Dresden 2006 – scientific programme

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MA: Magnetismus

MA 24: Magnetic Thin Films III

MA 24.2: Talk

Thursday, March 30, 2006, 10:30–10:45, HSZ 03

Modeling of structural domains in La_1−xSr_xMnO₃ thin films — •Nayel Farag¹, Manfred Bobeth¹, and Alexei E. Romanov² — ¹Institut für Werkstoffwissenschaft, Technische Universität Dresden, Germany — ²Ioffe Physico-Technical Institute, St. Petersburg, Russia

The magnetic behavior of La_1−xSr_xMnO₃ (LSMO) thin films is essentially affected by elastic strain within the film. Besides a uniform strain contribution due to the lattice-parameter misfit between LSMO and a cubic substrate, additional non-uniform strain contributions arise from the formation of structural domains in coherently grown rhombohedral LSMO films. Observations of domain patterns reported in the literature show perpendicular and inclined domain walls on (100) and (110) oriented SrTiO₃ substrates, respectively. We have calculated the domain-related strain fields by applying the coherency-defect technique. The strain exhibits peaks at the triple junctions of the domain walls and the film/substrate interface. On the base of a model by Millis et al (1998), the corresponding spatial variation of the transition temperature to the ferromagnetic state has been estimated. Furthermore, the domain widths for the different domain patterns on (100) and (110) SrTiO₃ have been calculated as a function of the film thickness. Comparison of the predicted domain width with experimental findings permits to estimate the domain-wall energy.