Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 26: Magnetic Thin Films I of 2

MA 26.4: Vortrag

Mittwoch, 13. März 2013, 10:15–10:30, H3

La₂CrWO₆: A Possible Antiferromagnet Half-Metal — •Mehran Vafaee, Mehrdad Baghaie Yazdi, Vikas Shabadi, Philipp Komissinskiy, and Lambert Alff — Institute of Materials Science, Technische Universität Darmstadt, Petersenstr. 23, 64287 Darmstadt, Germany

Half-metallic antiferromagnets, materials with zero net magnetization and 100% spin polarization of charge carriers, are promising for spintronic applications, but have never been synthesized up to now. La₂CrWO₆ with d³-d³ configuration has been suggested as a strong candidate based on density functional theory [1]. However, due to the unusual valence state of W³⁺, this material is thermodynamically unstable. For the first time, we report the thin film synthesis of La₂CrWO₆ by pulsed laser deposition. X-ray absorption spectroscopy at the Cr K-edge and W L_2,3-edges show +3 valence state for Cr and a mixed valence state of +3 / +5 for W. X-ray linear dichroism confirms undistorted Cr octahedra symmetry. The magnetization shows ferrimagnetic instead of antiferromagnetic behavior. X-ray magnetic dichroism measurements indicate that antisite disorder is responsible for the reduced W magnetic moment. Thus, suppression of antisite disorder is an important strategy to obtain half-metallic antiferromagnets in double perovskites.

[1] V. Pardo and W. E. Pickett, Phys. Rev. B 80, 054415 (2009).