title: Magnetic anisotropy variations and nonequilibrium tunneling in a cobalt nanoparticle.
abstract: We present detailed measurements of the discrete electron-tunneling level spectrum within nanometer-scale cobalt particles as a function of magnetic field and gate voltage, in this way probing individual quantum many-body eigenstates inside ferromagnetic samples. Variations among the observed levels indicate that different quantum states within one particle are subject to different magnetic anisotropy energies. Gate-voltage studies demonstrate that the low-energy tunneling spectrum is affected dramatically by the presence of nonequilibrium spin excitations.
authors.affiliation: Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Deshmukh
authors.forename: S
authors.initials: S
authors.lastname: Kleff
authors.forename: S
authors.initials: S
authors.lastname: Guéron
authors.forename: E
authors.initials: E
authors.lastname: Bonet
authors.forename: A N
authors.initials: AN
authors.lastname: Pasupathy
authors.forename: J
authors.initials: J
authors.lastname: von Delft
authors.forename: D C
authors.initials: DC
authors.lastname: Ralph