Interstitial boron in MnFe(P,As) giant-magnetocaloric alloy

The influences of boron addition on the phase formation, Curie temperature and magnetic entropy change of the Mn0.95Fe1.05P0.5As0.5 compound have been investigated. All the samples crystallize in the hexagonal Fe2P-type structure and boron enters into the basal plane as an interstitial element. The Curie temperatures can be adjusted by varying the boron content. Strong field-induced itinerant-electron meta-magnetic transitions with small hysteresis are observed. With boron addition in small amounts the giant-magnetocaloric effects are slightly enhanced. This study provides a novel route to tune optimal working temperatures and improve magnetic properties and magnetocaloric effect.