title: Giant magnetoresistance through a single molecule.
abstract: Magnetoresistance is a change in the resistance of a material system caused by an applied magnetic field. Giant magnetoresistance occurs in structures containing ferromagnetic contacts separated by a metallic non-magnetic spacer, and is now the basis of read heads for hard drives and for new forms of random access memory. Using an insulator (for example, a molecular thin film) rather than a metal as the spacer gives rise to tunnelling magnetoresistance, which typically produces a larger change in resistance for a given magnetic field strength, but also yields higher resistances, which are a disadvantage for real device operation. Here, we demonstrate giant magnetoresistance across a single, non-magnetic hydrogen phthalocyanine molecule contacted by the ferromagnetic tip of a scanning tunnelling microscope. We measure the magnetoresistance to be 60% and the conductance to be 0.26G(0), where G(0) is the quantum of conductance. Theoretical analysis identifies spin-dependent hybridization of molecular and electrode orbitals as the cause of the large magnetoresistance.
authors.affiliation: Physikalisches Institut, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schmaus
authors.forename: Alexei
authors.initials: A
authors.lastname: Bagrets
authors.forename: Yasmine
authors.initials: Y
authors.lastname: Nahas
authors.forename: Toyo K
authors.initials: TK
authors.lastname: Yamada
authors.forename: Annika
authors.initials: A
authors.lastname: Bork
authors.forename: Martin
authors.initials: M
authors.lastname: Bowen
authors.forename: Eric
authors.initials: E
authors.lastname: Beaurepaire
authors.forename: Ferdinand
authors.initials: F
authors.lastname: Evers
authors.forename: Wulf
authors.initials: W
authors.lastname: Wulfhekel
mesh_terms: D003035:Cobalt / Q000737:chemistry; D003460:Crystallization / Q000379:methods; D004553:Electric Conductivity; D017097:Electric Impedance; D004566:Electrodes; D004581:Electronics / Q000379:methods; D004867:Equipment Design; D005240:Feasibility Studies; D005290:Ferric Compounds / Q000737:chemistry; D007211:Indoles / Q000737:chemistry*; D054833:Isoindoles; D008280:Magnetics / Q000295:instrumentation; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods; D016252:Microscopy, Scanning Tunneling; D036103:Nanotechnology / Q000379:methods*; D012815:Signal Processing, Computer-Assisted
chemical_list: D005290:Ferric Compounds; D007211:Indoles; D054833:Isoindoles; D058185:Magnetite Nanoparticles; C001215:ferrite; D003035:Cobalt; C013647:phthalocyanine