Structural and magnetocaloric properties of (Mn,Fe)2(P,Si) materials with added nitrogen

Amongst magnetic materials that exhibit a giant magnetocaloric effect near room temperature, the(Mn,Fe)2(P,Si) system is one of the most promising candidates for magnetic refrigeration. Although the(Mn,Fe)2(P,Si) materials hold many advantages, controlling the magnetic entropy changeDSm, theadiabatic temperature changeDTad, the thermal hysteresis and the mechanical stability across theferromagnetic transition requires a delicate tuning of the composition. This work investigates theaddition of nitrogen, as an interstitial or substitutional element, as a new parameter to tune the prop-erties of (Mn,Fe)2(P,Si) materials. We found that the nitrogen addition results in a decrease of the Curietemperature, consistent with the observed increase in thec/aratio. The introduction of nitrogen in(Mn,Fe)2(P,Si) materials also results in a strong enhancement of the mechanical stability.