2 research outputs found
Fractionalization of holographic Fermi surfaces
Zero temperature states of matter are holographically described by a
spacetime with an asymptotic electric flux. This flux can be sourced either by
explicit charged matter fields in the bulk, by an extremal black hole horizon,
or by a combination of the two. We refer to these as mesonic, fully
fractionalized and partially fractionalized phases of matter, respectively. By
coupling a charged fluid of fermions to an asymptotically AdS_4
Einstein-Maxwell-dilaton theory, we exhibit quantum phase transitions between
all three of these phases. The onset of fractionalization can be either a first
order or continuous phase transition. In the latter case, at the quantum
critical point the theory displays an emergent Lifshitz scaling symmetry in the
IR.Comment: 1+24 pages. 7 figure
Strange metals and the AdS/CFT correspondence
I begin with a review of quantum impurity models in condensed matter physics,
in which a localized spin degree of freedom is coupled to an interacting
conformal field theory in d = 2 spatial dimensions. Their properties are
similar to those of supersymmetric generalizations which can be solved by the
AdS/CFT correspondence; the low energy limit of the latter models is described
by a AdS2 geometry. Then I turn to Kondo lattice models, which can be described
by a mean- field theory obtained by a mapping to a quantum impurity coupled to
a self-consistent environment. Such a theory yields a 'fractionalized Fermi
liquid' phase of conduction electrons coupled to a critical spin liquid state,
and is an attractive mean-field theory of strange metals. The recent
holographic description of strange metals with a AdS2 x R2 geometry is argued
to be related to such mean-field solutions of Kondo lattice models.Comment: 19 pages, 4 figures; Plenary talk at Statphys24, Cairns, Australia,
July 2010; (v2) added refs; (v3) more ref