Ambient-pressure topological superconductivity in Ag4H up to 63 K by metallization of hydrogen

Abstract

Topological superconductors (TSCs) are an ideal platform for realizing Majorana fermions to implement fault-tolerant topological quantum computation. However, the low transition temperature (Tc) of TSCs hinders experimental measurements and practical applications. Here, we propose that metal-bonded perovskite Ag4H is a TSC, characterized by nontrivial topological surface states, a bulk s-wave superconducting gap, and a Tc reaching up to 63 K at ambient pressure. The structural stability, synthesis routes, band topology, and superconductivity are well investigated by first-principles calculations, Wannier interpolation method, effective k · p model, and Migdal-Eliashberg theory. The ambient-pressure phase Ag4H can be realized through kinetic processes of cooling and depressurization from its pressure state. Topological nodal lines and Dirac points with nontrivial Z2 index are identified in Ag4H. Our in-depth analysis reveals an unconventional band inversion mechanism, in which the usually low-lying H-1s band is inverted partially to the Fermi level by intermediate metallization of hydrogen resulting from the metallic bonding of the H sublattice with the Ag matrix. Gap anisotropy is related to Fermi surface nesting and q-dependent electron-phonon coupling. The large H interstitial space, more s/p orbital electrons at the Fermi level, and high H concentration promote high-temperature superconductivity under ambient pressure. Last but not least, Ag4H is the first few-hydrogen metal-bonded intrinsic Eliashberg TSC, exhibiting high Tc near the liquid-nitrogen temperature region. This work may pave a different way to realize topological superconductivity at higher temperature under ambient pressure.

Source-reported materials — not catalogue approval

Similar papers