Transverse Dynamics in SpinPolarized and Binary Fermi Liquids.
Abstract
I discuss transverse dynamics in spinpolarized Fermi liquids such as itinerant magnets, ^3 Heuparrow, and ^3 Heuparrow^4 He mixtures. I derive exact microscopic equations of transverse dynamics in spinpolarized and binary Fermi liquids at zero temperature using the Green's functions method. The transverse dynamics is described by an inherently nonlocal integral equation in a 4D momentum space. This equation is equivalent to a set of two coupled equations for "partial transverse densities" which correspond generically to contributions from tilted spinups and spindowns. In contrast to previous phenomenological attempts to describe polarized Fermi liquids, these two equations reduce to a single Landaulike kinetic equation only for low polarization or density. The molecular field has the form of a 4component complex nonlocal operator. This interaction operator is related to the exact irreducible vertex via an integral equation, and cannot be given, as it is usually assumed, as any limit of the full vertex. The dephasing of inhomogeneous precession of dressed spinup and spindown pseudoparticles leads to a peculiar zerotemperature attenuation. The case of a dilute Fermi gas is analyzed by means of perturbation theory. I demonstrate how the exact theory reduces to the conventional theory of highly polarized dilute Fermi gases. For an ideal polarized Fermi gas and in the first order in density, the theory assumes the standard form. In the next order, the main equations still have a fairly conventional form, though they already contain the peculiar zerotemperature attenuation which is missing in the standard theory. In the third order, the standard theory fails completely, and even the form of equations of transverse dynamics becomes unconventional. The parameters of transverse spin dynamics and the spectrum of spin waves, including zerotemperature attenuation are calculated explicitly. As a byproduct, the polarization dependences of the thermodynamic parameters are determined. An application of the results to ^3Heuparrow ^4He mixtures includes effects of nonlocality in the direct interaction channel and the retardation in the phononmediated part of particle interaction. I also developed a field/polarization expansion for spin dynamics in arbitrary dense Fermi liquids.
 Publication:

Ph.D. Thesis
 Pub Date:
 1993
 Bibcode:
 1993PhDT.......158M
 Keywords:

 Physics: Condensed Matter