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

Abstract

The recently synthesized hydrogen boride monolayer in the Cmmm phase is a promising superconductor 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 hint at a possible relation between the presence of a large proportion of hydrogen-like states at the Fermi level and a large superconducting critical temperature in hydrogenated monolayers.

Quantifying the Nonadiabaticity Strength Constant in Recently Discovered Highly Compressed Superconductors

“…First-principles calculations [12][13][14][15][16][17][18][19][20][21][70][71][72][73][74][75][76][77][78][79] are essential tools in the quest for roomtemperature superconductivity (they were used [76] to explain the experimental results [80] for one of the most difficult-to-explain hydride cases, AlH 3 ), and the primary calculated parameter in these calculations is the transition temperature, T c . In addition, another difficult-to-explain hydride should be mentioned, which is LiPdH x [46].…”

Influence of Lifshitz Transition on the Intrinsic Resistivity of Cu2N Monolayer

“…When the Fermi level is shifted to 0.2 eV, the simplest Fermi surface consisting only of b1(−) bands appears. For the variations in Fermi level induced by carrier doping, the four Fermi levels from low to high correspond to carrier doping concentrations of −2.58 × 10 14 cm –2 , 0 cm –2 , 1.89 × 10 14 cm –2 , and 2.79 × 10 14 cm –2 , which are accessible by state-of-the-art experimental methods, such as ionic liquid gating technology. − Here, we simulate the band structure under carrier doping by introducing a metal gate electrode below the Cu 2 N monolayer, , allowing carrier transfer between the Cu 2 N monolayer and the electrode. We find that in such a setup the band structure of the Cu 2 N monolayer remains almost unchanged when the Fermi level is shifted to the positions considered in our work due to electric doping (Figure S1).…”