Low Temperature Physics

Spin dynamics of He3-B with dissipation for the general spin-orbital configurations

G. A. Kharadzé, N. G. Suramlishvili

Published Aug 1, 1999• 1 citation

Abstract

The spatially homogeneous spin dynamics of the superfluid He3-B with dissipation is considered for the general spin-orbital configurations. It is demonstrated that the possibility of new coherent spin-precessing modes appears explicitly in the equations of motion describing the relaxation of the spin variables towards various attractors (resonance states) found previously as the stationary solutions and observed experimentally.

DOI: 10.1063/1.593789

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Low Temperature Physics

Spin dynamics of He3-B with dissipation for the general spin-orbital configurations

G. A. Kharadzé, N. G. Suramlishvili

Published Aug 1, 1999• 1 citation

Publisher

Abstract

DOI: 10.1063/1.593789

Related papers

Stable Spin Precession at One Half of Equilibrium Magnetization in Superfluid 3 He-B

Vladimir V. Dmitriev, Ivan V. Kosarev, M. Krusius +3 more

New modes of spin precession have been observed in superfluid ${}^{3}\mathrm{He}\ensuremath{-}B$ with a precessing magnetization ${M\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}pM}_{\mathrm{eq}}$ , where $p\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$ , $\frac{1}{2}$ , and $\ensuremath{\approx}0$. These dynamic order parameter states are the first examples of stable precession with a magnetization different from the equilibrium value ${M}_{\mathrm{eq}}$ . The $p\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\frac{1}{2}$ mode is the second example of a phase-coherent state of a spin superfluid. The new states can be excited close to ${T}_{c}$ in the range $1\ensuremath{-}T/{T}_{c}\ensuremath{\lesssim}0.02$ where dissipation is low and the energy barriers between the different local minima of the spin-orbit energy are small.New modes of spin precession have been observed in superfluid ${}^{3}\mathrm{He}\ensuremath{-}B$ with a precessing magnetization ${M\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}pM}_{\mathrm{eq}}$, where $p\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$, $\frac{1}{2}$, and $\ensuremath{\approx}0$. These dynamic order parameter states are the first examples of stable precession with a magnetization different from the equilibrium value ${M}_{\mathrm{eq}}$. The $p\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\frac{1}{2}$ mode is the second example of a phase-coherent state of a spin superfluid. The new states can be excited close to ${T}_{c}$ in the range $1\ensuremath{-}T/{T}_{c}\ensuremath{\lesssim}0.02$ where dissipation is low and the energy barriers between the different local minima of the spin-orbit energy are small.

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Pavel Krotkov, V. P. Mineev

Journal of Experimental and Theoretical PhysicsOct 1, 19980 citations

New modes of spin precession have been observed in superfluid ${}^{3}\mathrm{He}\ensuremath{-}B$ with a precessing magnetization

{M\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}pM}_{\mathrm{eq}}

, where

p\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1

\frac{1}{2}

, and $\ensuremath{\approx}0$. These dynamic order parameter states are the first examples of stable precession with a magnetization different from the equilibrium value

{M}_{\mathrm{eq}}

. The

p\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\frac{1}{2}

mode is the second example of a phase-coherent state of a spin superfluid. The new states can be excited close to

{T}_{c}

in the range $1\ensuremath{-}T/{T}_{c}\ensuremath{\lesssim}0.02$ where dissipation is low and the energy barriers between the different local minima of the spin-orbit energy are small.

On the Spin-Orbital Structure of the "Zero" Magnetization Spin-Precessing Modes of the Superfluid

^3He-B

The spin-orbital configurations of the coherently precessing spin modes characterized by a small value of the magnetization

(M\ll M_{0}=χH_{0})

is considered. Various regimes are analysed depending on the transverse rf-field strength

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.

\mathbf{L}

of the Cooper pairs is oriented transverse to the external magnetic field in a ``non-Leggett'' configuration with broken spin-orbit coupling. The resonance shift depends on the tipping angle $\ensuremath{\theta}$ of the magnetization as $\ensuremath{\omega}\ensuremath{-}{\ensuremath{\omega}}_{L}=({\ensuremath{\Omega}}_{B}^{2}/2{\ensuremath{\omega}}_{L})(\mathrm{cos}\ensuremath{\theta}\ensuremath{-}1/5).$ The phase diagram of the precessing modes with arbitrary orientation of

\mathbf{L}

is constructed.