Theoretical Predictions of Superconductivity in Alkali Metals under High Pressure

TL;DR

This paper uses band theory and muffin-tin models to predict that certain alkali metals become superconductors under high pressure, with transition temperatures up to 20 K, while sodium remains non-superconducting.

Contribution

It provides theoretical predictions of superconductivity in alkali metals under high pressure, highlighting the role of electron-phonon coupling and specific electronic interactions.

Findings

Lithium, Potassium, Rubidium, Cesium likely superconduct at 5-20 K under high pressure.

Sodium does not become superconducting even at half its original volume.

Electron-phonon coupling increases with pressure, driven by different electronic channels in different elements.

Abstract

We calculated the superconductivity properties of alkali metals under high pressure using the results of band theory and the rigid-muffin-tin theory of Gaspari and Gyorffy. Our results suggest that at high pressures Lithium, Potassium, Rubidium and Cesium would be superconductors with transition temperatures approaching $5-20 K$. Our calculations also suggest that Sodium would not be a superconductor under high pressure even if compressed to less than half of its equilibrium volume. We found that the compression of the lattice strengthens the electron-phonon coupling through a delicately balanced increase of both the electronic and phononic components of this coupling. This increase of the electron-phonon coupling in Li is due to an enhancement of the $s$-$p$ channel of the interaction, while in the heavier elements the $p$-$d$ channel is the dominant component.