Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 41: Focussed Session: Frontiers of Electronic Structure Theory IV (jointly with HL and TT)

O 41.4: Talk

Wednesday, March 13, 2013, 11:30–11:45, H36

First-principles calculation of Hubbard U parameters for half-metallic ferromagnets — •Ersoy Sasioglu, Christoph Friedrich, and Stefan Blügel — Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany

Correlation effects play an important role in the electronic structure of half-metallic ferromagnets (HM-FMs). They give rise to non-quasiparticle states above (or below) the Fermi energy at high temperatures [1], which reduce the spin polarization and as a consequence the efficiency of the spintronics devices. Employing the constrained random-phase approximation (cRPA) [2] within the full-potential linearized augmented-plane-wave (FLAPW) method [3], we have calculated the strength of the effective Coulomb interaction (Hubbard U) between localized 3d electrons in a series of HM-FMs like zincblende MnAs, half- and full-Heusler alloys NiMnSb and Co₂MnSi, respectively. The obtained Hubbard U parameters lie between 2.5 and 4.5 eV, being smallest for MnAs (Mn-3d) and largest for Co₂MnSi (Co-3d). The small value of U in the former can be attributed to the efficient screening of the As p electrons. For HM full-Heusler compounds the obtained U values are comparable to the ones in elementary 3d transition metals, while for half-Heusler compounds the U is a bit smaller.
M. I. Katsnelson et al., Rev. Mod. Phys. 80, 315 (2008).
E. Şaşioğlu et al., Phys. Rev. B 83, 121101(R) (2011).
http://www.flapw.de