Regensburg 2000 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 19: Metall-Isolatorüberg
änge

TT 19.7: Vortrag

Donnerstag, 30. März 2000, 11:15–11:30, H18

Strain wave in La_0.9Sr_0.1MnO₃ thin films. — •Assunta Vigliante¹, Adrian Rühm¹, Peter Wochner¹, Ulrich Gebhardt¹, Helmut Dosch¹, F. Razavi², and H.Ulrich Habermeier² — ¹MPI-MF, Heisenbergstr.1,70569 Stuttgart, Germany — ²MPI-FKF, Heisenbergstr.1,70569 Stuttgart, Germany

Epitaxial thin films of La_1−xSr_xMnO₃ with x=0.1, have been grown on SrTiO₃ substrate by pulsed laser ablations. The thickness of the films ranges from 25nm to 250nm. Chemical analysis indicates that the films are homogenous. Recent transport measurements on these films have shown an anomalous metal insulator transition for films less than 500 Å thick at the ferromagnetic phase transition, whereas for thicker films no such transition was observed. In order to gain a better microscopic understanding between structure and trasport properties a detailed X-ray crystallographic analysis was performed. For films less than 500 Å thick, strong scattering was detected near four incommensurate positions (± 0.018, 0, 4) and (0, ± 0.018, 4). We attribute the presence of these superlattice peaks to a compressive in-plane strain modulation of the thin film of wavelength 200 Å. Temperature dependence of the superlattice peaks was also measured and it correlates to the temperature depe