Pressure Dependence of the Longitudinal Resonance Frequency of 3He Superfluid Phases in Aerogel

Pulsed NMR measurements have been performed on superfluid 3He within a 98% porosity aerogel over a pressure range of 8 to 26 bar. The aerogel sample is homogeneous and isotropic as indicated by in situ optical birefringence and, on similarly prepared samples, using SAXS characterization. Two different superfluid phases are observed at low temperature. The two phases are identified as the same as the A and B-phases in pure 3He, from tip angle measurement and the NMR equations of Leggett. The pressure and temperature dependence of the longitudinal resonance frequency of each phase is reported in this article.