Anisotropy of the Magnetocaloric Effect in the Ni49.6Mn27.6Ga22.8 Single Crystal
R. Wroblewski, K. Sielicki and M. Leonowicz
Faculty of Material Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw, Poland
Received: February 2, 2015
Full Text PDF
The magnetocaloric effect anisotropy in the Ni49.6Mn27.6Ga22.8 single crystal was investigated. In the examined alloy the structural phase transition and magnetic transition occur at room temperature and around 370 K, respectively. The magnetic entropy change, at those two temperatures, was determined on the basis of isothermal and isofield curves, recorded at fields up to 1200 kA/m (1.5 T) with temperature steps of 2.5 and 5 K. Although the calculated values of magnetic entropy change are relatively small, ≈0.7 J/(kg K), an anisotropy of the magnetocaloric effect is observed with a magnetic field applied along the main crystallographic directions of the single crystal. The magnetic entropy change at the structural phase transition depends on the orientation. The weakest magnetocaloric effect occurs when the field is applied along [1 0 0] direction whereas the highest magnetocaloric effect value is reached along [0 0 1] direction, which is an easy magnetization axis. Such behaviour can be explained with the high magnetocrystalline anisotropy of the martensitic phase. The magnetic entropy change value, at the structural phase transition, obtained for the polycrystalline specimen, is close to that for the [0 0 1] single crystal direction.

DOI: 10.12693/APhysPolA.128.54
PACS numbers:, 75.30.Gw, 75.30.Sg