A high resolution dilatometer using optical fiber interferometer

Area of Science:

• Condensed Matter Physics
• Materials Science
• Cryogenic Engineering

Background:

• Accurate measurement of thermal expansion is crucial for understanding phase transitions in materials.
• Existing dilatometry techniques often lack the resolution or sensitivity required for studying thin or fragile samples.

Purpose of the Study:

• To introduce a novel, high-performance differential dilatometer capable of cryogenic operation.
• To achieve ultra-high resolution in measuring length changes (δL/L) and temperature.

Main Methods:

• Utilizing an all-fiber Michelson interferometer for precise, contactless length change detection.
• Employing an in situ thermometer for accurate sample temperature monitoring.
• Operating the system at cryogenic temperatures to study phase transitions.

Main Results:

• Achieved a resolution of 10-10 in relative length change (δL/L).
• Demonstrated sub-picometer length change resolution and millikelvin temperature resolution.
• Successfully measured the linear thermal expansion coefficient near the antiferromagnetic transition of BaFe2As2.

Conclusions:

• The developed dilatometer is a powerful tool for studying phase transitions in condensed matter physics.
• Offers significant advantages for fragile materials (sub-100 μm thickness) due to high resolution and contactless nature.
• The prototype design allows for further improvements and integration with synchronous measurements.