ELECTRONIC AND NUCLEAR MAGNETISM IN PTFE AT MILLIKELVIN, MICROKELVIN,AND NANOKELVIN TEMPERATURES

Nuclear magnetic resonance, ac susceptibility and nuclear heat capacit y of two Pt samples with different concentrations of magnetic impuriti es (41ppm and 11ppm), most likely Fe, have been studied in fields of ( 0 +/- 0.05)mT less than or equal to B less than or equal to 248mT and at temperatures of 0.3 mu K less than or equal to T less than or equal to 100mK. No indication for a nuclear magnetic ordering to T-e = 2 mu K (NMR) in 2.5mT and to a nuclear temperature T-n = 0.3 mu K (ac susc eptibility) in (0 +/- 0.05)mT could be detected, and a maximum for the Weiss constant of 0.3 mu K can be estimated. The nuclear heat capacit y data show enhanced values which scale with the impurity concentratio n. We are able to describe this latter data with a spatially varying f ield caused by the magnetic impurities.