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MA: Fachverband Magnetismus

MA 24: Magnetic Heusler Compounds

MA 24.3: Vortrag

Dienstag, 17. März 2020, 10:00–10:15, HSZ 403

Theoretical Approach for Simulation of the Magnetic and Magnetocaloric properties of Ni-Mn-Ga Heusler Alloys — •Olga Miroshkina, Vladimir Sokolovskiy, Danil Baigutlin, Mikhail Zagrebin, and Vasiliy Buchelnikov — Chelyabinsk State University, 454001 Chelyabinsk, Russia

In this paper, we study the magnetic and magnetocaloric properties of Ni1+xMn1-xGa (x = 0.16, 0.18, and 0.3) Heusler alloys. These compositions belong to the three different regions of the (T-x) phase diagram and illustrate different sequences of phase transitions. The study is performed using the theoretical model based on the Malygin theory of the smeared phase transitions, Bean-Rodbell theory of the first-order phase transitions, and the mean-field theory. The temperature dependences of the deformation, magnetization, and isothermal entropy change of the alloys under study are investigated. It is shown that the largest change in magnetic entropy is observed for Ni2.18Mn0.82Ga, in which the martensitic transition is accompanied by a change in the magnetic ordering. The smallest change in entropy is found for Ni2.3Mn0.7Ga, in which the magnetocaloric effect is observed at ferro-paramagnetic phase transition in the martensite. However, the refrigeration capacity of this composition is twice as large as for the other considered ones. This is due to the fact that the temperature range in which the MCE takes place is significantly wider as compared to the other compositions considered. This work was supported by Russian Foundation for Basic Research No. 18-32-00507.