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https://hdl.handle.net/2142/25443
Description
Title
Topics in low temperature Fermi liquid theory
Author(s)
Hess, Daryl Wayne
Issue Date
1987
Doctoral Committee Chair(s)
Pines, David
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
low termperature Fermi liquid theory
quantum liquids
elementary excitation spectrum
Language
en
Abstract
Several topics in quantum liquids are discussed including the elementary excitation spectrum
of 3 He under pressure, spin polarized 3 He, and an early attempt to formulate a Fermi
liquid theory to describe the low temperature thermodynamic and transport properties of
the heavy electron system UPt3.
The elementary excitation spectrum of ordinary liquid 3 He is calculated at several pressures
using the polarization potential theory of Aldrich and Pines together with a simple
model to describe the effect of multipair excitations. The calculated elementary excitation
spectra, with no adjustable parameters, agree well with the recent experiment of Scherm
et al.
The effective interactions between quasi particles in fully spin polarized 3 He are obtained
from physical arguments and sum rules. The interactions between two down spin impurities
and that between an up and down spin are also deduced. The volume occupied by a down
spin impurity is found to be 17% to 7% less than that occupied by an up· spin. Nonlocal
scalar pseudopotentials of the Aldrich-Pines form are developed along with two extreme
models for the momentum dependent backflow potential. The transport properties are
calculated and found to be two to three orders of magnitude larger than those of the
unpolarized liquid at the same density. The elementary excitation spectrum is found to be
quite sensitive to the momentum dependence of the backflow potential.
The regime of small polarization is considered next. Using the phenomenological model
of Bedell and Sanchez-Castro together with an ansatz form for the spin flip interaction, a
large increase in the singlet scattering rate as a function of polarization is obtained. The
transport properties are calculated as a function of polarization and the viscosity obtained
is found to be in good agreement with the recent experiment of P. Kopietz et al.
Finally, an early attempt at describing the low temperature thermodynamic and transport
properties of the heavy electron system UPt3 by an extension of Landau Fermi liquid
theory is described. Although the Fermi surface geometry is treated naively, the transport
calculations underscore the importance of electron-electron scattering in these systems.
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