The mean free path for electron conduction in metallic fullerenes

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Electrical resistivity in metals is typically explained by electron scattering and mean free path (l), which is usually larger than atomic distance (d).
• This semi-classical model assumes a minimum mean free path (l > or = d), considered a universal behavior.
• Apparent exceptions in materials like alkali-doped fullerenes and superconductors have raised questions about this universality.

Purpose of the Study:

• To investigate electron conduction in alkali-doped fullerenes using a model calculation.
• To determine if the mean free path (l) can be significantly shorter than the interatomic distance (d) in these materials.
• To explore the validity of the semi-classical model at high temperatures.

Main Methods:

• A model calculation was performed to simulate electron conduction in alkali-doped fullerenes.
• The model specifically considered electron scattering by intramolecular vibrations.
• Analysis focused on the relationship between electrical resistivity, temperature, and electron mean free path.

Main Results:

• The model calculation indicates that at high temperatures, the electrical resistivity implies a mean free path (l) much shorter than the interatomic distance (d) (l << d).
• This contradicts the long-held assumption that l must be greater than or equal to d.
• The findings suggest the breakdown of the semi-classical picture at elevated temperatures.

Conclusions:

• There is no fundamental principle that requires the electron mean free path to be greater than or equal to the interatomic distance.
• The semi-classical model of electron conduction fails at high temperatures in alkali-doped fullerenes.
• Electrons in these systems may not be describable as quasiparticles under such conditions.