Longitudinal magnetic resonance (NMR) in the A1 phase of superfluid3He

Pertti Juhani Hakonen, M. Krusius, M.M. Salomaa +5 more

Marina Bastea, Haruo Kojima

Harry Kojima, Hidehiko Ishimoto

Under applied magnetic field, the originally single superfluid 3 He transition near 3 mK in zero field splits into two transitions between which a new A 1 phase emerges. The two second order transitions are marked by abrupt changes in viscosity, zero sound attenuation and nuclear magnetic resonance. To date, the maximum magnetic field for producing A 1 phase is 15 T. The A 1 phase has been identified with a spin-polarized (ferromagnetic) superfluid system which breaks the relative symmetry between spin, orbit and gauge spaces. A superfluid mass current in A 1 is simultaneously a spin current resulting in the propagation of spin-entropy wave. Experiments with spin-entropy wave provide measurements of anisotropic superfluid density and strong coupling parameters, spin diffusion coefficient and texture transformations. Owing to the spin-polarized nature, superflows may be generated by applied magnetic field gradients and measured from the induced magnetic fountain pressure. The mechanical spin density detector is developed to measure the spin relaxation in A 1 phase. The observed unexpected temperature dependence of the spin relaxation time gives evidence that the A 1 phase contains a small amount of the predicted minority spin condensate from dipolar interaction energy.

Akira Yamaguchi, Sora Kobayashi, Hidehiko Ishimoto +1 more

Andrei A. Zvyagin

The excitation of the A and A1 phases of superfluid 3He by a variable field parallel to a constant field is studied. It is shown that the longitudinal varying magnetic field does not cause a parametric instability in the system since the excitations in 3He are fermions. For small values of time, the magnetization of the system oscillates with the pumping frequency, as well as with a low resonance frequency whose value in the resonance is determined by the amplitude of the varying field. Introduction of the collision relaxation leads to a damping of the low-frequency oscillations. As the amplitude of the pumping field increases, the power absorbed by the system becomes limited.

V. P. Mineev, M.M. Salomaa, Olli V. Lounasmaa