Superconductivity in Bismuth. A New Look at an Old Problem

Area of Science:

• Condensed Matter Physics
• Materials Science
• Superconductivity

Background:

• Superconductivity in bismuth is influenced by its atomic structure.
• Understanding the interplay between electronic, vibrational, and topological properties is crucial for predicting superconductivity.

Purpose of the Study:

• To investigate the relationship between atomic topology, vibrational and electronic properties, and superconductivity in amorphous bismuth.
• To compare the properties of amorphous bismuth (a-Bi) with crystalline bismuth (x-Bi).

Main Methods:

• Computer generation of a 216-atom amorphous bismuth structure (a-Bi216) using an undermelt-quench approach.
• Calculation of pair distribution function, electronic density of states (eDOS), and vibrational density of states (vDOS).
• Estimation of superconducting transition temperature using BCS theory and McMillan's formula to determine electron-phonon coupling (λ).

Main Results:

• The pair distribution function of a-Bi216 closely matches experimental data.
• Amorphous bismuth shows approximately 4 times higher electronic density of states at the Fermi energy compared to crystalline bismuth.
• While the energy range of vDOS is similar, its shape differs significantly between amorphous and crystalline bismuth.
• Electron-phonon coupling (λ) is substantially higher in amorphous bismuth (λa = 2.46) than in crystalline bismuth (λc = 0.24).

Conclusions:

• Superconductivity in amorphous bismuth is enhanced compared to crystalline bismuth.
• The enhancement is attributed to higher electron-phonon coupling (λ) and increased electronic density of states at the Fermi energy in the amorphous structure.