Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 38: Multiferroics

MA 38.3: Vortrag

Donnerstag, 26. März 2009, 15:45–16:00, HSZ 103

Magnetism and magnetotransport of strained epitaxial La_1−xSr_xCoO₃ (x = 0.18; 0.3) films — •Orkidia Bilani-Zeneli, Andreas Herklotz, Diana Rata, Ksenia Boldyreva, Ludwig Schultz, Nadja Kozlova, and Kathrin Dörr — IFW Dresden, Postfach 270116, 01171 Dresden

Perovskite cobaltites La_1−xA_xCoO₃ (A = Sr, Ca) have been investigated in bulk form for the temperature- and pressure-dependent spin state of Co ions for decades. Magnetic studies of epitaxially grown films are rare, but recent work on LaCoO₃ has indicated the potential for strain-controlled magnetism [1].

In this work, films of La_1−xSr_xCoO₃ (x = 0.18; 0.3) have been grown epitaxially on substrates of various lattice mismatch (SrTiO₃, LaAlO₃, LSAT, PMN-PT) by off-axis pulsed laser deposition. Film lattice parameters reveal that large strains can be maintained up to thicknesses beyond 60 nm. The films (x = 0.18; 0.3) are ferromagnetic with huge coercive fields indicating large magnetic anisotropy. The effect of biaxial strain on the Curie temperature and the magnetization has been derived from statically strained films and from reversibly strained films on piezoelectric PMN-PT(001). Interestingly, the strain strongly affects the electrical conduction: tensile strain leads to reduced conductivity and a strain-induced insulator state (x = 0.3) [2]. Data on strain-dependent resistance and magnetoresistance in magnetic fields up to 50 T will be discussed. [1] D. Fuchs et al., PRB 75, 144402 (2007); PRB 77, 014434 (2008) [2] A. D. Rata et al., PRL 100, 076401 (2008)