title: Local defect in metallic quantum critical systems.
abstract: We present a theory of a single point, line, or plane defect coupling to the square of the order parameter in a metallic system near a quantum critical point at or above its upper critical dimension. At criticality, a spin droplet is nucleated around the defect with its core size determined by the strength of the defect potential. Outside the core a universal slowly decaying tail of the droplet is found, leading to many dissipative channels coupling to the droplet and to a complete suppression of quantum tunneling. We propose an NMR experiment to measure the impurity-induced changes in the local spin susceptibility.
authors.affiliation: Center for Materials Theory, Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Millis
authors.forename: D K
authors.initials: DK
authors.lastname: Morr
authors.forename: J
authors.initials: J
authors.lastname: Schmalian