  Since the mid-eighties there has been an accumulation of metallic materials
whose thermodynamic and transport properties differ significantly from those
predicted by Fermi liquid theory. Examples of these so-called non-Fermi liquids
include the strange metal phase of high transition temperature cuprates, and
heavy fermion systems near a quantum phase transition. We report on a class of
non-Fermi liquids discovered using gauge/gravity duality. The low energy
behavior of these non-Fermi liquids is shown to be governed by a nontrivial
infrared (IR) fixed point which exhibits nonanalytic scaling behavior only in
the temporal direction. Within this class we find examples whose
single-particle spectral function and transport behavior resemble those of
strange metals. In particular, the contribution from the Fermi surface to the
conductivity is inversely proportional to the temperature. In our treatment
these properties can be understood as being controlled by the scaling dimension
of the fermion operator in the emergent IR fixed point.
