Construction and calibration of a 12 T pulsed magnet integrated with a 4 K closed-cycle refrigerator

A low cost 12 T pulsed magnet system has been integrated with a closed-cycle helium refrigerator for performing magnetotransport measurements. Minimal delay between pulses and ac current excitation with software lock-in to reduce noise enables quick but accurate measurements to be performed at temperatures of 4-300 K up to 12 T. An additional pulsed magnet operating with a liquid nitrogen cryostat extends the range up to 19 T. The instrument has been calibrated against a commercial superconducting magnet by comparing quantum Hall effect data in a p-channel SiGe/Si heterostructure, and common issues arising out of pulsed magnet usage have been addressed. The versatility of the system is demonstrated through magnetotransport measurements in a variety of samples such as heterostructures, narrow gap semiconductors, and those exhibiting giant magnetoresistance. (c) 2007 American Institute of Physics.