A Measure Of The Exchange Of A Weak Signal Cryostat Developed And Its Performance Testing

The present report describes a cryostat specially designed for multi-purpose ac measurements over the temperature range from -1.4K to 300K. Special efforts have been made for decreasing the heat leak from both room temperature and surrounding helium to the pumped helium which the sample holder is thermally contacted with. The sample can be kept at 1.4K for more than 20 hours with the measuring power of 0.15mW. The combination of a modulation field of -0.18T and a dc background field of 8T makes it possible to realize double-ac measurement of both magnetoresistanceand Hall coefficient R_H . A test experiment of the Hall coefficient of Co films shows that the measurement accuracy can be reached down to 0.5nV.