Regensburg 2010 – scientific programme

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MA: Fachverband Magnetismus

MA 6: Magnetic Thin Films I (Heusler Alloys)

MA 6.7: Talk

Monday, March 22, 2010, 16:00–16:15, H10

Thin magnetic films of the Heusler compound Co₂FeAl_0.4Si_0.6 — •Frederick Casper¹, Tanja Graf¹, Johannes Paul², Gerhard Jakob³, and Claudia Felser¹ — ¹Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg - University, 55099 Mainz, Germany — ²SENSITEC GmbH, 55131 Mainz, Germany — ³Institute of Physics, Johannes Gutenberg - University, 55099 Mainz, Germany

Half-metallic compounds which are fully spin polarized near the Fermi level (E_F) due to an energy gap in the minority-spin channel have attracted great attention as key materials for creating spintronic devices. Co-based Heusler compounds have been predicted to have a high spin polarization even at room temperature due to their high Curie temperature of around 1000 K. To overcome the problem of narrow energy separation between the Fermi level and the bottom edge of the conduction band, Co₂FeAl_1−XSi_X (CFAS) has been predicted to be more stable against the influence of temperature. For X = 0.5, several reports show promising results with CFAS in magnetic tunnel junctions using MgO and Al₂O₃ as tunnel barrier. Here we show the first results of Co₂FeAl_0.4Si_0.6 films on MgO and SiO_X substrates. Depending on the annealing temperature, buffer layer and substrate, CFAS shows B2 and/ or L2₁ type of order. Magnetic moments ranging from 3.8 to 5.1 µ_B/f.u. depending on the degree of ordering. AFM measurements show smooth surfaces, and XPS reveal the right stoichiometry for all films. This work is supported by the Federal Ministry for Education and Research BMBF, project "‘Multimag"’.