Berlin 2005 – wissenschaftliches Programm
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MA: Magnetismus
MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65
MA 20.148: Poster
Montag, 7. März 2005, 14:00–18:00, Poster TU C
Doping and lattice effects in the half-metallic double perovskite A2CrWO6 — •Oliver Sanganas, Stephan Geprägs, Petra Majewski, Andreas Erb, Matthias Opel, Lambert Alff, and Rudolf Gross — Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meißner-Str. 8, 85748 Garching
Ferromagnetic double perovskites have attracted renewed interest due to the fact that they combine high Curie-temperature TC and a half-metallicity [1]. Recently, in the compound Sr2FeMoO6 the substitution of Sr2+ by trivalent La3+ has been reported to lead to an even further increase of TC [2]. With respect to the mechanism of ferromagnetism in the double perovskites it is important to clarify whether this behavior is general [3]. We have fabricated a series of polycrystalline samples of the two compounds with different La doping in order to compare carefully the different effects on TC. All samples were characterized by x-ray powder diffractometry, neutron scattering, magnetization and transport measurements. We find that the preferential formation of LaCrO3 prevents the formation of La-doped Sr2CrWO6. However, in the system Ca2CrWO6 La doping can be achieved. In agreement with the results for Sr2FeMoO6, TC is increased as a function of La doping, paving the way for double perovskites with very high TC as functional material for magnetoelectronics.
[1] K.-I. Kobayashi et al., Nature 395, 677 (1998)
[2] J. Navarro et al., Phys. Rev. B 64, 092411 (2001).
[3] J. B. Philipp et al., Phys. Rev. B 68, 144431 (2003).