Superconducting at 298.2 K in lanthanum hydrides

Kwang-Hua, Chu Rainer

doi:10.1016/j.matlet.2020.127743

Cited by 5 publications

(2 citation statements)

References 21 publications

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“…However, density functional calculations suggest that F m3m is unstable to soft phonon distortions primarily involving hydrogen. Such distortions produce infinities in the Migdal-Eliashberg equation and invalidate the BCS approach: the typical theoretical approach is then to ignore the unstable modes [20][21][22][23][24], or to assume the cubic structure is stable and that the unstable mode frequencies can be renormalized [25]. With such approximations, standard BCS calculations of T c via density functional theory and the Migdal-Eliashberg equations then suggest a similarly high value for T c , agreement with experiment typically being within a factor of 2 [26].…”

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confidence: 99%

Competition between superconductivity and molecularization in quantum nuclear behavior of Lanthanum Hydride

Bund¹,

Ackland²

2023

Preprint

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Lanthanum hydride is the superconductor with the highest known critical temperature. It is believed that the superconductivity is of standard BCS-type, with electrons forming Cooper pairs and opening the superconducting band gap. Here we show that the BCS electron pairing is in competition with an alternative pairing: covalent bonding. We show that the covalent pairing is favored at lower pressures, the superconducting cubic phase becomes unstable as pressure is reduced. Previous calculations based on static relaxation neglect three factors, all of which are important in stabilizing the cubic phase. Finite temperature plays a role, and two quantum effects are also importantthe nuclear wavefunction contributes to destablizing the H2 molecules, and the zero-point pressure means that calculated pressures are significantly overestimated by standard methods. We demonstrate these phenomena using Born-Oppenheimer and path-integral molecular dynamics: these give the same qualitative picture, with nuclear quantum effects (NQE) increasing the transition pressure significantly. This competition between molecularization and superconducting gap formation is the fundamental reason why hydride superconductors have so far been found only at high pressure.

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confidence: 99%

Competition between superconductivity and molecularization in quantum nuclear behavior of Lanthanum Hydride

Bund¹,

Ackland²

2023

Preprint

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“…Higher Tc was theoretically proposed in the P-, C-and Si-doped H 3 S [32,33]. In recent years, many new hydrogen-rich materials with different structures were predicted, such as lanthanum, yttrium hydrides [34][35][36] and scandium hydrides [37]. The lanthanum hydride LaH 10 was synthesized and demonstrated to exhibit a Tc of 250-260 K at 170-190 GPa [38][39][40].…”

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confidence: 99%

Enhanced superconductivity in C-S-H compounds at high pressure

Liao,

Zhang,

You

et al. 2021

Preprint

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Recently, the superconducting transition temperature Tc = 287 K has been experimentally obtained in the material composed of carbon, sulfur, and hydrogen under the high pressure of 267 GPa. The material structure is unknown yet, where the carbon and sulfur were added at a molar ratio of 1:1. Here, fixing the molar ratio of C : S = 1:1, we studied several possible C-S-H structures, and found a new stable structure C2S2H4 using the first-principles calculations. The C2S2H4 shows an insulator-to-metal transition and the superconducting ground state at the pressure of 64 GPa, and its Tc can reach 16.5 K at 300 GPa. In addition, we found another stable structure of C2S3H4, whose Tc is 47.4 K at 300 GPa. The calculations show that the added S atom in C2S3H4 breaks part of C-H bonds in C2S2H4, makes the vibration of H atom at a lower frequency, and thus enhances the electro-phonon coupling and Tc. Our results suggest that the molar ratio of C:S lower than 1:1 in the C-S-H systems may be favorable to enhance Tc. This can be useful to figure out the structure of the C-S-H material with room temperature Tc in the recent experiment.

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Coherence length versus transition temperature of hydride-based and room temperature superconductors

Abd‐Shukor

2021

Results in Physics

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Superconducting at 298.2 K in lanthanum hydrides

Cited by 5 publications

References 21 publications

Competition between superconductivity and molecularization in quantum nuclear behavior of Lanthanum Hydride

Competition between superconductivity and molecularization in quantum nuclear behavior of Lanthanum Hydride

Enhanced superconductivity in C-S-H compounds at high pressure

Coherence length versus transition temperature of hydride-based and room temperature superconductors

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Superconducting at 298.2 K in lanthanum hydrides

Cited by 5 publications

References 21 publications

Competition between superconductivity and molecularization in quantum nuclear behavior of Lanthanum Hydride

Competition between superconductivity and molecularization in quantum nuclear behavior of Lanthanum Hydride

Enhanced superconductivity in C-S-H compounds at high pressure

Coherence length versus transition temperature of hydride-based and room temperature superconductors

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Product

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Superconducting at 298.2 K in lanthanum hydrides