The MagLab is funded by the National Science Foundation and the State of Florida.
The MagLab is funded by the National Science Foundation and the State of Florida.
The AC susceptometer for measurements at ultra-low temperatures consists of a cell totally immersed with the sample in a cell filled with liquid 3He.
The liquid 3He is essential for good thermal contact. The device is a modification of a standard mutual inductance bridge with counter-wound secondary coils with only one containing the sample and one excitation coil as shown below. The components are selected to optimize thermalization and high sensitivity at ultra-low temperatures. Each electrical lead passes through a “sock” of sintered Ag to thermalize the electrons in the electrical leads.
A mutual inductance bridge is used to read the difference in inductance of the two pick-up coils and illustrated below. The transformer is wound form very fine annealed Ag wire (5μm φ) and no ferrite core is used at these temperatures.
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Credit: National MagLab
L. Yin et al., Magnetic Susceptibility Measurements at Ultra-Low Temperatures, J. Low Temp. Phys., 158, 710-715 (2010) Read online.
Last modified on 23 December 2022
