A comparative study of magnetic, and magnetocaloric properties of different transition metal-doped La0.67Sr0.33AO3 (A: Mn, Co, Cr, and Fe) samples

Abstract

In the present work, structural, magnetic, and magnetocaloric properties of La0.67Sr0.33AO3 (A: Mn, Co, Cr and Fe) samples were examined. XRD analyses revealed that all samples produced by the sol–gel method and subjected to the same grinding and heat treatment steps crystallized in the perovskite crystal structure. In order to examine the magnetic behavior of the samples, temperature-dependent magnetization (M(T)) measurements were carried out. It was found that La0.67Sr0.33MnO3, which has the highest magnetization value, has the highest Curie temperature (T C = 368.2 K). In order to determine the magnetic phase transition order and calculate magnetic entropy change (- Δ SM) value, field-dependent magnetization (M(H)) measurements in the transition temperature region were carried at zero field-cooled (ZFC) and field-cooled (FC) processes. The maximum magnetic entropy change (-ΔSMmax) of La0.67Sr0.33MnO3 sample was calculated as 1.5 Jkg−1 K−1 under 1 T magnetic field change. La0.67Sr0.33CoO3 sample, in which antiferromagnetic (AFM) and ferromagnetic (FM) interactions coexist, exhibits a paramagnetic (PM)-FM phase transition at 244.1 K. At 1 T magnetic field change, the (-ΔSMmax) was found to be 0.145 Jkg−1 K−1 for this sample. La0.67Sr0.33CrO3 and La0.67Sr0.33FeO3 samples showed weak FM properties due to the different magnetic interactions originating from the ions in the B-sites of the samples. The magnetic phase transition is second-order for all samples.