title: Tunable Kondo effect in a single donor atom.
abstract: The Kondo effect has been observed in a single gate-tunable atom. The measurement device consists of a single As dopant incorporated in a silicon nanostructure. The atomic orbitals of the dopant are tunable by the gate electric field. When they are tuned such that the ground state of the atomic system becomes a (nearly) degenerate superposition of two of the silicon valleys, an exotic and hitherto unobserved valley Kondo effect appears. Together with the "regular" spin Kondo, the tunable valley Kondo effect allows for reversible electrical control over the symmetry of the Kondo ground state from an SU(2) to an SU(4) configuration.
authors.affiliation: Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands. g.p.lansbergen@tudelft.nl
authors.forename: G P
authors.initials: GP
authors.lastname: Lansbergen
authors.forename: G C
authors.initials: GC
authors.lastname: Tettamanzi
authors.forename: J
authors.initials: J
authors.lastname: Verduijn
authors.forename: N
authors.initials: N
authors.lastname: Collaert
authors.forename: S
authors.initials: S
authors.lastname: Biesemans
authors.forename: M
authors.initials: M
authors.lastname: Blaauboer
authors.forename: S
authors.initials: S
authors.lastname: Rogge