Plasmons in Li under compression.

Area of Science:

• Condensed matter physics
• Materials science
• Solid-state physics

Background:

• Understanding material properties under extreme conditions is crucial for developing new technologies.
• Lithium's unique electronic structure makes its high-pressure behavior a subject of significant scientific interest.

Purpose of the Study:

• To investigate the high-pressure behavior of plasmons in polycrystalline lithium.
• To correlate changes in plasmon properties with structural phase transitions and electronic band structure modifications.

Main Methods:

• Inelastic X-ray scattering (IXS) was employed to probe plasmon dynamics.
• Ab initio calculations were performed to complement experimental findings and elucidate underlying mechanisms.
• Experiments were conducted at room temperature up to 15 GPa.

Main Results:

• Plasmon energy ([Formula: see text]) showed a direct correlation with decreasing atomic volume ([Formula: see text]).
• A distinct discontinuity in the plasmon energy slope was observed at the body-centered cubic (bcc) to face-centered cubic (fcc) structural phase transition, indicating a change in electronic band structure.
• The plasmon peak width ([Formula: see text]) versus momentum transfer (q) exhibited a parabola-like shape for bcc-Li below 6.5 GPa, transitioning to a convex shape for fcc-Li above 8.4 GPa.

Conclusions:

• The study reveals significant changes in lithium's plasmonic properties under high pressure, directly linked to its structural phase transitions.
• The observed discontinuity in plasmon energy slope serves as a sensitive indicator of electronic structure modifications during the bcc-fcc phase change.
• The distinct evolution of plasmon peak width with pressure highlights pressure-induced alterations in electron dynamics and scattering mechanisms in lithium.