Near-field heat transfer in a scanning thermal microscope

Area of Science:

• Physics
• Materials Science
• Nanotechnology

Background:

• Near-field heat transfer is crucial for understanding thermal transport at the nanoscale.
• Existing theories, like fluctuating electrodynamics, predict heat transfer based on macroscopic dielectric properties.
• Scanning thermal microscopy requires accurate interpretation of near-field interactions.

Purpose of the Study:

• To measure near-field heat transfer between a thermal profiler tip and planar surfaces.
• To investigate deviations from fluctuating electrodynamics predictions at small tip-sample distances.
• To explore the role of material-dependent length scales in nanoscale heat transfer.

Main Methods:

• Utilizing ultrahigh vacuum conditions for precise measurements.
• Employing a thermal profiler to measure heat transfer.
• Analyzing data at tip-sample distances below 10⁻⁸ meters.

Main Results:

• Observed significant differences between experimental results and fluctuating electrodynamics predictions.
• Identified deviations becoming prominent at tip-sample distances below 10⁻⁸ m.
• Data suggests a material-dependent small length scale where macroscopic dielectric descriptions fail.

Conclusions:

• The macroscopic description of dielectric properties is inadequate at very small length scales.
• A heuristic model incorporating this small length scale shows good agreement with experimental data.
• These findings are vital for accurate quantitative interpretation of scanning thermal microscopy signals.