title: Impact of reduced symmetry on magnetic anisotropy of a single iron phthalocyanine molecule on a Cu substrate.
abstract: We study the magnetic anisotropy of a single iron phthalocyanine (FePc) molecule on a Cu(110) (2 × 1)-O by using inelastic electron tunneling spectroscopy (IETS) with low-temperature scanning tunneling microscopy. Two inelastic excitations derived from the splitting of the molecular triplet spin state appear as two pairs of steps symmetrically with respect to zero sample voltage. We measured IETS spectra with external magnetic fields perpendicular and parallel to the molecular plane, and we analyzed the spectral evolution with the effective spin Hamiltonian approach. We determined all parameters related with magnetic anisotropy at a single-molecule level, both the easy- and hard-magnetization directions, zero-field splitting constant, D = - 4.0 meV and E = 1.1 meV, the Lande g-tensor gxx, gyy, gzz=(1.82, 2.02, 2.34), and the constant of spin-orbit coupling λ = - 19.1 meV. We stress that the symmetry breaking caused by the adsorption of FePc on the oxidized Cu(110) significantly impacts the magnetic anisotropy.
authors.affiliation: Department of Advanced Materials Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Tsukahara
authors.affiliation: Department of Advanced Materials Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Kawai
authors.affiliation: Department of Advanced Materials Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Takagi