A wideband device for measurement of the magnetic properties of materials

We have designed and tested the first version of the wideband SQUID-based universal instrument intended to study magnetic properties of matter within the frequency range 0-1 KHz, in the magnetic fields up to 0.15 T and the temperature range 4.2 - 330 K with the available sample volume ∼ 0.5 cm³. In the present device the spectral density of noise reduced to magnetic moment of the sample was close to 10^-10Axm²/Hz^1/2at frequencies higher than 1 Hz, for the applied field 0.05 T and sample temperature 170 K. An analysis of the noise spectra for various applied magnetic fields has enabled us to indicate a probable main source of this noise and to outline ways to reduce the total noise, hopefully to the SQUID-determined values.