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We report on the magnetic, magnetoelastic, as well as the specific heat measurements of the electron-doped manganite Ca 0.85 Sm 0.15 MnO 3. The low-temperature monoclinic phase which is antiferromagnetic exhibits a first-order field-induced transition into the ferromagnetic state. This transition is accompanied by a strong decrease in volume. The latent heat calculated from the Clapeyron-Clausius equation coincides with that of the structural phase transition determined from the specific heat measurements. We thus deduce that the observed metamagnetic transition in Ca 0.85 Sm 0.15 MnO 3 is due to the field-induced structural transformation from the monoclinic phase to the orthorhombic phase.

In order to understand the electronic origin of the inverse magnetocaloric effect observed in a Ni–Co–Mn–In system we used a combination of indirect experimental probes as magnetization, resistivity and specific heat. The findings are compared with the band structure of isostructural Heusler alloys such as Ni–Mn–Ga. We suggest that the inverse magnetocaloric effect in Ni–Co–Mn–In originates from the high density of states close to Fermi energy. Within the austenite state this causes ferromagnetic band splitting. The structural change to the martensite allows an alternative way to reduce the high density of states at lower temperatures, which does not require band splitting and thus does not support ferromagnetic order.

Ferromagnetic Heusler alloys exhibiting martensitic transformations are known to change their shape in an external magnetic field. Magnetization, electric resistance, and specific heat as a function of temperature are examined in Ni 54 Fe 19 Ga 27 single crystal. Structural transition appears as sharp anomaly in these dependencies. This points to an avalanchelike character of martensitic transformation. The jump in resistivity at the structural phase transition and the lower density of states at the Fermi level in the martensite phase supports the hypothesis of the Jahn-Teller origin of the martensitic transformation. Magnetic measurements show that transformation to the martensitic phase is accompanied by the increase of spontaneous magnetization and an increase of magnetocrystalline anisotropy. Magnetization increase is due to different Curie temperatures of austenite and martensite. These were determined from critical behavior using Arrott plot. Additional analysis of magnetic behavior indicates ferrimagnetic ordering in this nonstoichiometric compound. Intrinsic properties of the compound are analyzed with respect to both of the actuation modes possible in magnetic shape-memory alloys. However, neither a magnetically induced martensite transformation nor a magnetically induced reorientation of variants has been observed.

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