Magnetic field-induced isothermal entropy change across the magnetostructural transition in Ni-Mn-Ga melt-spun ribbons

This study investigates the magnetocaloric effects in Ni-Mn-Ga melt spun ribbons. The ribbons are prepared by single-copper roller melt spinning and vacuum annealed at 1173 K for 18 h. The martensitic transformation temperatures are determined by differential scanning calorimetry whilst the crystal structure is analyzed at room temperature by X-ray diffraction. Magnetization measurements are performed by vibrating sample magnetometry. It is shown that the atomic ordering enhancements as well as the occurrence of the magneto-multistructural transformation play an important role in the remarkable increase of the maximum absolute isothermal entropy change in these Ni-Mn-Ga ribbons.