title: Local quantum criticality of an iron-pnictide tetrahedron.
abstract: Motivated by the close correlation between transition temperature (T(c)) and the tetrahedral bond angle of the As-Fe-As layer observed in the iron-based superconductors, we study the interplay between spin and orbital physics of an isolated iron-arsenide tetrahedron embedded in a metallic environment. Whereas the spin-Kondo effect is suppressed to low temperatures by Hund's coupling, the orbital degrees of freedom are expected to quantum mechanically quench at high temperatures, giving rise to an overscreened, non-Fermi liquid ground state. Translated into a dense environment, this critical state may play an important role in the superconductivity of these materials.
authors.affiliation: Center for Materials Theory, Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: T Tzen
authors.initials: TT
authors.lastname: Ong
authors.forename: Piers
authors.initials: P
authors.lastname: Coleman