Pressure dependence of the superconducting transition temperature of compressed LaH${}_{10}$

Abstract

Two recent experiments [M. Somayazulu $et$ $al$., Phys. Rev. Lett. $122$, 027001 (2019) and A. P. Drozdov $et$ $al$., Nature $569$, 528 (2019)] reported the discovery of superconductivity in the fcc phase of LaH${}_{10}$ at a critical temperature $T_{\mathrm{c}}$ between 250$\sim$260 K under a pressure of about 170 GPa. However, the dependence of $T_{\mathrm{c}}$ on pressure showed different patterns: i.e., the former experiment observed a continuous increase of $T_{\mathrm{c}}$ up to $\sim$275 K on further increase of pressure to 202 GPa, while the latter one observed an abrupt decrease of $T_{\mathrm{c}}$ with increasing pressure. Here, based on first-principles calculations, we reveal that for the fcc-LaH${}_{10}$ phase, softening of the low-frequency optical phonon modes of H atoms dramatically occurs as pressure decreases, giving rise to a significant increase of the electron-phonon coupling (EPC) constant. Meanwhile, the electronic band structure near the Fermi energy is insensitive to change with respect to pressure. These results indicate that the pressure-dependent phonon softening is unlikely associated with Fermi-surface nesting, but driven by effective screening with the electronic states near the Fermi energy. It is thus demonstrated that the strong variation of EPC with respect to pressure plays a dominant role in the decrease of $T_{\mathrm{c}}$ with increasing pressure, supporting the measurements of Drozdov $et$ $al$.

arXiv comment7 pages, 7 figures

References in corpus (13)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Conventional superconductivity at 203 K at high pressures
• The PseudoDojo: Training and grading a 85 element optimized norm-conserving pseudopotential table
• Superconductivity at 250 K in lanthanum hydride under high pressures
• Evidence for superconductivity above 260 K in lanthanum superhydride at megabar pressures
• EPW: Electron-phonon coupling, transport and superconducting properties using maximally localized Wannier functions
• Observation of the Wigner-Huntington Transition to Solid Metallic Hydrogen
• Hydrogen sulphide at high pressure: a strongly-anharmonic phonon-mediated superconductor
• Quantum Hydrogen-Bond Symmetrization and High-Temperature Superconductivity in Hydrogen Sulfide
• High-Temperature Superconductivity in Alkaline and Rare Earth Polyhydrides at High Pressure: A Theoretical Perspective
• Origin of High-Temperature Superconductivity in Compressed LaH${}_{10}$
• Quantitative analysis of nonadiabatic effects in dense H${}_3$S and PH${}_3$ superconductors
• The Search for Superconductivity in High Pressure Hydrides

Cited by in corpus (11)

• High-throughput discovery of high-temperature conventional superconductors
• Multiband Nature of the Room-Temperature Superconductivity in Compressed LaH${}_{10}$
• Hot Hydride Superconductivity above 550 K
• Stabilization mechanism of clathrate H cages in a room-temperature superconductor LaH${}_{10}$
• Isotope effect in superconducting lanthanum hydride under high compression
• Room-Temperature Superconductivity in Boron-Nitrogen Doped Lanthanum Superhydride
• Electron-phonon coupling and superconductivity in an alkaline earth hydride CaH${}_6$ at high pressures
• Hole-Doping Effect on Superconductivity in Compressed CeH${}_9$ at High Pressure
• High-$T$${}_{\text{C}}$ Superconductivity in Hydrogen Clathrates Mediated by Coulomb Interactions between Hydrogen and Central-Atom Electrons
• Prediction of an unusual trigonal phase of superconducting LaH${}_{10}$ stable from 250 to 425 GPa pressure
• Dynamical Approach to Realize Room-Temperature Superconductivity in LaH${}_{10}$