title: Switching of a coupled spin pair in a single-molecule junction.
abstract: Single-molecule spintronics investigates electron transport through magnetic molecules that have an internal spin degree of freedom. To understand and control these individual molecules it is important to read their spin state. For unpaired spins, the Kondo effect has been observed as a low-temperature anomaly at small voltages. Here, we show that a coupled spin pair in a single magnetic molecule can be detected and that a bias voltage can be used to switch between two states of the molecule. In particular, we use the mechanically controlled break-junction technique to measure electronic transport through a single-molecule junction containing two coupled spin centres that are confined on two Co(2+) ions. Spin-orbit configuration interaction methods are used to calculate the combined spin system, where the ground state is found to be a pseudo-singlet and the first excitations behave as a pseudo-triplet. Experimentally, these states can be assigned to the absence and occurrence of a Kondo-like zero-bias anomaly in the low-temperature conductance data, respectively. By applying finite bias, we can repeatedly switch between the pseudo-singlet state and the pseudo-triplet state.
authors.affiliation: Lehrstuhl für Angewandte Physik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 7, D-91058 Erlangen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Wagner
authors.forename: Ferdinand
authors.initials: F
authors.lastname: Kisslinger
authors.forename: Stefan
authors.initials: S
authors.lastname: Ballmann
authors.forename: Frank
authors.initials: F
authors.lastname: Schramm
authors.forename: Rajadurai
authors.initials: R
authors.lastname: Chandrasekar
authors.forename: Tilmann
authors.initials: T
authors.lastname: Bodenstein
authors.forename: Olaf
authors.initials: O
authors.lastname: Fuhr
authors.forename: Daniel
authors.initials: D
authors.lastname: Secker
authors.forename: Karin
authors.initials: K
authors.lastname: Fink
authors.forename: Mario
authors.initials: M
authors.lastname: Ruben
authors.forename: Heiko B
authors.initials: HB
authors.lastname: Weber