Structural, magnetic, and magnetocaloric properties of (Hf0.83Ta0.17)Fe2+x materials

We have investigated the sensitivity of structural, magnetic, and magnetocaloric properties of (Hf0.83Ta0.17)Fe2+x alloys (x=−0.18, −0.09, −0.02, 0.00, 0.09, 0.26) to Fe content. As-cast samples for all x consist essentially exclusively of hexagonal MgZn2-type material. Via magnetization and differential scanning calorimetry measurements we find that all the alloys except x=0.26 feature both a ferromagnetic→antiferromagnetic (FM→AFM) transition at temperature T0 and a Néel transition. The most abrupt FM→AFM transition occurs in the x=−0.02 material which also exhibits the lowest T0 and largest low-temperature moment. We report a magnetocaloric property, the field-induced entropy change ΔS, for the x=0.00 and x=±0.09 alloys.