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MA: Fachverband Magnetismus

MA 35: Magnetic Heusler Compounds I

MA 35.4: Vortrag

Mittwoch, 28. März 2012, 16:00–16:15, H 0112

Electronic, structural, and magnetic properties of the half-metallic ferromagnetic quaternary Heusler compounds CoFeMnZ (Z = Al, Ga, Si, Ge) — •Vajiheh Alijani, Juergen Winterlik, Gerhard Fecher, and Claudia Felser — Institute for Inorganic and analytical Chemistry, Johannes Gutenberg University, 55099 Mainz, Germany

Half-metallic ferromagnets exhibit 100% spin polarization at the Fermi energy and therefore are ideal candidates for spin-injection devices. Several materials besides Heusler compounds have been predicted to exhibit half-metallicity. Several quaternary-or pseudo-ternary Heusler compounds have been designed in order to tailor the middle of the gap exactly to the Fermi energy. For symmetry reasons (T_d), quaternary Heusler compounds with a 1:1:1:1 stoichiometry are substantially different from the L2₁ pseudo-ternary Heusler compounds with O_h symmetry and 2:[(1−x):x]:1 or 2:1:[(1−y):y] stoichiometry.

The quaternary intermetallic Heusler compounds CoFeMnZ (Z = Al, Ga, Si, Ge) with 1:1:1:1 stoichiometry were predicted to exhibit half-metallic ferromagnetism by ab-initio electronic structure calculations. The compounds were synthesized using an arc-melting technique and the crystal structures were analyzed using X-ray powder diffraction. The electronic properties were investigated using HAXPES. The low-temperature magnetic moments, as determined from magnetization measurements, follow the Slater-Pauling rule, confirming the proposed high spin-polarizations. All compounds have high Curie-temperatures, allowing for applications at room temperature and above.