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Texture transitions in superfluid 3 He-A are produced by a moving bellows system controlling mass flow. These texture changes are caused by the competition of magnetic, flow, and gradient energies. We have located the boundary of a region of stability with v* s II / IIH. This boundary may be related to theoretical predictions of a transition to helical textures, but there is substantial disagreement with the theory over the maximum magnitude of the superfluid velocity in what we interpret as uniform textures. PACS numbers: 67.50.Fi, 43.35. + d, 47.20. + m Textures in superfluid 3 He are a striking manifestation of the symmetry of the order parameter. To date, however, only a few relatively simple textures have been studied. We report here the first measurements on nontrivial dynamic textures in the A phase which are produced in a controlled fashion and which exhibit great sensitivity to the effect of superfluid flow. We have located a boundary between the uniform texture and a complex texture by varying the magnetic field while maintaining a constant mass flow.

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A system has been developed to directly observe NMR free induction signals at very low frequencies. We use a nonresonant pickup arrangement with a commercial dc SQUID to monitor the precessing magnetization in a 0.5-50-kHz range of Larmor frequencies. A relocking interval for the SQUID's flux locked loop presently sets our pulse recovery around 20-30 J.ls throughout this frequency range. The noise for this system is less than 1.5 times that recorded for the SQUID with shorted input tenninals.

We study the magnetic properties of 3He confined in a grafoil substrate with the static applied field more than two orders of magnitude less than in prior experiments. In this low-field regime, we observe new modes in the nuclear magnetic resonance spectrum that arise for T < 1 mK. We interpret these as the collective modes of ferromagnetically ordered domains in the 3He boundary layers. The frequency shifts of these modes suggest that the domains reorient as the static field is varied. From the size of the frequency shifts, we also conclude that 3He dipole fields can only partially account for the system anisotropy energy.

We present measurements of the intrinsic thermal boundary resistance across the interface between PrNi5 and 'He. Over the entire temperature range studied (2-15 mK), the boundary resistance varies as T . At low magnetic fields (0-40 mT) the boundary resistance decreases significantly with increasing field. We discuss the heat capacity of PrNi5 implied from the measured thermal time constants. We include a comparison between these results and several other boundary-resistance measurements.Although thermal contact between 3He and metals at 42 4752

We have measured the steady state thermal conduction between. 3He and PrNi5. The PrNi5 sample consisted of 40 µm particles, which were sufficiently large so that the 3He quasiparticle mean free path was not size limited. The sample was heated with eddy currents and the internal temperature was monitored using the susceptibility of the PrNi5. Our results show that the boundary conductance follows T2 between 2 - 15 mK. We also observed a ∼ 3.5 times increase in the conductance as the applied field was increased from 0 to 400 gauss, but no dependence on pressure or the presence of superfluid. While the field dependence cannot be explained, the temperature dependence is that expected for a magnetic spin glass.