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.
References
F.G. Eich, E.K.U. Gross, Phys. Rev. Lett. 111, 156401 (2013)
K. Capelle, G. Vignale, B.L. Györffy, Phys. Rev. Lett. 87, 206403 (2001)
S. Sharma, J.K. Dewhurst, C. Ambrosch-Draxl, S.K. Helbig, N. Helbig, S. Pittalis, S. Shallcross, L. Nordström, E.K.U. Gross, Phys. Rev. Lett. 98, 196405 (2007)
S.Y. Savrasov, Phys. Rev. Lett. 81, 2570 (1998)
K. Karlsson, F. Aryasetiawan, Phys. Rev. B 62, 3006 (2000)
T. Kotani, M. van Schilfgaarde, J. Phys.: Condens. Matter 20, 295214 (2008)
P. Buczek, A. Ernst, P. Bruno, L.M. Sandratskii, Phys. Rev. Lett. 102, 247206 (2009)
E. ŞaŞioğlu, A. Schindlmayr, C. Friedrich, F. Freimuth, S. Blügel, Phys. Rev. B 81, 054434 (2010)
S. Lounis, A.T. Costa, R.B. Muniz, D.L. Mills, Phys. Rev. B 83, 035109 (2011)
B. Rousseau, A. Eiguren, A. Bergara, Phys. Rev. B 85, 054305 (2012)
K. Cao, H. Lambert, P.G. Radaelli, F. Giustino, Phys. Rev. B 97, 024420 (2018)
M.C.T.D. Müller, C. Friedrich, S. Blügel, Phys. Rev. B 94, 064433 (2016)
S.V. Halilov, H. Eschrig, A.Y. Perlov, P.M. Oppeneer, Phys. Rev. B 58, 293 (1998)
O. Grotheer, C. Ederer, M. Fähnle, Phys. Rev. B 63, 100401 (2001)
F. Essenberger, S. Sharma, J.K. Dewhurst, C. Bersier, F. Cricchio, L. Nordström, E.K.U. Gross, Phys. Rev. B 84, 174425 (2011)
G.F. Giuliani, G. Vignale, Linear response theory, in Quantum Theory of the Electron Liquid (Cambridge University Press, Cambridge, 2005), Chap. 3, pp. 111–156
F.G. Eich, S. Pittalis, G. Vignale, Phys. Rev. B 88, 245102 (2013)
G.F. Giuliani, G. Vignale, Linear response of independent electrons, in Quantum Theory of the Electron Liquid (Cambridge University Press, Cambridge, 2005), Chap. 4, pp. 157–187
P. Buczek, A. Ernst, L.M. Sandratskii, Phys. Rev. B 84, 174418 (2011)
G. Shirane, R. Nathans, O. Steinsvoll, H.A. Alperin, S.J. Pickart, Phys. Rev. Lett. 15, 146 (1965)
M.W. Stringfellow, J. Phys. C: Solid State Phys. 1, 950 (1968)
K. Hüller, J. Magn. Magn. Mater. 61, 347 (1986)
S. Pittalis, G. Vignale, F.G. Eich, Phys. Rev. B 96, 035141 (2017)
Author information
Authors and Affiliations
Corresponding author
Additional information
Contribution to the Topical Issue “Special issue in honor of Hardy Gross”, edited by C.A. Ullrich, F.M.S. Nogueira, A. Rubio, and M.A.L. Marques.
Rights and permissions
Open Access 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.
About this article
Cite this article
Eich, F.G., Pittalis, S. & Vignale, G. A shortcut to gradient-corrected magnon dispersion: exchange-only case. Eur. Phys. J. B 91, 173 (2018). https://doi.org/10.1140/epjb/e2018-90253-y
Received:
Revised:
Published:
DOI: https://doi.org/10.1140/epjb/e2018-90253-y