Low field DC SQUID nuclear magnetic resonance on single crystal UPt3

A SQUID spectrometer is being used to study high-quality single crystals of UPt3 in low magnetic fields by performing pulsed NMR on Pt-195. The system uses a multiloop DC SQUID with additional positive feedback and operates in flux-locked loop mode from DC to 3 MHz. It has an overall coupled energy sensitivity of 800h and a dead time of similar to5 mus. NMR signals from UPt3 have been observed in both the superconducting mixed state and in the normal state. A bulk platinum marker is used to determine the magnetic field. Measurements of Pt-195 Knight shifts in UPt3 are reported. (C) 2003 Elsevier Science B.V. All rights reserved.