  One of the key factors that determine the fates of quantum many-body systems
in the zero temperature limit is the competition between kinetic energy that
delocalizes particles in space and interaction that promotes localization.
While one dominates over the other in conventional metals and insulators,
exotic states can arise at quantum critical points where none of them clearly
wins. Here we present a novel metallic state that is realized at the
antiferromagnetic (AF) quantum critical point in space dimensions three and
below. At the critical point, interactions between particles are screened to
zero in the low energy limit at the same time the kinetic energy is suppressed
in certain spatial directions to the leading order in a perturbative expansion
that becomes asymptotically exact in three dimensions. The resulting
dispersionless and interactionless state exhibits distinct quasi-local strange
metallic behaviors due to the subtle dynamical balance between screening and
infrared singularity caused by the spontaneous reduction of effective
dimensionality.
