High temperature martensitic transformation and giant magnetocaloric effect in Ni40Co10Mn41Sn9 melt-spun ribbons

Abstract

"We report a large magnetic entropy change associated with a high-temperature martensitic transformation in Ni40Co10Mn41Sn9 (at. %) melt-spun ribbons. The ribbons underwent a first-order forward martensitic transition and a reverse structural transition from the paramagnetic six-layered modulated martensite to a ferromagnetic austenite in the temperature range of 395–380?K. For a magnetic field change of 5?T (2?T), extremely large magnetic entropy changes of 33.9 (25) J kg?1 K?1 and 53 (22) J kg?1 K?1 upon reverse and forward martensitic transformations occurred. These values are among the largest for Ni-Mn based Heusler alloys reported so far. As compared with the large values upon heating, hysteresis losses upon cooling were negligibly low (only 0.36?J?kg?1). The present findings open up the possibility of elevated temperature magnetic cooling."