Shear Viscosity of Superfluid 3He up to 15 Tesla

We present the first measurements of the viscosity of superfluid 3He in magnetic fields up to 15 T , at temperatures down to 2 mK along the melting curve, using an assumption for the temperature dependence of the normal density. At fields higher than 4 T , the viscosity shows a minimum in the A1 phase, and reaches a local maximum at the A2 transition which becomes global at 14.6 T . The sharp decrease just below the A1 transition can be understood within the Ginzburg-Landau framework and is consistent with both theory and experiments in lower fields. At temperatures below the minimum, the viscosity in the A1 phase is dominated by a term with T-2 dependence. Additionally, we have calculated the temperature dependence of the viscosity tensor in the low temperature limit using the method of temperature asymptotes. copyright 1997 The American Physical Society