https://doi.org/10.1140/epjb/e2018-90253-y
Regular Article
A shortcut to gradient-corrected magnon dispersion: exchange-only case★
1
Max Planck Institute for the Structure and Dynamics of Matter,
Luruper Chaussee 149,
22761
Hamburg, Germany
2
Istituto Nanoscienze, Consiglio Nazionale delle Ricerche,
Via Campi 213A,
41125
Modena, Italy
3
Department of Physics and Astronomy, University of Missouri,
Columbia,
Missouri
65211, USA
a e-mail: florian.eich@mpsd.mpg.de
Received:
13
April
2018
Received in final form:
22
May
2018
Published online: 1
August
2018
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.
© The Author(s) 2018. This article is published with open access at Springerlink.com
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
