Magnetotransport Apparatus

The transport facility is capable of observing the resistive transition to superconductivity of the sample in temperature under various applied current and applied magnetic field conditions. A KEITHLEY 224 programmable current source supplies a constant DC current of as high as 99 mA through the sample. A KEITHLEY 2000 multimeter interfaced to the computer measures the corresponding voltage. A CRYODYNE Cryocooler, which uses Helium as a refrigerant, is employed as a source of cryogenic temperatures of as low as 8K under vacuum conditions of at least 5x10-2 torr. A LAKESHORE 331 Temperature Controller provides the temperature data to the computer. Also, the temperature controller is adequately equipped with a heater for experiments requiring isothermal conditions such as low-temperature I-V data gathering. A LAKESHORE 647magnet power supply sets up an external DC magnetic field along the c-axis of the sample, and can reach field magnitudes of up to 1.25T, calibrated to the radius of the cold head, where the sample is located.