Evidence of Phonon‐Mediated Superconductivity in LaH10 at High Pressure

• Published in: Annalen der Physik Vol. 533; no. 3
• Main Authors: Durajski, Artur P., Wang, Chongze, Li, Yinwei, Szczȩśniak, Radosław, Cho, Jun‐Hyung
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01-03-2021
• Subjects: 74.25.Bt; 74.62.Fj; Clathrates; Critical field (superconductivity); density‐functional theory calculations; Energy gap; Isotope effect; Lanthanum; lanthanum hydride; pacs number, 74.20.Fg; Phonons; Superconductivity; Thermodynamic properties
• ISSN: 0003-3804; 1521-3889
• DOI: 10.1002/andp.202000518

Motivated by the recent experimental discovery of the high‐critical‐temperature superconductor LaH10 (250–260 K at high pressures 170–190 GPa), the influence of H isotope substitution on the phonon spectra, electron–phonon interactions, and thermodynamic properties of superconducting LaH10−xDx (x=0,2,5,8,10) at 250 GPa are studied. On the basis of first‐principles calculations, it is found that all investigated systems are dynamically stable in a clathrate structure with space group Fm3¯m and exhibit high superconducting critical temperatures Tc ranging from 169 to 234 K. The dominant role of hydrogen in enhancing Tc is examined by numerically solving the Eliashberg equations. The estimated critical temperature, superconducting energy gap, specific heat, and thermodynamic critical field demonstrate that the underlying mechanism of superconductivity in lanthanum hydride is conventional electron–phonon coupling, which manifests itself in terms of isotope effect.
Hydrogen and hydrogen‐rich materials are currently of great interest for obtaining superconductivity at room temperature. A comprehensive study of the electronic structure, electron–phonon interaction, isotope effect, and thermodynamic properties of compressed LaH10−xDx systems confirms the experimental data and proves the conventional electron–phonon mechanism of high‐temperature superconductivity in lanthanum hydrides.