Enhanced magnetocaloric effect in Heusler Ni–Mn–Sn unidirectional crystal

• A unidirectional crystal of Heusler Ni–Mn–Sn alloy was fabricated.
• The effective refrigeration capacity reached 127 J/kg under a field change of 30 kOe.
• The magnetic properties did not show magnetic anisotropy.

A unidirectional crystal of Heusler Ni–Mn–Sn alloy with L21(2 2 0) preferential orientation was fabricated using a modified high-pressure optical zone-melting furnace in the present work. When a magnetic field was applied parallel to the crystal growth direction, the maximum values of magnetic entropy change in the vicinity of the martensitic transformation and the magnetic transition of austenite were found to be 5.58 J/kg K and −2.87 J/kg K, respectively. The total effective refrigeration capacity reached 127 J/kg under a magnetic field change of 30 kOe. The magnetic properties almost remained constant when the magnetic field was applied a direction perpendicular to the growth direction. Such magnetocaloric effect was ascribed to the relatively lower magnetic anisotropy along both directions, which is advantageous for practical utilization of refrigeration.