Low field DC SQUID nuclear magnetic resonance on single crystal UPt3

Abstract A SQUID spectrometer is being used to study high-quality single crystals of UPt 3 in low magnetic fields by performing pulsed NMR on 195 Pt. 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 800 h and a dead time of ∼5 μs. NMR signals from UPt 3 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 195 Pt Knight shifts in UPt 3 are reported.