Direct and Inverse Magnetocaloric effects in A-site ordered PrBaMn2O6 manganite in low magnetic fields

The magnetocaloric effect (MCE) of A-site ordered PrBaMn2O6 manganite has been studied by direct methods and by the specific heat measurements. Direct measurements of the MCE in low magnetic fields were performed using recently proposed modulation technique and by classic direct method in high fields. Direct and inverse MCE are observed at Curie and Neel points correspondingly. A value of the inverse MCE in the heating run is less than in the cooling regime. This effect can be attributing to competition between ferromagnetic and antiferromagnetic interactions. Indirectly estimated and direct MCE values considerably differ in around first order AF transition.Comment: 8 pages, 5 figure

Structure and magnetocaloric properties of La1-xKxMnO3 manganites

A technology of obtaining the single-phase ceramic samples of La1-xKxMnO3 manganites and the dependence of their structural parameters on the content of potassium has been described. Magnetocaloric effect (MCE) in the obtained samples has been measured by two independent methods: by classical direct methodic and by a method of magnetic field modulation. The values of MCE obtained by both methods have been substantially differed. The explanation of the observed divergences is given. The correlation between the level of doping and MCE value has been defined. The value of TC determined by the MCE maximum has been conformed to the literature data received by other methods.Comment: 14 pages, 6 figures, 3 table

???????????????????????? ?? ?????????????????????????????????????? ???????????? ?? ???????????????????? La0.7SrxBa0.3-xMnO3

Results of an experimental study of the heat capacity (Cp), as well as direct and indirect measurements of the MCE (???T, ???S) of La0.7Sr0.3-xBaxMnO3 samples (x = 0, 0.02, 0.05, 0.10) in the temperature range 80???400 K and in magnetic fields up to 1.8 T are presented. It is shown that the partial substitution of barium (Ba) for strontium (Sr) shifts TC and insignificantly decreases the magnetocaloric effect. The maximum value of the change in entropy in a field of 1.8 T is ???S = 1.6 J/kg??K for x = 0.02. The entropy change associated with the disordering of the magnetic system during the ferromagnetic-paramagnetic phase transition is estimated. ?? 2021 Pirogov Russian National Research Medical University. All rights reserved

Electrical and magnetic properties of La₁₋xAgyMnO₃ recrystallized ceramics

A method is presented to obtain silver-containing lanthanum manganites La₁₋xAgyMnO₃₊δ exhibiting GMR. Ceramic samples possessing high Curie temperature and showing a sharp maximum of metal-insulator transition near Curie temperature have been obtained.Представлен способ получения серебросодержащего манганита лантана, обладающего КМС. Получены керамические образцы, обладающие высокой температурой Кюри и проявляющие резкий максимум перехода металл-изолятор в области температуры Кюри.Представлено спосіб одержання срібловмісного манганіту лантану, що має КМС. Отримано керамічні зразки, які мають високу температуру Кюрі та виявляють різкий максимум переходу метал-ізолятор поблизу температур Кюрі

Determination of the magnetocaloric effect from thermophysical parameters and their relationships near magnetic phase transition in doped manganites

We present the results of a comparative analysis of the magnetocaloric effect (MCE) in Pr(0.7)Sr(0.2)Ca(0.1)NnO(3), through direct and indirect measurements, using experimentally measured magnetization, specific heat, magnetostriction, resistivity, thermal diffusivity and thermal conductivity parameters. We have demonstrated that the change in each parameter in response to a magnetic field near the ferromagnetic-paramagnetic phase transition temperature of the material correlates with the change in magnetic entropy. These findings allow us to interrelate these parameters and provide an alternative, effective approach for accessing the usefulness of magnetocaloric materials