3RD-SOUND AND NMR-STUDIES OF HELIUM MIXTURES IN NUCLEPORE

We report measurements of the third sound properties of He-3 - He-4 mi xture films on Nuclepore. Using third sound resonance techniques, we m easure the frequency, damping, amplitude and phase of third sound node s on a mixture film with a fixed coverage of He-4, n(4) = 0.39 Angstro m(-2), as a function of drive power, P-dr, 0.044 less than or equal to P-dr less than or equal to 440 nW, temperature, 40 less than or equal to T less than or equal to 500 mK, and He-3 coverage, 0.01 less than or equal to n(3) less than or equal to 0.06 Angstrom(-2). Near T = 200 mK there is a sharp shift in the difference in phase, delta Phi, betw een the drive voltage fluctuation and the film thickness fluctuation.