A-15 type superconducting hydride $La_4H_{23}$: Nanograined structure with low strain, strong electron-phonon interaction, and moderate level of nonadiabaticity

E. F. Talantsev; V. V. Chistyakov

doi:10.1088/1361-6668/ad637e

paper

A-15 type superconducting hydride $L a_{4} H_{23}$ : Nanograined structure with low strain, strong electron-phonon interaction, and moderate level of nonadiabaticity

arXiv:2402.19384 · doi:10.1088/1361-6668/ad637e

Abstract

For seven decades by A-15 superconductors we meant metallic $A_{3} B$ alloys (where A is a transition metal, and B is groups IIIB and IVB element) discovered by Hardy and Hulm (Phys. Rev. 89, 884 (1953)). Nb3Ge exhibited the highest superconducting transition temperature, $T_{c} = 23 K$ , among these alloys. One of these alloys, $N b_{3} S n$ , is primary material in modern applied superconductivity. Recently Guo et al (arXiv:2307.13067) extended the family of superconductors where the metallic ions arranged in the beta tungsten (A-15) sublattice by observation of $T_{c, z er o} = 81 K$ in $L a_{4} H_{23}$ phase compressed at $P = 118 GP a$ . Despite the $L a_{4} H_{23}$ has much lower $T_{c}$ in comparison with near-room-temperature superconducting $L a H_{10}$ phase ( $T_{c, z er o} = 250 K$ at $P = 200 GP a$ ) discovered by Drozdov et al (Nature 569, 531 (2019)), the $L a_{4} H_{23}$ holds the record high $T_{c}$ within A-15 family. Cross et al (Phys. Rev. B 109, L020503 (2024)) confirmed the high-temperature superconductivity in the compressed $L a_{4} H_{23}$ . In this paper, we analyzed available experimental data measured in $L a_{4} H_{23}$ and found that this superconductor exhibits nanograined structure, 5.5 nm < D < 35 nm, low crystalline strain < 0.003, high electron-phonon coupling constant, 1.5 < $λ_{e - p h}$ < 2.55, and moderate level of the nonadiabaticity $Θ_{D} / T_{F}$ . We found that derived $Θ_{D} / T_{F}$ and $T_{c} / T_{F}$ values for the $L a_{4} H_{23}$ phase are similar to the ones in cuprates, pnictides, and near-room-temperature superconductors $H_{3} S$ and $L a H_{10}$ , which implies that the $L a_{4} H_{23}$ phase falls to unconventional superconductors band in the Uemura plot.

43 pages, 12 figures + 3 figures in Supplementary Materials

A-15 type superconducting hydride $L a_{4} H_{23}$ : Nanograined structure with low strain, strong electron-phonon interaction, and moderate level of nonadiabaticity

Abstract

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A-15 type superconducting hydride La4​H23​: Nanograined structure with low strain, strong electron-phonon interaction, and moderate level of nonadiabaticity

Abstract

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Cited by in corpus (2)

A-15 type superconducting hydride $L a_{4} H_{23}$ : Nanograined structure with low strain, strong electron-phonon interaction, and moderate level of nonadiabaticity