A thermodynamic model to predict electron mobility in superfluid helium.

Area of Science:

• Condensed Matter Physics
• Quantum Fluids
• Low-Temperature Physics

Background:

• Electron mobility in superfluid helium is crucial for understanding quantum fluid properties.
• Existing models often lack comprehensive descriptions across various temperature and pressure conditions.

Purpose of the Study:

• To develop and validate a thermodynamic model for electron mobility in superfluid helium from 0.1 to 2.2 K.
• To identify and characterize distinct regimes of electron mobility based on temperature and scattering mechanisms.

Main Methods:

• Utilized a van der Waals-type thermodynamic equation of state to model free volume.
• Calibrated the model against known electron mobility data and validated against literature values.
• Introduced a temperature and density dependent Millikan-Cunningham factor for non-continuum behavior.

Main Results:

• Identified four electron mobility regimes: Landau critical velocity, phonon-limited, roton gas-limited, and roton continuum-limited.
• The model accurately reproduced literature values within 10% accuracy.
• Predicted larger hydrodynamic electron bubble radii compared to DFT calculations, attributed to viscosity variations.

Conclusions:

• The study provides a unified model for electron mobility in superfluid helium across a wide temperature range.
• Discrepancies between model predictions and DFT suggest complex interactions at the electron-solvation interface.
• The findings enhance understanding of charge transport in quantum fluids.