Stability and Superconductivity of Ternary Polyhydrides

Fuente: arXiv
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Main Authors: Semenok, Dmitrii V., Zhou, Di, Chen, Wuhao, Kvashnin, Alexander G., Sadakov, Andrey V., Helm, Toni, Ferreira, Pedro N., Heil, Christoph, Pudalov, Vladimir M., Troyan, Ivan A., Struzhkin, Viktor V.
Format: Preprint
Published: 2025
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author Semenok, Dmitrii V.
Zhou, Di
Chen, Wuhao
Kvashnin, Alexander G.
Sadakov, Andrey V.
Helm, Toni
Ferreira, Pedro N.
Heil, Christoph
Pudalov, Vladimir M.
Troyan, Ivan A.
Struzhkin, Viktor V.
author_facet Semenok, Dmitrii V.
Zhou, Di
Chen, Wuhao
Kvashnin, Alexander G.
Sadakov, Andrey V.
Helm, Toni
Ferreira, Pedro N.
Heil, Christoph
Pudalov, Vladimir M.
Troyan, Ivan A.
Struzhkin, Viktor V.
contents We review five years of experimental and theoretical attempts (2020-2025) to enhance the superconducting critical temperature ($\textit{T$_c$}$) of hydrogen-rich compounds by alloying binary superhydrides with additional elements. Despite predictions of higher $\textit{T$_c$}$ in ternary systems such as La-Y-H, La-Ce-H, and Ca-Mg-H, experiments consistently show that the maximum $\textit{T$_c$}$ in disordered ternary superhydrides does not exceed that of the best binary parent hydrides within experimental uncertainty. Instead, alloying primarily stabilizes high-symmetry polyhydride phases at lower pressures, enabling $\textit{T$_c$}$ = 200 K near 110-120 GPa, while also improving vortex pinning and upper critical fields. Magnetic dopants suppress $\textit{T$_c$}$, whereas nonmagnetic additives leave it nearly unchanged, reminiscent of Anderson's theorem. These findings indicate that alloying is unlikely to raise $\textit{T$_c$}$, but can reduce the pressures required to stabilize high-$\textit{T$_c$}$ phases. We propose that fully ordered ternary hydrides, synthesized via controlled hydrogenation of intermetallic precursors, offer a promising route toward this goal. One of the most promising compounds of this kind is the recently discovered LaSc$_2$H$_{24}$.
format Preprint
id arxiv_https___arxiv_org_abs_2509_22877
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Stability and Superconductivity of Ternary Polyhydrides
Semenok, Dmitrii V.
Zhou, Di
Chen, Wuhao
Kvashnin, Alexander G.
Sadakov, Andrey V.
Helm, Toni
Ferreira, Pedro N.
Heil, Christoph
Pudalov, Vladimir M.
Troyan, Ivan A.
Struzhkin, Viktor V.
Superconductivity
We review five years of experimental and theoretical attempts (2020-2025) to enhance the superconducting critical temperature ($\textit{T$_c$}$) of hydrogen-rich compounds by alloying binary superhydrides with additional elements. Despite predictions of higher $\textit{T$_c$}$ in ternary systems such as La-Y-H, La-Ce-H, and Ca-Mg-H, experiments consistently show that the maximum $\textit{T$_c$}$ in disordered ternary superhydrides does not exceed that of the best binary parent hydrides within experimental uncertainty. Instead, alloying primarily stabilizes high-symmetry polyhydride phases at lower pressures, enabling $\textit{T$_c$}$ = 200 K near 110-120 GPa, while also improving vortex pinning and upper critical fields. Magnetic dopants suppress $\textit{T$_c$}$, whereas nonmagnetic additives leave it nearly unchanged, reminiscent of Anderson's theorem. These findings indicate that alloying is unlikely to raise $\textit{T$_c$}$, but can reduce the pressures required to stabilize high-$\textit{T$_c$}$ phases. We propose that fully ordered ternary hydrides, synthesized via controlled hydrogenation of intermetallic precursors, offer a promising route toward this goal. One of the most promising compounds of this kind is the recently discovered LaSc$_2$H$_{24}$.
title Stability and Superconductivity of Ternary Polyhydrides
topic Superconductivity
url https://arxiv.org/abs/2509.22877