Dresden 2009 – scientific programme

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MA: Fachverband Magnetismus

MA 13: Poster Ia: Electron Theory (1); Magnetic Imaging (2,3); Thin Films (4-25); MSMA (26-33); Magn. Semiconductors (34-42); Magn. Half Metals and Oxides (43-60)

MA 13.53: Poster

Tuesday, March 24, 2009, 10:15–13:00, P1A

Thin films of the Heusler compounds Co2FeAl and Co2FeAl0.6Si0.4 — •Elena Arbelo Jorge, Christian Herbort, and Martin Jourdan — Institut of Physics, Johannes-Gutenberg University, Mainz, Germany

Heusler compounds are potential candidates for showing half metallic properties (100% spin polarization) with a large band gap at the Fermi energy and a high Curie temperature above room temperature. Epitaxial thin films of the Heusler compounds Co2FeAl and Co2FeAl0.6Si0.4 were grown by rf sputtering. A study of their crystallographic structure, surface morphology and magnetization has been carried out. For Co2FeAl a B2 structure is found after annealing at 550°C. For Co2FeAl0.6Si0.4 L21 order is found after annealing at the same temperature. The crystallographic order depending on different annealing temperatures is shown. In both compounds a small tetragonal distortion is observed. The surface morphology of each compound is also analysed and compared. Magnetization measurements made in a Quantum Design SQUID magnetometer show a magnetic moment of 4.86μB/f.u and 4.47μB/f.u for Co2FeAl and Co2FeAl0.6Si0.4 annealed at 550°C respectively, which is 2.8% and 17,2% less than the value predicted theoretically from the Slater-Pauling rule for half metals, 5.0μB/f.u and 5.4 μB/f.u, respectively. The magnetic moment depending on different annealing temperatures is presented. Finally, TMR results obtained up to now are shown.