Magnetic Properties of La_0.8K_0.2MnO₃Nanoparticles

Abstract

Abstract.Magnetic properties of La 0.8 K 0.2 MnO 3 have been studied on nanoparticles prepared by glycinenitrate method. As prepared nanoparticles and samples annealed at 300 o 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 C shifts 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 s increase and H E or μ E decrease with heat treatment. Heat treatment at 600 o C/2 hours increases the average size of nanoparticles to about 60 nm, crystal structure changes to rhombohedral structure (space group c R3 ) and EB effect vanishes.