Superconducting magnetometer for high resolution susceptibility measurements

We have developed a superconducting susceptometer operating in temperature range up to 230°K. The instrument is capable of routine susceptibility measurements on frozen solutions and suspensions, powders, crystals; a single helium fill up, lasting about 8 hours, allows about 50 susceptibility measurements at various sample temperatures. Sensitivity is 6 × 10^-11e.m.u./cc for a sample volume of 0.5 cc and is independent of temperature. The overall accuracy of the instrument for sample temperatures upto 230°K is 3 × 10^-9e.m.u./cc, temperature independent, in a typical applied field of 20 gauss.