title: Kondo Impurities in the Kitaev Spin Liquid: Numerical Renormalization Group Solution and Gauge-Flux-Driven Screening.
abstract: Kitaev's honeycomb-lattice compass model describes a spin liquid with emergent fractionalized excitations. Here, we study the physics of isolated magnetic impurities coupled to the Kitaev spin-liquid host. We reformulate this Kondo-type problem in terms of a many-state quantum impurity coupled to a multichannel bath of Majorana fermions and present the numerically exact solution using Wilson's numerical renormalization group technique. Quantum phase transitions occur as a function of Kondo coupling and locally applied field. At zero field, the impurity moment is partially screened only when it binds an emergent gauge flux, while otherwise it becomes free at low temperatures. We show how Majorana degrees of freedom determine the fixed-point properties, make contact with Kondo screening in pseudogap Fermi systems, and discuss effects away from the dilute limit.
authors.affiliation: Institut für Theoretische Physik, Technische Universität Dresden, 01062 Dresden, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Vojta
authors.affiliation: Institute for Theoretical Physics, Utrecht University, 3584 CE Utrecht, The Netherlands.
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Mitchell
authors.affiliation: Institut für Theoretische Physik, Technische Universität Dresden, 01062 Dresden, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Zschocke