Vertex corrections and the Korringa ratio in strongly correlated electron materials

TitleVertex corrections and the Korringa ratio in strongly correlated electron materials
Publication TypeJournal Article
Year of Publication2009
AuthorsYusuf, E., Powell Ben J., and McKenzie Ross H.
JournalJournal Of Physics-Condensed Matter
Volume21
Issue19
Pagination195601
Date Published05/2009
Abstract

We show that the Korringa ratio, associated with nuclear magnetic resonance in metals, is unity if vertex corrections to the dynamic spin susceptibility are negligible, the hyperfine coupling is momentum independent, and there exists an energy scale below which the density of states is constant. In the absence of vertex corrections we also find a Korringa behaviour for T-1, the nuclear spin relaxation rate, i.e., 1/T-1 proportional to T, and a temperature independent Knight shift. These results are independent of the form and magnitude of the self-energy (so far as is consistent with neglecting vertex corrections) and of the dimensionality of the system.

DOI10.1088/0953-8984/21/19/195601