Underlying mechanism of charge transfer in Li-doped MgH${}_{16}$ at high pressure

Abstract

A lithium-doped magnesium hydride Li${}_2$MgH${}_{16}$ was recently reported [Y. Sun $et$ $al$., Phys. Rev. Lett. {\bf 123}, 097001 (2019)] to exhibit the highest ever predicted superconducting transition temperature $T_{\mathrm{c}}$ under high pressure. Based on first-principles density-functional theory calculations, we reveal that the Li dopants locating in the pyroclore lattice sites give rise to the excess electrons distributed in interstitial regions. Such loosely bound anionic electrons are easily captured to stabilize a clathrate structure consisting of H cages. This addition of anionic electrons to H cages enhances the H-derived electronic density of states at the Fermi level, thereby leading to a high-$T_{\mathrm{c}}$ superconductivity. We thus propose that the electride nature of Li dopants is an essential ingredient in the charge transfer between Li dopants and H atoms. Our findings offer a deeper understanding of the underlying mechanism of charge transfer in Li${}_2$MgH${}_{16}$ at high pressure.

References in corpus (16)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Conventional superconductivity at 203 K at high pressures
• Superconductivity at 250 K in lanthanum hydride under high pressures
• Evidence for superconductivity above 260 K in lanthanum superhydride at megabar pressures
• Optimization Algorithm for the Generation of ONCV Pseudopotentials
• Synthesis of clathrate cerium superhydride CeH9 below 100 GPa with atomic hydrogen sublattice
• Superconductive "sodalite"-like clathrate calcium hydride at high pressures
• Observation of the Wigner-Huntington Transition to Solid Metallic Hydrogen
• A Perspective on Conventional High-Temperature Superconductors at High Pressure: Methods and Materials
• Superconductivity in Li6P electride
• High-Temperature Superconductivity in Alkaline and Rare Earth Polyhydrides at High Pressure: A Theoretical Perspective
• Interstitial Electronic Localization
• Origin of High-Temperature Superconductivity in Compressed LaH${}_{10}$
• Ternary Inorganic Electrides with mixed bonding
• Hidden Weyl Fermions in Paramagnetic Electride Y${}_2$C
• Stacking-sequence-independent band structure and shear exfoliation of two-dimensional electride materials

Cited by in corpus (1)

• (La,Th)H${}_{10}$: the potential high-$T_c$ superconductors stabilized thermodynamically below 200 GPa