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MA: Fachverband Magnetismus
MA 15: Poster:ThinFilms(1-33),Transp.(34-49),ExchBias(50-56),
Spindynamics(57-70),Micro-nanostr.Mat.(71-82),
Particles/Clust.(83-88), Mag.Imag./Surface(89-96),
Spinelectronics(97-109), Theory/Micromag.(110-116),
Spinstruct/Phasetr.(117-128),Magn.Mat.(129-139),
Aniso.+Measuring(140-145), MolMag.(146-152),
MSMA(153-156)
MA 15.5: Poster
Tuesday, March 27, 2007, 15:00–19:00, Poster A
Synthesis, Structure, and Magnetism of the Electron-Doped Cobaltates La1−xCexCoO3 — •Christian Pinta1,2, Dirk Fuchs1, Peter Adelmann1, Thorsten Schwarz1,2, Peter Schweiss1, Stefan Mangold3, and Stefan Schuppler1 — 1Forschungszentrum Karlsruhe, Institut für Festkörperphysik, 76021 Karlsruhe, Germany — 2Universität Karlsruhe, Fakultät für Physik, 76128 Karlsruhe, Germany — 3Forschungszentrum Karlsruhe, Institut für Synchrotronstrahlung, 76021 Karlsruhe, Germany
Electron doping of lanthanum cobaltate, LaCoO3, with doping levels exceeding minute values had been impossible until recently, when we succeeded in synthesizing epitaxial thin films of the system La1−xCexCoO3 (0.1 ≤ x ≤ 0.4) using pulsed laser deposition. In these thin films, ferromagnetic order is observed within the entire doping range, with the maximum of the Curie temperature, TC, occurring at x ≈ 0.3. This results in a magnetic phase diagram similar to that of hole-doped lanthanum cobaltates. The measured spin values suggest an intermediate-spin state of the Co ions which has been also found in the hole-doped system. However, in contrast to the hole-doped material where TC is well above 200 K, we observe a strong suppression of the maximum TC to about 22 K. In order to study possible effects of distortions or disorder on TC, the local spatial and electronic structure of the films was investigated in more detail by x-ray absorption spectroscopy (NEXAFS and EXAFS), illustrating that the material is indeed electron-doped, and showing an increased structural distortion of La1−xCexCoO3 compared to the undoped cobaltates.