Liquid 3He thermomechanical effect in regular cylinders.

Area of Science:

• Low-temperature physics
• Quantum fluids
• Nanoscale phenomena

Background:

• The thermomechanical effect in liquid helium-3 is crucial for understanding quantum fluid dynamics.
• Previous studies have not fully explained the behavior of helium-3 in nanoscale confinements.

Purpose of the Study:

• To measure the thermomechanical effect of liquid helium-3 confined in 210 nm Anopore cylinders.
• To investigate the influence of confinement and surface interactions on the thermomechanical effect.

Main Methods:

• Utilized Anopore membranes with precisely sized 210 nm diameter cylinders for liquid helium-3 confinement.
• Measured the pressure difference (deltaP) generated by a temperature difference (deltaT) across the confined liquid.
• Varied the temperature from 0.7 to 12 mK and introduced controlled layers of helium-4.

Main Results:

• Observed a thermomechanical pressure difference of deltaP/deltaT = 25 Pa/mK, independent of temperature.
• This measured value was approximately 100 times the theoretically predicted value.
• The presence of four monolayers of helium-4 significantly reduced the effect by two orders of magnitude.

Conclusions:

• The significantly enhanced thermomechanical effect is attributed to boundary scattering from magnetic helium-3 surface layers.
• Confinement and surface phenomena play a critical role in the behavior of quantum fluids like helium-3.
• These findings necessitate revised theoretical models for thermomechanical effects in confined quantum systems.