Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 29: Magnetische Materialien

MA 29.5: Vortrag

Dienstag, 8. März 2005, 16:15–16:30, TU A060

Co₂FeSi : A half metallic full Heusler compound with high Curie temperature — •Sabine Wurmehl¹, Gerhard H. Fecher¹, Vadim Ksenofontov¹, Hong-Ji Lin², Hans-Joachim Elmers¹, and Claudia Felser¹ — ¹Johannes Gutenberg - Universität, 55099 Mainz, Germany — ²NSRRC, Hsinchu 30077, Taiwan

Co₂FeSi crystallizes in the ordered L2₁ structure as proofed by X-ray diffraction. Mößbauer spectroscopy exhibits a single site for the Fe atom indicating a high local order in the samples. Magnetic hysteresis was measured by SQUID from 5K to 775K revealing a magnetic moment of 6µ_B at low temperature. This value of the magnetic moment is in agreement with the Slater-Pauling rule for half metallic ferromagnets. Plotting the Curie temperature of Co₂ based Heusler compounds versus magnetic moment suggests that Co₂FeSi will have one of the highest magnetic transition temperatures. Here, the Curie temperature was measured with DTA to be about 1030K. Magnetic circular dichroism spectra excited by soft X-rays (XMCD) were taken to determine the element specific magnetic moments of Co and Fe. The electronic and magnetic structure of the compound was calculated self-consistently by means of different methods. These SCF calculations revealed the measured magnetic moment and a half metallic ferromagnetic character only if an appropriate lattice parameter was used.

(This work is funded by the DFG in FG 559.)