title: Ballistic Anisotropic Magnetoresistance of Single-Atom Contacts.
abstract: Anisotropic magnetoresistance, that is, the sensitivity of the electrical resistance of magnetic materials on the magnetization direction, is expected to be strongly enhanced in ballistic transport through nanoscale junctions. However, unambiguous experimental evidence of this effect is difficult to achieve. We utilize single-atom junctions to measure this ballistic anisotropic magnetoresistance (AMR). Single Co and Ir atoms are deposited on domains and domain walls of ferromagnetic Fe layers on W(110) to control their magnetization directions. They are contacted with nonmagnetic tips in a low-temperature scanning tunneling microscope to measure the junction conductances. Large changes of the magnetoresistance occur from the tunneling to the ballistic regime due to the competition of localized and delocalized d-orbitals, which are differently affected by spin-orbit coupling. This work shows that engineering the AMR at the single atom level is feasible.
authors.forename: J
authors.initials: J
authors.lastname: Schöneberg
authors.forename: F
authors.initials: F
authors.lastname: Otte
authors.affiliation: Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Néel
authors.forename: A
authors.initials: A
authors.lastname: Weismann
authors.affiliation: Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA , D-52425 Jülich, Germany.
authors.forename: Y
authors.initials: Y
authors.lastname: Mokrousov
authors.affiliation: Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Kröger
authors.forename: R
authors.initials: R
authors.lastname: Berndt
authors.forename: S
authors.initials: S
authors.lastname: Heinze
keywords: Ballistic anisotropic magnetoresistance; density functional theory; scanning tunneling microscopy; single atoms