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

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 ($T_{\mathrm{C}}$) 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 $T_{\mathrm{C}}(x)$ 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 $T_{\mathrm{C}}$.

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Cited by in corpus (4)

• Influence of structural disorder on magnetic properties and electronic structure of YCo${}_2$
• Predicting the Curie temperature of magnetic materials with automated calculations across chemistries and structures
• Monte Carlo calculations of Curie temperatures of Y${}_{1-x}$Gd${}_x$(Fe${}_{1-y}$Co${}_y$)${}_2$ pseudobinary system
• Electronic specific heat coefficient and magnetic properties of Y(Fe${}_{1-x}$Co${}_x$)${}_2$ Laves phases: a combined experimental and first-principles study