Effect of Dy substitution in the giant magnetocaloric properties of HoB₂

ABSTRACT

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 Ho_1-xDy_xB₂ 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.

Graphical abstract

KEYWORDS:

• Magnetic refrigeration
• magnetocaloric effect
• adiabatic temperature change

CLASSIFICATION:

• 203 Magnetics / Spintronics / Superconductors
• Magnetocaloric Materials

Acknowledgments

We acknowledge fruitful discussions with Mohammed Elmassalami and Akiko T. Saito. This work was partly supported by the JST-Mirai Program “Development of advanced hydrogen liquefaction system by using magnetic refrigeration technology”, the JSPS KAKENHI, and the JST-CREST. P.B. Castro acknowledges the scholarship support from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.

Disclosure statement

The authors declare no conflict of interest.

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Funding

This work was supported by the JST-Mirai Program (Grant No. JPMJMI18A3), JSPS KAKENHI (Grant Nos. 19H02177, 20K05070), JST CREST (Grant No. JPMJCR20Q4).