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Rev. Sci. Instrum. (2004) 75(8) To be published.
A low-temperature high-sensitivity torsion balance magnetometer with in situ stator adjustment
A.J. Matthews, A. Usher and C.D.H. Williams
School of Physics, University of Exeter, Exeter, EX4 4QL (UK).
(Submitted January 2004)
Torsion balance magnetometry can be used as a versatile probe of two-dimensional electron systems. We have developed a highly sensitive magnetometer, utilising capacitive proximity detection of the rotor position, for use at temperatures below 10 mK. The instrument incorporates two piezo-electric linear motors to enable the stator positions to be adjusted in situ at base temperature. The magnetometer responsivity is inversely proportional to the square of the rotor-stator separation and the novel linear motor technique, accompanied by effective vibration isolation and optimised capacitance bridge electronics, achieves a resolution 6.5×10-12 N m Hz-1/2.