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Two-dimensional exchange interaction in perovskite-like manganites.

Maria Mikhaylova 1Natalia Bobrysheva 2Do Kyung Kim 1Muhammet S. Toprak 1Therese Eriksson 3Yvonne B. Andersson 3Mamoun Muhammed 1

1. Royal Institute of Technology, Dept of Materials Science and Engineering, Materials Chemistry Division (KTH), Brinellvaegen 23, 2tr., Stockholm SE10044, Sweden
2. Chemistry Department, Saint Petersburg State University, Saint-Petersburg, Russian Federation
3. Uppsala University, Department of Materials Chemistry, Angstrom Laboratory, Uppsala, Sweden


Nano-dimensional effects, such as electronic phase separation and charge ordering, play an important role in GMR-manganites. These effects are associated with superexchange interaction between Mn(III) and Mn(IV) atoms in perovskite structure. The correlations between properties of La1-xAxMnO3 (A - Sr, Ba) and their electronic structure are still under investigations. Problems yet to be solved include determination of local electron parameters in three-dimensional oxides. The study of low-dimensional systems such as two-dimensional perovskite-like diluted manganites based on La0.75Sr1.25 MnO4 is expected to have a solution to this problem. La0.75Sr1.25 MnO4 complex oxide contains heterovalent manganese atoms and the same type of exchange interactions. In this study the homogeneous solid solutions y(La0.75Sr1.25MnO4) - (1-y)LaSrAlO4 (0.0041<y<0.093) with K2NiF4 structure were synthesized by solid state reaction. The phase in the final product was determined by XRD. Inter-atomic distances were calculated from structure refinements performed by the Rietveld method. Magnetic susceptibility and ESR spectroscopy were used to characterize the samples. According to the results of magnetic susceptibility measurements a strong tendency to clustering in perovskite layers was observed. Thus, the local distribution of electron density was changed. The origin of such phenomenon and its influence on the properties of manganities will be discussed in details.
This work is supported by Russian Foundation of Basic Researches (Grant 03-03-32355).


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Presentation: poster at E-MRS Fall Meeting 2003, Symposium D, by Maria Mikhaylova
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-05-27 19:49
Revised:   2009-06-08 12:55