45th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 59, Number 8
Monday–Friday, June 2–6, 2014;
Madison, Wisconsin
Session T2: Invited Session: Transport in Degenerate Gases
8:00 AM–10:00 AM,
Friday, June 6, 2014
Room: Ballroom CD
Chair: Joseph Thywissen, University of Toronto
Abstract ID: BAPS.2014.DAMOP.T2.1
Abstract: T2.00001 : Transverse Spin Diffusion
8:00 AM–8:30 AM
Preview Abstract
Abstract
Author:
William Mullin
(Physics Department, University of Massachusetts Amherst)
Transverse spin diffusion is a relatively new transport coefficient
and a review of its history and physical basis will be presented.
In NMR spin diffusion is often measured by spin echo techniques, which
involve spin currents perpendicular to the direction of the magnetization,
in contrast with the usual longitudinal case where the current is
parallel to the magnetization. The first indication that this involved
new physics was the Leggett-Rice effect (1970) in which spin waves,
new spin-echo behavior, and an altered spin diffusion coefficient
were predicted in liquid $^{3}$He. This effect gave the possibility
of the first measurement of $F_{1}^{a}$, the parameter of the Landau
Fermi-liquid theory mean-field responsible for the effect. In 1982
Lhuillier and Laloe found a transport equation very similar to the
Leggett equation, but valid for highly-polarized dilute Boltzmann
Bose and Fermi gases, and describing the ``identical spin rotation
effect'' (ISRE), the analog of a Landau mean field. Coincidentally
Bashkin and Meyerovich had also given equivalent descriptions of transport
in polarized Boltzmann gases. That a mean-field effect could exists
in dilute Boltzmann gases was theoretically surprising, but was confirmed
experimentally. At low polarization the basic transverse diffusion
constant $D_{\perp}$ coincides with the longitudinal value $D_{\parallel}$;
however Meyerovich first pointed out that they could differ in highly
polarized degenerate gases. Indeed detailed calculations (Jeon and
Mullin) showed that, while $D_{\parallel}$
is proportional to $T^{-2}$, $D_{\perp}$ approaches
a constant (depending on polarization) at low $T$. Considerable
controversy existed until experimental verification was achieved in
2004. The importance of ISRE again arose in 2008 as the basis of ``anomalous
spin-state segregation'' in Duke and JILA experiments. More recently
application of the ideas of transverse spin diffusion to strongly
interacting Fermi gases has resulted in the observation of the diffusion
constants at the quantum limit where $D\sim\hbar/m.$
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2014.DAMOP.T2.1