Berlin 2005 – scientific programme
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MA: Magnetismus
MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65
MA 20.104: Poster
Monday, March 7, 2005, 14:00–18:00, Poster TU C
Atomic structure and magnetic properties of MnSi thin films — •M. Hortamani, P. Kratzer, and M. Scheffler — Fritz Haber Institut der Max-Planck Gesellschaft , Faradayweg 4-6, 14195 Berlin, Germany
Epitaxial manganese silicide compounds are promising candidates as materials for magneto-electronic and spintronic devices. We compare the structural and magnetic properties of Mn-silicide films on Si(111) and Si(001) surfaces using density functional theory calculations performed with the full-potential augmented plane wave plus local orbital method (FP-LAPW+lo). Experimental studies find initial epitaxial growth of Mn or MnxSiy clusters in the Volmer-Weber growth mode on both Si(001) and Si(111) substrates, which later grow together to form a rough thin film in case of Si(111). Our calculations show that ferromagnetic manganese-silicon multilayers are the most stable epitaxial films on both surfaces. These films have a CsCl-like atomic structure with a lattice mismatch of less than 2% to the substrate. Their formation is exothermic in thermodynamic equilibrium with bulk Mn, and endothermic in equilibrium with bulk MnSi. Moreover, MnSi films with CsCl-like structure on Si(111) are found to be more stable than films of other epitaxial silicides, such as Mn3Si or Mn5Si3. The Mn magnetic moments are as high as 1.8 µB at the surfaces and interfaces, and saturate at 0.3 µB in the interior of the film. The calculated spin polarization at the Fermi level for CsCl-like MnSi on Si is higher than 30% and for the (001) interface, and 35% for the (111) interface, which opens up the possibility for a highly spin-polarized current to be injected into the Si substrate.