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.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.

Journal of the Physical Society of JapanNov 10, 200816 citations

Homogeneous spin precession in rotating vortex-free He3 -B: Measurement of the superfluid density anisotropy

J. S. Korhonen, Yu. M. Bunkov, Vladimir V. Dmitriev +5 more

In transverse NMR at high rf excitation, it is possible to separate a $^{3}\mathit{B}$ sample into two magnetic domains. In one domain the spins are precessing coherently with a large tilting angle in relation to the polarizing magnetic field while in the other they are stationary and oriented parallel to the field. We have studied the two-domain system during vortex-free rotation and found that the boundary region between the precessing and static domains is sensitive to superfluid counterflow, flowing parallel to the boundary. The volume of the precessing domain decreases and the NMR absorption, associated with spin diffusion across the boundary, increases. The shift of the domain boundary is analyzed in terms of the competition between the kinetic energy of counterflow and the gradient in the Zeeman energy. From the shift we obtain the superfluid density anisotropy, induced by the magnetic field. A calculation in the weak-coupling approximation explains only half of the measured ansiotropy at low pressures. At high pressures the discrepancy is smaller.In transverse NMR at high rf excitation, it is possible to separate a $^{3}\mathit{B}$ sample into two magnetic domains. In one domain the spins are precessing coherently with a large tilting angle in relation to the polarizing magnetic field while in the other they are stationary and oriented parallel to the field. We have studied the two-domain system during vortex-free rotation and found that the boundary region between the precessing and static domains is sensitive to superfluid counterflow, flowing parallel to the boundary. The volume of the precessing domain decreases and the NMR absorption, associated with spin diffusion across the boundary, increases. The shift of the domain boundary is analyzed in terms of the competition between the kinetic energy of counterflow and the gradient in the Zeeman energy. From the shift we obtain the superfluid density anisotropy, induced by the magnetic field. A calculation in the weak-coupling approximation explains only half of the measured ansiotropy at low pressures. At high pressures the discrepancy is smaller.

Physical review. B, Condensed matterDec 1, 199216 citations

Momentum and spin transport properties of spin polarized Fermi systems

Wei Lijuan

We carried out experiments on a spin polarized 3He- 4He mixture with 3He concentration x 3 = 6.26 × 10−4, and on pure 3He liquid. Spin polarization affects the transport properties of these Fermi systems. The effect on momentum transport was studied by using a vibrating-wire viscometer to measure viscosity of the 3He-4He mixture over the temperature range 6.09 mK–100 mK in 7.96 T and 1.00 T magnetic fields. A large viscosity increase was observed upon application of the 7.96 T magnetic field for temperature T < TF(TF = 19.5 mK is the Fermi temperature). The observed viscosity is in very good agreement with theoretical calculations for a dilute Fermi gas by Jeon and Mullin [1988, 1989] and Mullin and Jeon [1992]. The polarization effect on spin transport was investigated by measuring the transverse diffusion coefficient D ⊥ in pure 3He liquid at saturated vapor pressure and at 15.85 bar over the temperature range 4.5 mK–159 mK in a 7.96 T magnetic field. We used a pulsed NMR spin echo technique in a field gradient of 16.0 G/cm to do the measurements and fits to the Leggett equations [1970] to obtain D⊥. For T < 20 mK, we found D⊥ is less than measured in earlier experiments at lower magnetic fields. D⊥ does not increase with decreasing temperature as 1/T2, but appears to approach a constant as T → 0 while it is expected that the longitudinal spin diffusion coefficient D∥ ∝ 1/ T2. This is called spin diffusion anisotropy and it was observed for the first time in our 3He liquid experiments. The anisotropy temperature we determined for 3He liquid was Ta = 16.4 ± 2.2 mK at saturated vapor pressure and in a 7.96 T magnetic field. The transverse spin diffusion in 3 He results agree qualitatively with theories proposed by Meyerovich and Musaeflan [1992, 1994]. They also agree qualitatively with theories proposed by Golosov and Ruckenstein [1995, 1998] by extrapolation of the dilute theory to a strongly interacting system.We carried out experiments on a spin polarized 3He- 4He mixture with 3He concentration x 3 = 6.26 × 10−4, and on pure 3He liquid. Spin polarization affects the transport properties of these Fermi systems. The effect on momentum transport was studied by using a vibrating-wire viscometer to measure viscosity of the 3He-4He mixture over the temperature range 6.09 mK–100 mK in 7.96 T and 1.00 T magnetic fields. A large viscosity increase was observed upon application of the 7.96 T magnetic field for temperature T < TF(TF = 19.5 mK is the Fermi temperature). The observed viscosity is in very good agreement with theoretical calculations for a dilute Fermi gas by Jeon and Mullin [1988, 1989] and Mullin and Jeon [1992]. The polarization effect on spin transport was investigated by measuring the transverse diffusion coefficient D ⊥ in pure 3He liquid at saturated vapor pressure and at 15.85 bar over the temperature range 4.5 mK–159 mK in a 7.96 T magnetic field. We used a pulsed NMR spin echo technique in a field gradient of 16.0 G/cm to do the measurements and fits to the Leggett equations [1970] to obtain D⊥. For T < 20 mK, we found D⊥ is less than measured in earlier experiments at lower magnetic fields. D⊥ does not increase with decreasing temperature as 1/T2, but appears to approach a constant as T → 0 while it is expected that the longitudinal spin diffusion coefficient D∥ ∝ 1/ T2. This is called spin diffusion anisotropy and it was observed for the first time in our 3He liquid experiments. The anisotropy temperature we determined for 3He liquid was Ta = 16.4 ± 2.2 mK at saturated vapor pressure and in a 7.96 T magnetic field. The transverse spin diffusion in 3 He results agree qualitatively with theories proposed by Meyerovich and Musaeflan [1992, 1994]. They also agree qualitatively with theories proposed by Golosov and Ruckenstein [1995, 1998] by extrapolation of the dilute theory to a strongly interacting system.

Jan 1, 20010 citations

In transverse NMR at high rf excitation, it is possible to separate a

^{3}\mathit{B}

sample into two magnetic domains. In one domain the spins are precessing coherently with a large tilting angle in relation to the polarizing magnetic field while in the other they are stationary and oriented parallel to the field. We have studied the two-domain system during vortex-free rotation and found that the boundary region between the precessing and static domains is sensitive to superfluid counterflow, flowing parallel to the boundary. The volume of the precessing domain decreases and the NMR absorption, associated with spin diffusion across the boundary, increases. The shift of the domain boundary is analyzed in terms of the competition between the kinetic energy of counterflow and the gradient in the Zeeman energy. From the shift we obtain the superfluid density anisotropy, induced by the magnetic field. A calculation in the weak-coupling approximation explains only half of the measured ansiotropy at low pressures. At high pressures the discrepancy is smaller.