Fermi surface deformation in lithium under high pressure

Abstract

Since recent both theoretical and experimental results have proved that the simple behaviour light alkaline metals present at equilibrium breaks when high pressures are applied, they have become an important object of study in Condensed Matter Physics. In this work, we present an analysis of the pressure-induced Fermi surface (FS) deformation in lithium with increasing pressure. The spheroidal FS at equilibrium becomes highly anisotropic with increasing pressure, so that at around 8 GPa touches the FS explaining the observed bcc→fcc transition via a Hume–Rothery effect, and at around 30 GPa develops increasing cooper-like necks and an extended nesting which could be the origin of the complex phase transitions produced via a phonon instability. On the other hand, these distortions in the FS is expected to enhance the electronic susceptibility response function and increase the electron–phonon interaction with pressure, which might also allow a better understanding of the observed superconducting transition in lithium at around the same pressure range.