Magnetic phenomena, ferro and antiferro Kondo, and transport in transition metal break junction nanocontacts

Transport in transition metal break junctions is of particular interest in connection with magnetism, which may be present either in the leads, and/or in bridging magnetic impurities, or else which may emerge spontaneously at the nanocontact, as expected in pristine Pt or Pd.[1] The standard Landauer ballistic conductance across the locally magnetic atomic contact is modified by Kondo phenomena that are predicted using ab initio electronic structure as a starting point, and the numerical renormalization group as a tool. The case of a magnetic impurity in a nonmagnetic contact[2] is shown to illustrate the competition between antiferro and ferro Kondo screening[3] and its effects on conductance. *) Work in collaboration with A. Smogunov, A. Dal Corso, L. De Leo, P. Gentile, M. Fabrizio, P. Lucignano, and R. Mazzarello. [1] A. Delin, et al., Phys. Rev. Lett. 92, 057201 (2004); A. Smogunov et al., Phys. Rev. B78, 014423 (2008). [2] R. Mazzarello, P. Lucignano, A. Smogunov, M. Fabrizio, and E. Tosatti, in preparation [3] P. Gentile, L. De Leo, M. Fabrizio, and E. Tosatti, in preparation