Quantum Crystal Structure in the 250 K Superconducting Lanthanum Hydride - Spectroscopie des nouveaux états quantiques Accéder directement au contenu
Pré-Publication, Document De Travail Année : 2019

Quantum Crystal Structure in the 250 K Superconducting Lanthanum Hydride

Francesco Belli
  • Fonction : Auteur
Lorenzo Monacelli
  • Fonction : Auteur
Antonio Sanna
  • Fonction : Auteur
Takashi Koretsune
  • Fonction : Auteur
Terumasa Tadano
  • Fonction : Auteur
Raffaello Bianco
Matteo Calandra
Ryotaro Arita
  • Fonction : Auteur

Résumé

The discovery of superconductivity at 200 K in the hydrogen sulfide system at large pressures [1] was a clear demonstration that hydrogen-rich materials can be high-temperature superconductors. The recent synthesis of LaH$_{10}$ with a superconducting critical temperature (T$_{\text{c}}$) of 250 K [2,3] places these materials at the verge of reaching the long-dreamed room-temperature superconductivity. Electrical and x-ray diffraction measurements determined a weakly pressure-dependent T$_{\text{c}}$ for LaH$_{10}$ between 137 and 218 gigapascals in a structure with a face-centered cubic (fcc) arrangement of La atoms [3]. Here we show that quantum atomic fluctuations stabilize in all this pressure range a high-symmetry Fm-3m crystal structure consistent with experiments, which has a colossal electron-phonon coupling of $\lambda\sim3.5$. Even if ab initio classical calculations neglecting quantum atomic vibrations predict this structure to distort below 230 GPa yielding a complex energy landscape with many local minima, the inclusion of quantum effects simplifies the energy landscape evidencing the Fm-3m as the true ground state. The agreement between the calculated and experimental T$_{\text{c}}$ values further supports this phase as responsible for the 250 K superconductivity. The relevance of quantum fluctuations in the energy landscape found here questions many of the crystal structure predictions made for hydrides within a classical approach that at the moment guide the experimental quest for room-temperature superconductivity [4,5,6]. Furthermore, quantum effects reveal crucial to sustain solids with extraordinary electron-phonon coupling that may otherwise be unstable [7].

Dates et versions

hal-02358073 , version 1 (11-11-2019)

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Citer

Ion Errea, Francesco Belli, Lorenzo Monacelli, Antonio Sanna, Takashi Koretsune, et al.. Quantum Crystal Structure in the 250 K Superconducting Lanthanum Hydride. 2019. ⟨hal-02358073⟩
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