Spin Polarized Superfluid ^3He A_1(<SPECIAL TOPICS>New Frontiers of Quantum Fluids and Solids)

概要

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Under applied magnetic field, the originally single superfluid ^3He transition near 3mK 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 15T. 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.
社団法人日本物理学会の論文
2008-11-15