Temperature-variable apparatus for measuring Barnett field

Area of Science:

• Condensed Matter Physics
• Magnetism
• Experimental Physics

Background:

• The Barnett effect, where mechanical rotation induces magnetization, is a fundamental phenomenon in magnetism.
• Observing the Barnett effect at low temperatures presents experimental challenges due to sensitivity requirements.

Purpose of the Study:

• To develop and validate experimental equipment for observing the Barnett effect at low temperatures.
• To measure the magnetic susceptibility of materials using the Barnett effect.
• To assess the performance of the developed setup using magnetite nanogranules.

Main Methods:

• Utilized a temperature-controlled high-pressure gas system for bidirectional sample rotation.
• Employed a high-sensitivity fluxgate magnetic sensor (picotesla range) to detect stray fields.
• Replaced the rotor with a solenoid coil to estimate magnetic susceptibility.
• Applied a dipole model for Barnett field estimation.
• Conducted measurements on commercial magnetite (Fe3O4) nanogranules.

Main Results:

• Successfully detected Barnett effect-induced stray fields at low temperatures.
• Estimated magnetic susceptibility to be of the same order as the Barnett effect.
• Confirmed the g' factor's accordance with previous room-temperature studies.
• Demonstrated the setup's efficacy for low-temperature magnetic measurements.

Conclusions:

• The developed experimental setup enables the observation and measurement of the Barnett effect at low temperatures.
• The equipment provides a reliable method for characterizing magnetic properties, including susceptibility.
• The findings validate the setup's performance and its potential for further low-temperature magnetism research.