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SYNF: Symposium Ferroic materials and novel functionalities

SYNF 1: Ferroic materials and novel functionalities I

SYNF 1.6: Vortrag

Dienstag, 26. Februar 2008, 11:45–12:00, A 151

Strain-dependent magnetism and electric transport properties of La_0.7Sr_0.3CoO₃ films — •Andreas Herklotz, Diana Rata, Orkidia Bilani, Ludwig Schultz, and Kathrin Dörr — IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany

The electronic and magnetic properties of some perovskite-type 3d transition metal oxides are known to be sensitive to epitaxial strain. In order to investigate the influence of strain in La_0.7Sr_0.3CoO₃ (LSCO) compound, epitaxial films under different biaxial strain have been grown using various substrates. Additionally, piezoelectric substrates of the composition 0.72PbMg_1/3Nb_2/3O₃-0.28PbTiO₃ (PMN-28%PT) were employed to control the in-plane strain dynamically by applying an electrical field. An insulator-type behaviour was observed in films grown under tensile strain, whereas compressed films show bulk, metallic properties. This drastic influence of strain was confirmed by using the PMN-PT substrates, where a reversible strain of 0.15% caused a resistance change of one order of magnitude at room temperature. On the contrary, the magnetization data revealed a rather small impact of tensile strain on the magnetic behaviour of LSCO films. We suggest that the insulator state of La_0.7Sr_0.3CoO₃ is caused by a stain-induced static Jahn-Teller-type deformation of the CoO₆ units, which may be efficient as a localization mechanism.