Small hysteresis and giant magnetocaloric effect in Nb-substituted (Mn,Fe)2(P,Si) alloys

Abstract The influence of Nb substitution on the structure, magnetoelastic transition and magnetocaloric properties has been investigated for the Mn1.1Fe0.85-xNbxP0.43Si0.57 alloys. The substitution for Fe by merely 4.7 at.% Nb (i.e. x = 0.04) significantly diminishes the thermal hysteresis from 10 to 1 K due to the reduced structural discontinuity crossing the magnetoelastic transition. This also improves the mechanical stability. The Curie temperature of the magnetoelastic transition is lowered by approximately 11.6 K per at.% of the Nb substitution, originating from the enhanced covalent bonding that favors the paramagnetic state. The giant magnetocaloric effect is still retained in the Nb-substituted alloys.