GWstudy of the half-metallic Heusler compounds Co2MnSi and Co2FeSi

Abstract

Quasiparticle spectra of potentially half-metallic Co 2 MnSi and Co 2 FeSi Heusler compounds have been calculated within the one-shot GW approximation in an all-electron framework without adjustable parameters. For Co 2 FeSi the many-body corrections are crucial: a pseudogap opens and good agreement of the magnetic moment with experiment is obtained. Otherwise, however, the changes with respect to the density-functional-theory starting point are moderate. For both cases we find that photoemission and x-ray absorption spectra are well described by the calculations. By comparison with the GW density of states, we conclude that the Kohn-Sham eigenvalue spectrum provides a reasonable approximation for the quasiparticle spectrum of the Heusler compounds considered in this work.

Effect of Coulomb interactions and Hartree-Fock exchange on structural, elastic, optoelectronic and magnetic properties of Co2MnSi Heusler: A comparative study

“…We present in Fig strongly open the band gap [54]. This disparity in results is not limited only to our study, but extends to other results [55] such as GGA-PBE and GW which give a gap of 0.82 eV and 0.95 eV respectively. Unfortunately, no experimental data is available for this system to compare.…”

Quasiparticle band structure of the almost-gapless transition-metal-based Heusler semiconductors

“…Although in principle GW is a more elaborate method to study the band structure of solids since it includes the quasiparticle corrections, its success with respect to standard density functional calculations is not guaranteed and results should be confirmed by experiments. Recently, Meinert et al 15 studied the band structure of the half-metallic ferromagnetic full Heusler compounds, Co 2 MnSi and Co 2 FeSi, via one-shot GW calculations and found that the many-body corrections are crucial especially for the latter system, and experimentally studied spectra of both materials are well described by the GW calculations. In contrast, the band gap of wurtzite ZnO is repeatedly underestimated by more than 1 eV within the GW calculations with respect to its experimental value.…”

Direct observation of half-metallicity in the Heusler compound Co2MnSi

“…By means of various band structure methods many Heusler compounds have been predicted to be 100% spin polarized. For instance, for Co 2 MnSi, several publications predict half-metallicity, with different sizes of the minority charge carrier band gap and position of the Fermi energy6789101112.…”