Investigation of the structural, magnetic, and magnetocaloric properties in the La₀.₆Ca₀.₂Sr₀.₂MnO₃ compound

Abstract

In this study, we investigated the structural, magnetic, and magnetocaloric properties, the blocking temperature (TB), and exchange bias (EB) behaviour of a La₀.₆Ca₀.₂Sr₀.₂MnO₃ (LCSMO) compound prepared by solid-state reaction. X-ray diffraction analysis, using Rietveld refinement, showed that the sample crystallize in an orthorhombic structure with the Pbnm space group. Scanning electron microscopy (SEM) confirmed the formation of a single-phase material with an excellent distribution map and the average particle size of \(37.8723 \pm 0.5536\) nm. The M-T curve revealed second-order magnetic phase transitions at the Curie temperature (T_C = 340 K), shifting from a paramagnetic (PM) to ferromagnetic (FM) state. Our results reveal significant magnetic entropy changes, indicating a substantial magnetocaloric effect. Notably, the magnetic entropy change reaches a peak value of 5.763 J/kg.K accompanied by a considerable relative cooling capacity of 335 J/kg, observed under a magnetic field change of 5 T. Hysteresis measurements indicate the presence of a double coercive field leading to an exchange bias (EB) effect in the La₀.₆Ca₀.₂Sr₀.₂MnO₃ manganite compound. The coercivity went from 296.46 Oe (23.6 kA.m⁻¹) at 5 K to 96.23 Oe (7.65 kA.m⁻¹) at ambient temperature indicating soft ferromagnetic behaviour of the studied sample; thus, it is suitable for the production of electromagnetic devices and ultra-high recording devices. To understand the nature and mechanisms behind the phase transition from paramagnetic (PM) to ferromagnetic (FM) states, an analysis of critical exponents was performed. The critical exponents derived from the modified Arrott plots (\(\beta =0.36615\pm 0.0048\)) and (\(\gamma =1.32846\pm 0.02092\)) closely align with the prediction of the 3D-Heisenberg model.