Portable DC SQUID based magnetic susceptibility meter

The device is designed as a top-loading system for operation in a storage helium dewar with a 1 1/4" dia neck. Sample temperature is regulated in the range of 4.2-300 K using gaseous helium fed from a helium bath. The sample diameter is up to 4.0 mm, the maximum magnetizing field 0.18 T, the magnetic moment resolution 5/spl times/10/sup -12/ A/spl times/m/sup 2/. The high sensitivity of the instrument makes it possible to investigate the magnetic susceptibility of 1 mm/spl times/1 mm HTc thin films as a function of temperature in a transverse magnetic field of about 10/sup -3/ T. The provisions for measuring the magnetizing field with the help of a Hall sensor enable samples to be cooled down in the fields below 10/sup -5/ T to measure the Meisner effect.< >