Prediction of superconductivity in bilayer borophenes.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Superconductivity

Background:

• Single-layer borophene superconductivity is limited by substrate interactions.
• Bilayer (BL) borophenes offer a pathway to stabilized superconductivity.
• Two stable BL structures, BL-B8 and BL-B30, were identified.

Purpose of the Study:

• Investigate the stability, electronic, and phonon properties of BL-B8 and BL-B30.
• Explore the potential for superconductivity in these stabilized borophene structures.
• Understand the role of lattice vibrations in borophene superconductivity.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Bardeen-Cooper-Schrieffer (BCS) theory framework.
• Systematic analysis of electron structures and phonon properties.

Main Results:

• BL-B8 and BL-B30 exhibit metallic characteristics.
• Intrinsic superconductivity observed with transition temperatures of 11.9 K (BL-B8) and 4.9 K (BL-B30).
• Low-frequency out-of-plane vibrations significantly contribute to superconductivity; a Kohn anomaly in BL-B8 enhances electron-phonon coupling.

Conclusions:

• Stabilized bilayer borophenes demonstrate intrinsic superconducting properties.
• Lattice vibrations, particularly low-frequency modes, are crucial for superconductivity in these materials.
• Findings offer guidance for experimental realization and expand the family of two-dimensional superconductors.