Effect of partial metamagnetic and magnetic transition coupling on the magnetocaloric effect of Ni-Mn-Sn-Fe alloy

For Ni-Mn-Z based (Z = Sn, In, Sb) alloys, the martensite transformation (MT) and magnetic transition in austenite state create opposite magnetic cooling effect, which offsets each other when the first-order MT (FOMT) coincides with the second-order magnetic transition (SOMT). In the present study, two successive magnetization peaks are introduced in a Ni48.4Fe1.1Mn38.5Sn12.0 alloy by creation of a partial overlap between reverse MT and magnetic transition in the austenite phase with 1.1 at.% Fe-doping. In addition, significant enhancement of the magnetization difference (Delta M) between martensite/austenite phases is achieved. Consequently, an inverse magnetocaloric effect (IMCE) associated with a positive isothermal magnetic entropy change (Delta S-M) of 9.6 J/kg.K and a working temperature interval (Delta T-FWHM) of 306-314 K is found under an external magnetic field of 5.0 T in the reverse MT and T-C(A) temperature range. This IMCE is followed by a conventional magnetocaloric effect (CMCE) with a negative Delta S-M of -2.7 J/kg.K and Delta T-FWHM of 316-339 K under 5.0 T. By taking advantage of these two successive MCEs using a special designed device, large caloric cooling effect with enhanced working temperature interval may be of interesting for practical room-temperature refrigeration applications.