The structural, magnetic and magnetocaloric properties of Ni ₂ Mn _{1+ x} In _{1− x} alloys, prepared using an arc-melting furnace in an argon environment, have been studied for their potential application in cost-effective magnetic refrigeration technology. The room-temperature x-ray diffraction shows that the Ni ₂ Mn _{1+ x} In _{1− x} alloys with 0 ⩽ x ⩽ 0.34 exhibit austenite cubic phase, whereas the alloys with x > 0.34 have mixed tetragonal martensite and cubic austenite phases. The Ni ₂ Mn _1.34 In _0.66 alloy shows a clear second-order phase transition with a Curie temperature of 305 K but its elemental composition is very close to the critical composition between first and second–order phase transitions. The calculated magnetic entropy change and relative cooling power of the Ni ₂ Mn _1.34 In _0.66 alloy measured at 3 T field are 4.5 J kg ⁻¹ K ⁻¹ and 201 J kg ⁻¹ , respectively. The temperature dependent resistivity of Ni ₂ Mn _1.34 In _0.66 alloy measured at H = 0 Oe shows that the sample has a room temperature resistivity of 7 The absence of thermal and magnetic hysteresis due to second-order magnetic phase change, coupled with higher values of magnetic entropy change and relative cooling power, suggests that the Ni ₂ Mn _1.34 In _0.66 alloy has the potential for magnetic refrigeration.

Permanent-magnet materials are one cornerstone of today’s technology, abundant in disk drives, motors, medical equipment, wind generators, and cars. A continuing challenge has been to reconcile high permanent-magnet performance with low raw-material costs. This work reports a Mn-Bi-Sn alloy exclusively made from inexpensive elements, exhibiting high values of Curie-temperature, magnetization, anisotropy, coercivity, and energy product. The samples are produced by field annealing of rapidly quenched Sn-containing MnBi alloys, where the improvement of the magnetic properties is caused by the substitutional occupancy of the 2c sites in the hexagonal NiAs structure by Sn. The substitution modifies the electronic structure of the compound and enhances the magnetocrystalline anisotropy, thereby improving the coercivity of the compound. The energy product reaches 114 kJ/m³ (14.3 MGOe) at room temperature and 86 kJ/m³ (10.8 MGOe) at 200 °C; this value is similar to that of the Dy-free Nd₂Fe₁₄B and exceeds that of other rare-earth-free permanent-magnet bulk alloys, as encountered in automotive applications.

We performed combined theoretical and experimental studies of electronic, structural, and magnetic properties of Fe₂MnSn Heusler alloy. The density functional theory calculation shows that the Fe₂MnSn alloy has two energetically close phases, namely, hexagonal D0₁₉ and cubic L2₁, which agrees well with the experimental results. Both the hexagonal and cubic phases are ferromagnetic, with large magnetization values of about 6 μ_B/f.u. and high Curie temperature above room temperature. The hexagonal phase shows high magnetic anisotropy of 5.1 Merg/cm³. These findings may be interesting for magnetic applications where large saturation magnetization, high Curie temperature, and high magnetic anisotropy are desired.

The growth of new magnetic materials on suitable insulating substrates is an important part of the development of spin-electronics devices for memory or information processing. Epitaxial thin films of Mn₂PtSn were grown on a MgO [001] substrate by magnetron co-sputtering of the constituents. Structural, magnetic, and electron-transport properties were investigated. The epitaxial Mn₂PtSn film has an inverse tetragonal structure with the c-axis aligned in the plane of the MgO substrate. The lattice constants determined using XRD and TEM analysis are c = 6.124 Å and a = b = 4.505 Å. The orientation of Mn₂PtSn c-axis which is 45° away from the a-axis of MgO has resulted in a small lattice mismatch of about 2.8%. The measured saturation magnetization is 5.3 μ_B/f.u., which is smaller than the first-principles calculated value of 6.4 μ_B/f.u. for ferromagnetic spin arrangement. Magnetization measurements determined the bulk magnetocrystalline anisotropy constant K_v of about 11.3 Merg/cm³ (1.13 MJ/m³). The electron-transport behavior is similar to that of normal magnetic metals. These results indicate that Mn₂PtSn may have promising applications in spintronic devices.

The structural, magnetic, and electron-transport properties of Mn_3−xPt_xSn (x = 0, 0.5, 1) nanomaterials prepared by arc-melting, melt-spinning, and annealing were investigated. It was found that the hexagonal structure is the most stable structure for Mn₃Sn and the samples show an antiferromagnetic spin order at room temperature. The Pt-containing samples are mainly tetragonal but contain a small amount of other impurity phases, including hexagonal Mn₃Sn and Mn₂Sn. At room temperature, the Pt-containing samples show ferri- or ferromagnetic spin order with a Curie temperature of about 370 K. The measured high-field magnetization and anisotropy constant for Mn₂PtSn are 405 emu/cm³ and 2.6 Mergs/cm³, respectively. The samples are all highly conducting with metallic electron transport and show a substantial negative magnetoresistance.