Spin Polarized Superfluid³He A₁

Abstract

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.KEYWORDS: spin-polarized system, superfluid 3 He, magnetic fountain effect, spin pump, second sound, high magnetic field

Application of Boltzmann Equation on Spin Diffusion of Ferromagnetic Superfluid 3He: Near Critical Temperature

“…This is in sharp contrast to the situation in other stable phases of superfluid 3 He; namely, A-phase and B-phase [5,8]. Since the discovery of the new phases of 3 He, a good deal of theoretical work has been done on spin collective excitation [9][10][11]. Transport in a superfluid Fermi liquid can be associated with spin supercurrents (superfluid component) [2,12,13].…”

“…It should be noted that the direction of the applied magnetic field affects the production of A 1 -phase; additionally, the magnetic moment of the superfluid component is aligned in the same direction as that of the applied magnetic field [6]. Recently, a notable detailed study has been carried out on spin polarized superfluid 3 He-A 1 and its properties [3,7]. In the superfluid phases of 3 He, both mass and spin supercurrents can be induced [5,8].…”

“…Recently, a notable detailed study has been carried out on spin polarized superfluid 3 He-A 1 and its properties [3,7]. In the superfluid phases of 3 He, both mass and spin supercurrents can be induced [5,8]. In the A 1 -phase, these two supercurrents are not independent of each other; rather, they coexist.…”

“…Nonhydrodynamic behavior of the spin transport can be influenced by reactive Fermi-liquid forces. The spin transport parameters, particularly the spin diffusion coefficient, are anisotropic in all stable phases of superfluid Fermi liquid 3 He, even in superfluid 3 He-B which has an isotropic gap. Spin diffusion is in general a fourth-rank tensor which can be characterized by three independent components [2].…”

“…The first measurement of the transverse component of the spin diffusion tensor of B-phase at low temperatures is available [13]. In the following, steps taken to measure spin diffusion of A 1 -phase are pointed out: the attenuation of spin-entropy wave in A 1 -phase of superfluid 3 He was measured and investigated [3,6,22,32,33]. Theoretically, the attenuation of spin-entropy depends on spin diffusion coefficient and other dissipative coefficients.…”