Magnetic Properties of La0.8K0.2MnO3 Nanoparticles

Abstract

Magnetic properties of La0.8K0.2MnO3have 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 Hcf≠ 0 through the Curie temperature TCshifts hysteresis loop in horizontal and vertical direction. The values of exchange bias field HE, coercive field Hc, remnant asymmetry μE and coercive magnetization μc increase with increasing value of cooling field Hcf. In addition the training effect was studied. Basic magnetic properties like the Curie temperature TC and the saturated magnetization μsincrease and HE or μE 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 R3¯$\bar 3$c) and EB effect vanishes.