Low-temperature measurement system based on a closed-cycle refrigerator

We have built a new torque magnetometer with a closed-cycle helium refrigerator. The temperature can be lowered down to 1.5 K by pumping liquefied helium in sample space. The temperature can be stabilized within ±0.01 K by using the two-independent PID loops. A piezoresistor bridge configured with a silicon cantilever surface is used to detect a torque. A transeverse magnetic field, which is fabricated by the several pieces of the permanent magnets, can produce a field up to 10 kG in any direction. The system has complete control from a computer by coding a LabVIEW. We have demonstrated the torque curves of a single crystal YBa2Cu4O8 successfully even at 1.6 K