Dresden 2006 – wissenschaftliches Programm
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MA: Magnetismus
MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)
MA 20.154: Poster
Dienstag, 28. März 2006, 15:15–19:15, P1
Is non-ideal Co2MnSi still a half-metal? — •Björn Hülsen, Peter Kratzer, and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
Material systems for spintronics applications have recently attracted much interest and one promising candidate is the full Heusler alloy Co2MnSi . In its pure bulk phase, this material has a high Curie temperature and displays a gap in the density of states at the Fermi level in the minority spin channel leading to 100 % spin polarization. However, even in the cleanest sample the (theoretically) perfect configuration of atoms is disturbed due to a finite concentration of structural defects.
To see whether Co2MnSi maintains its half-metallic character under more realistic conditions we performed all-electron density functional theory calculations for several disordered and non-stochiometric unit cells using the spin-polarized generalized gradient approximation and the full-potential LAPW+lo method. We investigated the stability, the magnetic properties, and the electronic structure of the Co2+xMn1−xSi (−1 < x < 0.75) compounds with i) exchanged Co and Mn atoms ii) Mn atoms replaced by Co, and iii) Co atoms replaced by Mn.
We find that in the Co-Mn-interchanged and Co-rich compounds, although there is still large spin polarization, the gap is closed, while it is preserved in the Mn-rich compositions.