Regensburg 2010 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 33: Topical Session Multifunctional Materials II

MM 33.3: Vortrag

Mittwoch, 24. März 2010, 12:45–13:00, H6

Strain-dependent magnetism of La_0.8Sr_0.2CoO₃ — •Andreas Herklotz¹, Mike Biegalski², Hans Christen², Ludwig Schultz¹, and Kathrin Dörr¹ — ¹IFW Dresden, Germany — ²CNMS, ORNL, USA

Perovskite transition-metal oxides have attracted much attention because of the possibility of tuning the magnetic and electronic properties of thin films through interface effects such as exchange interactions, charge transfer, and epitaxial strain.

We investigate the strain-dependence of epitaxial LSCO (La_0.8Sr_0.2CoO₃) thin films in two ways. First, we grow LSCO in different strain states on PMN-PT(001) (0.72PbMg_1/3Nb_2/3O₃-0.28PbTiO₃) substrates. Compositionally controlled LASO (LaAl_1−xSc_xO₃) buffer layer serve to allow for a tunable lattice strain not affected by the underlying substrate. Second, we use the ferroelectric PMN-PT substrates to biaxial compress as-grown films reversibly by more than 0.1%.

Our experiments show that biaxial strain suppresses ferromagnetism. We have recorded a decrease in the average Co magnetic moment and the transition temperature with increasing tensile strain from as grown films. The dynamic strain experiments help to gain further insight into phase-separated cobaltites and indicate a domination of the double exchange. A considerable change of the Co spin state cannot be observed.