Radio-frequency susceptibility apparatus for measuring small superconducting samples

Abstract
A radio-frequency magnetic susceptibility apparatus is described, which is capable of measuring the superconducting transition temperature of individual samples with volumes as small as 2×10−8 cm3 (mass ≂0.1 μg) with a signal-to-noise ratio of 20. The system uses phase-sensitive detection and operates between 1 and 10 MHz. Measurements in large dc magnetic fields ∼150 kG are also possible. Detailed information concerning construction and operation is provided.