Bulk electronic structure of quasicrystals

Area of Science:

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

Background:

• Quasicrystalline solids exhibit unique atomic structures and electronic properties.
• The existence and nature of a pseudogap at the Fermi level in quasicrystals remain a subject of debate.
• Surface-sensitive techniques may not accurately represent the bulk electronic structure.

Purpose of the Study:

• To resolve the controversy surrounding the pseudogap's existence in quasicrystalline solids.
• To investigate the mechanism of quasicrystal formation by examining their electronic structure.
• To compare the electronic properties of different quasicrystalline alloys.

Main Methods:

• Hard x-ray photoemission spectroscopy (HAXPES) was employed.
• The study focused on icosahedral fivefold Al-Pd-Mn and Al-Cu-Fe quasicrystals.
• Results were compared with surface-sensitive low energy photoemission data.

Main Results:

• HAXPES data confirmed the presence of a pseudogap at the Fermi level in both Al-Pd-Mn and Al-Cu-Fe quasicrystals.
• Low energy photoemission failed to detect the pseudogap due to surface metallic phases.
• In Al-Cu-Fe, the pseudogap was fully formed, indicating proximity to a metal-insulator transition.

Conclusions:

• The study provides definitive evidence for the pseudogap in quasicrystals using bulk-sensitive HAXPES.
• The findings clarify the electronic structure and formation mechanism of quasicrystalline solids.
• Al-Cu-Fe quasicrystals are closer to the metal-insulator phase boundary than Al-Pd-Mn.