| Summary: | The spin-dynamics of Fermi-liquid helium-3 in pure form and in its
mixtures with helium-4 are considered in this thesis. A linearised
model of the spin dynamics is developed from Leggett's equation of
motion, including spin-diffusion, the Leggett-Rice spin-rotation
effect and cylindrical boundary conditions . The equations are
solved using a matrix formalism, allowing simulation of FIDs, NMR
spectra and spin-echoes. The boundary conditions are shown to
cause deviations of spin-echo amplitude and phase from the
predictions of Leggett and Rice, for realistic experiments. The
model is extended to include the demagnetising field (dipolar
field) due to the magnetisation of the sample itself. Simulations
show that, when the demagnetising field is strong, spectral
clustering is present and sharp peaks are observed in the NMR
spectrum.
Data from NMR experiments on 3He and 3He-4He mixtures in
an 11.3T magnetic field, performed in Nottingham in 1999/2000, are
analysed. The analysis of 6.2% 3He mixture is predominantly by
least-squares fitting of the model (excluding demagnetising field)
to spin-echo data, yielding the transverse spin-diffusion
coefficient and spin-rotation parameter as functions of
temperature down to 3.4mK. Parameters are seen to deviate from the
1/Ta^2 characteristic of Fermi-liquid transport parameters, with
a 1/(T^2+Ta^2) form, indicative of spin-transport anisotropy.
The anisotropy temperature scale Ta is found to be 6+-1 mK.
Analysis of pure 3He experiments is by qualitative comparison
of spectroscopic data with the model (including demagnetising
field): many observed features are reproduced by the simulation.
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