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Magnetic and structural phase transitions in the La0.88MnOx system

Igor Troyanchuk 1Vladimir A. Khomchenko 1Henryk Szymczak Klaus Barner 2

1. The Institute of Solid State & Semiconductor Physics, National Academy of Science of Belarus, 17 P.Brovka, Minsk 220072, Belarus
2. Universitat Gottingen, IY. Physikalisches Institut, Gottingen, Germany


The study of crystal structure, magnetic and electrotransport properties of La0.88MnOx (2.82<=x<=2.96) manganites as a function of oxygen content has been carried out using X-ray, neutron diffraction, elastic modulus, magnetization and resistivity measurements. The crystal structure of investigated compounds has been found to be orthorhombic at x<2.91 and monoclinic at x>=2.91. The gradual transition from an orbitally-ordered state to an orbitally-disordered one is observed up to the concentration range of monoclinic compounds. Strong correlation between the type of orbital state and magnetic properties has been revealed. It has been shown that orbital-ordered orthorhombic compounds (2.82<=x<=2.84) are antiferromagnets while orbital-disordered monoclinic ones (x>=2.92) are metallic ferromagnets which reveal the features of first-order transition to paramagnetic state. Compositions in the wide range of oxygen concentration 2.85<=x<=2.91 exhibit both an antiferromagnetic and a ferromagnetic component. Simultaneously, the neutron diffraction and elastic properties study suggest the coexistence of both orbitally-ordered and orbitally-disordered phases. The properties are discussed in the framework of structurally driven phase separation model.


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

Submitted: 2003-05-08 16:02
Revised:   2009-06-08 12:55