Magnetic Properties of La_0.8K_0.2MnO₃ Nanoparticles

¹ Institute of Experimental Physics SAS, Watsonova 47, 040 01 Košice, Slovak Republic
² Institute of Geotechnics SAS, Watsonova 45, 040 01 Košice, Slovakia
³ Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, Poland
⁴ Institute of Chemistry, Faculty of Science, PJ Šafárik University, Moyzesova 11, 040 01 Košice, Slovakia

^a Corresponding author: mihalik@saske.sk

Published online: 3 July 2014

Abstract

Magnetic properties of La_0.8K_0.2MnO₃have been studied on nanoparticles prepared by glycine – nitrate method. As prepared nanoparticles and samples annealed at 300°C/2 hours adopt orthorhombic crystal structure (space group Pbnm). Crystal structure and particles size were modified by heat treatment. The exchange bias effect was observed on samples with particles size smaller than 50 nm.Cooling in magnetic field H_cf≠ 0 through the Curie temperature T_Cshifts hysteresis loop in horizontal and vertical direction. The values of exchange bias field H_E, coercive field H_c, remnant asymmetry μ_E and coercive magnetization μ_c increase with increasing value of cooling field H_cf. In addition the training effect was studied. Basic magnetic properties like the Curie temperature T_C and the saturated magnetization μ_sincrease and H_E or μ_E decrease with heat treatment. Heat treatment at 600 °C/2 hours increases the average size of nanoparticles to about 60 nm, crystal structure changes to rhombohedral structure (space group R$$\overline{3}$$c) and EB effect vanishes.