Giant magnetocaloric effect in a Heusler Mn50Ni40In10 unidirectional crystal

• A high-quality Mn-rich Heusler Mn50Ni40In10 unidirectional crystal was grown.
• High-pressure optical zone-melting crystal growth technique was used.
• The magnetostructural transitions of the unidirectional crystal were investigated.
• The unidirectional crystal demonstrated giant magnetic refrigeration capacity.

A modified high-pressure optical zone-melting technique was used to grow a Mn-rich Heusler Mn50Ni40In10 unidirectional crystal. Experimental results showed that the produced unidirectional crystal underwent a magnetic transition in austenite, followed with a martensitic transformation from a ferromagnetic austenite to a ferromagnetic martensite upon cooling. Under a magnetic field change of 30 kOe, the total effective refrigeration capacities (RCtotal) reached as high as 231.58 J/kg when the magnetic field was applied along parallel to the crystal growth direction, or 246.79 J/kg when the magnetic field was applied along perpendicular to the crystal growth direction. It was suggested that this unidirectional crystal growing technique may provide an effective approach to enhance the magnetocaloric effect of Mn-rich Heusler materials.