Exchange Bias Effect in NdFeO3 System of Nanoparticles

M. Vavraa,b, M. Zentková a, M. Mihalik a, M. Mihalik Jr. a, J. Lazúrová a, V. Girman b, M. Perovic c, V. Kusigerski c, P. Roupcova d and Z. Jaglicic e aInstitute of Experimental Physics, SAS, Watsonova 47, 040 01 Košice, Slovakia bP.J. Šafárik University, Faculty of Science, Košice, Slovak Republic cThe Vinca Institute, University of Belgrade, 11001 Belgrade, Serbia dInstitute of Physics of Materials, ASCR, Zizkova 22, Brno, Czech Republic eMPM & FGG, Jadranska 19, 1000 Ljubljana, Slovenia

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We study the effect of nanometric size on the crystal structure, magnetic environment of iron and magnetization in NdFeO3 system of nanoparticles. The average particle size of NdFeO3 nanoparticles increases with annealing at 600°C from about 15 nm to 40 nm. The smallest particles on annealed sample have size approximately 30 nm and typically have character of single crystalline samples. All samples adopt orthorhombic crystal structure, space group Pnma with lattice parameters a =5.5817 Å, b=7.7663 Å and c =5.456 Å for as prepared sample. The presence of superparamagnetic particles was indicated by the Mössbauer measurements. The reduction of dimensionality induces a decrease of TN1 from 691 K to 544 K. The shift of magnetic hysteresis loop in vertical and horizontal direction was observed at low temperatures after cooling in magnetic field. We attribute such behaviour to exchange bias effect and discuss in the frame of core-shell model.

DOI: 10.12693/APhysPolA.131.869 PACS numbers: 75.47.Lx, 75.50.Tt, 75.70.Rf, 75.60.Jk