Curie temperature study of the Y(Fe$_{1-x}$Co$_x$)$_2$ and Zr(Fe$_{1-x}$Co$_x$)$_2$ systems using mean-field theory and Monte Carlo method

Bartosz Wasilewski; Wojciech Marciniak; Mirosław Werwiński

doi:10.1088/1361-6463/aab75b

paper

Curie temperature study of the Y(Fe $_{1 - x}$ Co $_{x}$ ) $_{2}$ and Zr(Fe $_{1 - x}$ Co $_{x}$ ) $_{2}$ systems using mean-field theory and Monte Carlo method

arXiv:2503.14199 · doi:10.1088/1361-6463/aab75b

Abstract

The cubic Laves phases including YFe $_{2}$ , YCo $_{2}$ , ZrFe $_{2}$ , and ZrCo $_{2}$ are considered as promising candidates for application in hydrogen storage and magnetic refrigeration. While YFe $_{2}$ and ZrFe $_{2}$ are ferromagnets, alloying with Co decreases magnetic moments and Curie temperatures ( $T_{C}$ ) of pseudobinary Zr(Fe $_{1 - x}$ Co $_{x}$ ) $_{2}$ and Y(Fe $_{1 - x}$ Co $_{x}$ ) $_{2}$ systems, leading to the paramagnetic states of YCo $_{2}$ and ZrCo $_{2}$ . The following study focus on the investigation of Curie temperature of the Y(Fe $_{1 - x}$ Co $_{x}$ ) $_{2}$ and Zr(Fe $_{1 - x}$ Co $_{x}$ ) $_{2}$ system from first principles. To do it, the Monte Carlo (MC) simulations and the mean field theory (MFT) based on the disordered local moments (DLM) calculations are used. The DLM-MFT results agree qualitatively with the experiment and preserve the characteristic features of $T_{C} (x)$ dependencies for both Y(Fe $_{1 - x}$ Co $_{x}$ ) $_{2}$ and Zr(Fe $_{1 - x}$ Co $_{x}$ ) $_{2}$ . However, we have encountered complications in the Co-rich regions due to failure of the local density approximation (LDA) in describing the Co magnetic moment in the DLM state. The analysis of Fe-Fe exchange couplings for YFe $_{2}$ and ZrFe $_{2}$ phases indicates that the nearest-neighbor interactions play the main role in the formation of $T_{C}$ .

Curie temperature study of the Y(Fe $_{1 - x}$ Co $_{x}$ ) $_{2}$ and Zr(Fe $_{1 - x}$ Co $_{x}$ ) $_{2}$ systems using mean-field theory and Monte Carlo method

Abstract

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Curie temperature study of the Y(Fe1−x​Cox​)2​ and Zr(Fe1−x​Cox​)2​ systems using mean-field theory and Monte Carlo method

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Curie temperature study of the Y(Fe $_{1 - x}$ Co $_{x}$ ) $_{2}$ and Zr(Fe $_{1 - x}$ Co $_{x}$ ) $_{2}$ systems using mean-field theory and Monte Carlo method