Absence of sizable superconductivity in hydrogen boride: A first principles study

TL;DR

This study uses first-principles calculations to investigate hydrogen boride monolayer's electronic and superconducting properties, finding it lacks sizable superconductivity due to weak electron-phonon interactions and hydrogen states at the Fermi level.

Contribution

It provides a detailed first-principles analysis showing hydrogen boride's limited superconductivity and the importance of hydrogen states at the Fermi level for high Tc in hydrogenated monolayers.

Findings

Hydrogen boride does not exhibit sizable superconductivity.

Hydrogen content weakens electron-phonon interactions.

Doping does not significantly enhance Tc.

Abstract

The recently synthesized hydrogen boride monolayer in the Cmmm phase is a promising super-conductor due to its similarity to MgB2 and the large hydrogen content in its structure. Making use of first-principles calculations based on density functional theory, we study its electronic, vibrational,and superconducting properties and conclude that, despite the expectations, hydrogen boride does not have a sizable superconducting critical temperature. The presence of hydrogen in the system alters the boron-boron bonding, weakening the electron-phonon interaction. We have studied the effect of enhancing the critical temperature by doping the system, but the inclusion of electrons or holes reveals ineffective. We attribute the small critical temperature of this system to the vanishing hydrogen character of the states at the Fermi level, which are dominated by boron p states. Our results determine that a large proportion of hydrogen-like states are needed at the Fermi level to attain a large superconducting critical temperature in hydrogenated monolayers.