Evidence from Fermi surface analysis for the low-temperature structure of lithium

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Chemistry

Background:

• The low-temperature crystal structure of elemental lithium remains an unresolved problem in condensed matter physics.
• While lithium (Li) typically forms a body-centered cubic lattice at room temperature, experimental evidence suggests a phase transition at lower temperatures.
• The proposed 9R stacking structure has been repeatedly questioned without definitive confirmation.

Purpose of the Study:

• To theoretically analyze the Fermi surface of lithium in various relevant crystal structures.
• To establish the de Haas-van Alphen effect measurements as a diagnostic tool for probing lithium's low-temperature phase diagram.
• To provide a method for determining the low-temperature crystal structure of lithium and other metals at ambient and high pressures.

Main Methods:

• Theoretical analysis of the lithium Fermi surface across different crystal structures.
• Utilizing de Haas-van Alphen effect measurements as a key experimental diagnostic.
• Comparing theoretical Fermi surface predictions with existing low-temperature experimental data.

Main Results:

• The study demonstrates that Fermi surface measurements can effectively diagnose lithium's low-temperature structure.
• Theoretical results indicate that existing experimental data is inconsistent with the proposed 9R phase for lithium's low-temperature structure.
• The proposed Fermi surface analysis method offers advantages over traditional X-ray and neutron diffraction techniques.

Conclusions:

• The Fermi surface analysis provides a robust method for elucidating low-temperature metal structures.
• The 9R phase is unlikely to be the correct low-temperature structure for elemental lithium based on current experimental data.
• This approach has the potential to resolve long-standing structural mysteries in elemental metals.