Anisotropic Spin Diffusion in Trapped Boltzmann Gases

Mullin, William J.; Ragan, Robert

doi:10.1007/s10909-005-2291-2

Cited by 3 publications

(4 citation statements)

References 16 publications

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“…Since the distribution functions in equilibrium are functions of | Σ| according to (16), i.e. functions of b 2 ⊥ and b 3 , and since the latter ones are even in momentum direction, the distributions are even in momentum direction as well.…”

Section: Spin and Density Wavesmentioning

confidence: 99%

“…If the range of interaction is shorter than the DeBroglie wavelength, such excitations are also predicted [8][9][10][11][12][13] and observed 14,15 in dilute spin-polarized gases. The transverse spin-wave dynamics has been the subject of a series of theoretical investigations 12,16 . In ultracold gases, spin waves have been observed, even spatially resolved 17,18 , and were described by longitudinal spin waves 19 .…”

Section: Introductionmentioning

confidence: 99%

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Kinetic theory of spin-polarized systems in electric and magnetic fields with spin-orbit coupling. II. RPA response functions and collective modes

Morawetz

2015

Phys. Rev. B

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The spin and density response functions in the random phase approximation (RPA) are derived by linearizing the kinetic equation including a magnetic field, the spin-orbit coupling, and mean fields with respect to an external electric field. Different polarization functions appear describing various precession motions showing Rabi satellites due to an effective Zeeman field. The latter turns out to consist of the mean-field magnetization, the magnetic field, and the spin-orbit vector. The collective modes for charged and neutral systems are derived and a threefold splitting of the spin waves dependent on the polarization and spin-orbit coupling is shown. The dielectric function including spin-orbit coupling, polarization and magnetic fields is presented analytically for long wave lengths and in the static limit. The dynamical screening length as well as the long-wavelength dielectric function shows an instability in charge modes, which are interpreted as spin segregation and domain formation. The spin response describes a crossover from damped oscillatory behavior to exponentially damped behavior dependent on the polarization and collision frequency. The magnetic field causes ellipsoidal trajectories of the spin response to an external electric field and the spin-orbit coupling causes a rotation of the spin axes. The spin-dephasing times are extracted and discussed in dependence on the polarization, magnetic field, spin-orbit coupling and single-particle relaxation times.

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Section: Spin and Density Wavesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Kinetic theory of spin-polarized systems in electric and magnetic fields with spin-orbit coupling. II. RPA response functions and collective modes

Morawetz

2015

Phys. Rev. B

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“…To make the physics behind these spin oscillations more accessible, [10] performed a small amplitude moment expansion of the spin distribution, [7] considered the excitations in the hydrodynamic limit where spin perturbations are never far from equilibrium values, and [11] compared the two methods. These linear approximations give analytical results that allow for a better conceptual understanding of the phenomenon, and they accurately predict the small amplitude behavior of the spin excitations.…”

Section: Spin Wave Theorymentioning

confidence: 99%

Optical excitation of nonlinear spin waves

McGuirk¹,

Zajiczek

2010

New J. Phys.

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We demonstrate a technique for exciting spin waves in an ultracold gas of 87 Rb atoms based on tunable AC Stark potentials. This technique allows us to excite normal modes of spin waves with arbitrary amplitudes in the trapped gas, including dipole, quadrupole, octupole, and hexadecapole modes. These modes exhibit strong nonlinearities, which manifest as amplitude dependence of the excitation frequencies and departure from sinusoidal behavior. Our results are in good agreement with a full treatment of a quantum Boltzmann transport equation.

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“…We have previously reported results on the dipolar modes. [15] In our previous work, Ref. 10, we derived an analog of the Landau-Silin equation for a 2×2 density operator n p (here acting in the pseudo-spin space), with effective mean-field single particle energy matrixǫ p .…”

Section: I Introductionmentioning

confidence: 99%

Spin diffusion in trapped gases: Anisotropy in dipole and quadrupole modes

Mullin

Ragan

2006

Phys. Rev. A

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Recent experiments in a mixture of two hyperfine states of trapped Bose gases show behavior analogous to a spin-1/2 system, including transverse spin waves and other familiar Leggett-Ricetype effects. We have derived the kinetic equations applicable to these systems, including the spin dependence of interparticle interactions in the collision integral, and have solved for spin-wave frequencies and longitudinal and transverse diffusion constants in the Boltzmann limit. We find that, while the transverse and longitudinal collision times for trapped Fermi gases are identical, the Bose gas shows unusual diffusion anisotropy in both dipole and quadrupole modes. Moreover, the lack of spin isotropy in the interactions leads to the non-conservation of transverse spin, which in turn has novel effects on the hydrodynamic modes.

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Anisotropic Spin Diffusion in Trapped Boltzmann Gases

Cited by 3 publications

References 16 publications

Kinetic theory of spin-polarized systems in electric and magnetic fields with spin-orbit coupling. II. RPA response functions and collective modes

Kinetic theory of spin-polarized systems in electric and magnetic fields with spin-orbit coupling. II. RPA response functions and collective modes

Optical excitation of nonlinear spin waves

Spin diffusion in trapped gases: Anisotropy in dipole and quadrupole modes

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