Effect of Dy substitution in the giant magnetocaloric properties of HoB2.

Recently, a massive magnetocaloric effect near the liquefaction temperature of hydrogen has been reported in the ferromagnetic material HoB2. Here we investigate the effects of Dy substitution in the magnetocaloric properties of Ho1-x Dy x B2 alloys (x = 0, 0.3, 0.5, 0.7, 1.0). We find that the Curie temperature (T C) gradually increases upon Dy substitution, while the magnitude of the magnetic entropy change |ΔS M| and adiabatic temperature change ΔT ad showed a gradual decrease. On the other hand, due to the presence of successive transitions in these alloys, the peak height of the above magnetocaloric properties tends to be kept in a wide temperature range, leading to a relatively robust figure of merit in a wide temperature span. These alloys could be interesting candidates for magnetic refrigeration in the temperature range of 10-60 K.