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arXiv · 2504.17998

Why Fe$_3$GaTe$_2$ has higher Curie temperature than Fe$_3$GeTe$_2$?

Bomin Kim·Tumentsereg Ochirkhuyag·Dorj Odkhuu·S. H. Rhim
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Abstract

Physics of Fe$_3$GaTe$_2$ having higher Curie temperature ($T_C$) than Fe$_3$GeTe$_2$ is explored theoretically in the framework of magnetic exchange interactions. Fe$_3$GaTe$_2$ and Fe$_3$GeTe$_2$ are isostructural, with Fe$_3$GaTe$_2$ having one less valence electron and smaller nearest-neighbor exchange coefficients ($J_1$ and $J_2$), challenging the conventional notion that larger $J_1$ or $J_2$ leads to a higher $T_C$. We show that higher order exchange coefficients, $J_3$ or higher, of Fe$_3$GaTe$_2$ are positive whereas those of Fe$_3$GeTe$_2$ are negative. As a consequence, total sum of all possible exchange coefficients in Fe$_3$GaTe$_2$ are larger than Fe$_3$GeTe$_2$, which accounts for higher $T_C$. To validate these findings, $T_C$ are computed using both mean-field theory and Monte Carlo simulation. Indeed, higher-order exchange interactions, when properly accounting for the number of neighbors, confirm the higher $T_C$ of Fe$_3$GaTe$_2$.

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Bomin Kim, Tumentsereg Ochirkhuyag, Dorj Odkhuu, S. H. Rhim. 2025-04-25. Why Fe$_3$GaTe$_2$ has higher Curie temperature than Fe$_3$GeTe$_2$?. https://doi.org/10.1103/g4v8-mrnd

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