Dresden 2011 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 44: Magnetic Half-metals and Oxides I
MA 44.4: Vortrag
Mittwoch, 16. März 2011, 17:45–18:00, HSZ 401
Spin-states in the single-layered cobaltates — •Dirk Fuchs1, Michael Merz1, Levin Dieterle3, Stefan Uebe1,2, Markus Wissinger1,2, Andrea Assmann1,2, Peter Nagel1, Rudolf Schneider1, Stefan Schuppler1, Dagmar Gerthsen3, and Hilbert v. Löhneysen4 — 1Karlsruher Institut für Technologie, Institut für Festkörperphysik, Karlsruhe, Germany — 2Karlsruher Institut für Technologie, Fakultät für Physik, Karlsruhe, Germany — 3Karlsruher Institut für Technologie, Laboratorium für Elektronenmikroskopie, Karlsruhe, Germany — 4Karlsruher Institut für Technologie, Physikalisches Institut, Karlsruhe, Germany
The delicate balance between the crystal-field (CF) splitting and Hund‘s rule coupling results in different possible spin-states - high-spin, low-spin (LS) and intermediate-spin state - of the Co ion and thus in an additional degree of freedom in the cobaltates. Since the CF splitting is very sensitive to hydrostatic, chemical or epitaxial pressure the cobaltates provide large playground for artificial spin-state manipulation. For example, epitaxial tensile strain is able to suppress a low-temperature spin-state transition to a LS-state in LaCoO3 films [1]. Therefore, it is very likely that the spin blockade in the layered cobaltates can be suppressed by tensile strain of the CoO2 layers too. With respect to this, the influence of chemical and epitaxial pressure on the spin-state of La2−xAxCoO4 (A = Ca, Sr or Ba) cobaltates was investigated. Bulk samples as well as thin films were prepared and the structural and magnetic properties were characterized in detail.
[1] D. Fuchs et al. Phys. Rev B 75, 144402 (2007).