Local Structure of Mn in (La1-xHox)2/3Ca1/3MnO3 Studied by X-ray Absorption Fine Structure

A. Pietnoczkaa, M. Pękałab, R. Bacewicza, V. Drozdc, J.F. Fagnardd, P. Vanderbemdend, J. Antonowicza and W. Zalewskia a Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, Poland b Department of Chemistry, University of Warsaw, al. Żwirki i Wigury 101, 02-089 Warsaw, Poland c Center for Study Matter at Extreme Conditions, Florida International University, Miami, USA d Montefiore Electricity Institute, University of Liege, 4000 Liege, Belgium

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Results of X-ray absorption fine structure measurements in manganites (La1-xHox)2/3Ca1/3MnO3 with 0.15 < x < 0.50 are presented. When LaMnO3 is doped with a divalent element such as Ca2+, substituting for La3+, holes are induced in the filled Mn d orbitals. This leads to a strong ferromagnetic coupling between Mn sites. Ca ions in La1-xCaxMnO3 introduce a distortion of the crystal lattice and mixed valence Mn ions (Mn3+ and Mn4+). On the other hand, in manganites (La1-xHox)2/3Ca1/3MnO3 the substitution of La for Ho causes a lattice distortion and induces a disorder, which reduces a magnetic interaction. The ferromagnetic transition temperature and conductivity decrease very quickly with increasing x. The magnetic and transport properties of compounds depend on the local atomic structure around Mn ions. The information on the bond lengths and Debye-Waller factor are obtained from the extended X-ray absorption fine structure (EXAFS) data analysis. The charge state of Mn is determined from the position of the absorption edge in X-ray absorption near edge structure (XANES) data. XAFS results are in good agreement with magnetic characteristics of the studied materials.

DOI: 10.12693/APhysPolA.117.281 PACS numbers: 61.05.cj, 75.47.Lx, 87.64.kd