Magnetic Properties of Melt-Spun Ribbons of Heusler Ni37Co13Mn35Ti15 Alloy under External Pressure

Samples of the Heusler alloy of 3d metals, Ni37Co13Mn35Ti15 alloy, were obtained in the form of ingots and melt-spun ribbons. Their magnetic properties were studied using a direct method in magnetic fields up to μ0H = 0.94 T and external hydrostatic pressures up to P = 12 kbar. It is shown that the temperatures of the first-order magnetostructural phase transition shift under pressure with a coefficient dTm/dP = +4.5 K/kbar and the Curie temperature is virtually independent of the applied pressure. The structural and magnetic properties of the alloy were studied under pressure using density functional theory methods. It is shown theoretically that the ground magnetic states of the austenitic and martensitic phases are ferromagnetic and ferrimagnetic, with a total magnetic moment of 5.85 μB and 2.37 μB, respectively. Application of external pressure increases the energy barrier between austenite and martensite, explaining the experimentally observed increase of Tm with pressure.