Magnetic and magnetocaloric properties of as-cast Gd2In

This paper presents results of experimental studies of magnetic and magnetocaloric properties of as-cast polycrystalline samples of a Gd2In intermetallic compound, which crystallizes into a hexagonal structure of the Ni2In type. Measurements of the field and temperature dependences of the magnetization carried out in a temperature range from 50 to 300 K and in magnetic fields up to 3 T showed that the as-cast Gd2In samples undergo ferromagnetic ordering upon cooling below Curie temperature ТС =194 K. With further cooling, a metamagnetic transition from the ferromagnetic into an antiferromagnetic phase is observed at a temperature Tm = 95 K, which is accompanied by pronounced anomalies in the temperature and field dependences of the magnetization. An external magnetic field stabilizes the ferromagnetic phase, shifting Tm toward low temperatures. The isothermal magnetic entropy change in the ΔSm, calculated using the Maxwell relation, shows a peak at the Curie temperature, which, when the magnetic field changes from 0 to 3 T, reaches its maximum value ΔSm = −3.25 J / kg ∙ K. The temperature dependence of ΔSm clearly indicates a crossover of the magnetocaloric effect from direct to inverse one, which occurs in the vicinity of the metamagnetic transition. The experimental data obtained in our work on unannealed Gd2In samples are in a good qualitative and quantitative agreement with the data published for the annealed Gd2In samples. Thus, the results of this work indicate that the attainment of a homogeneous state in polycrystalline Gd2In samples, which can affect their magnetic properties, can occur during cooling of the as-cast ingot on a cold crucible and does not require an additional heat treatment.

Complex investigations of phase diagram of Ni-Pt-Mn-Ga Heusler alloys

M. Zagrebin, S. Derevyanko, V. Sokolovskiy, V. Buchelnikov

1. Russian Science Foundation - No. 18-42-06201