). The Stoner continuum is shown as the green-shaded area and the dispersion relation of the magnons is highlighted as the red curve outside the Stoner continuum. Formore » a ferromagnetic material – in the absence of spin-orbit coupling – the dispersion relation starts from zero energy at zero momentum, which reflects the fact that a global rotation of the spins does not change the energy of the ferromagnet (Goldstone mode).« less

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    Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.