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arXiv · 2411.05509

Stability of the first-order character of phase transition in HoCo$_2$

Ajay Kumar·Anis Biswas·Yaroslav Mudryk
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Abstract

HoCo$_2$ exhibits a giant magnetocaloric (MC) effect at its first-order magnetostructural phase transition around 77~K, and understanding the thermodynamic nature of this transition in response to external magnetic fields is crucial for its MC applications. In this study, we present a comprehensive investigation of specific heat and magnetization measurements of HoCo$_2$ under varying magnetic fields. The specific heat measurements qualitatively indicate a transformation from first- to second-order behavior of this phase transition at higher magnetic fields. However, analysis of the power-law dependence of the magnetic entropy change ($\Delta S_{\rm M} \propto$ H$^n$) and the breakdown of universal behavior in the temperature dependence of $\Delta S_{\rm M}$ suggest that the first-order nature remains intact, even up to 7 T. This stability of the first-order nature is further manifested through the distinctive non-linear behavior of modified Arrott plots, with a negative slope in the 6--7 T range.

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Ajay Kumar, Anis Biswas, Yaroslav Mudryk. 2024-11-08. Stability of the first-order character of phase transition in HoCo$_2$. https://doi.org/10.1063/5.0240132

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