Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 74: Surface and Interface Magnetism II (O jointly with MA)
O 74.6: Vortrag
Donnerstag, 3. April 2014, 11:45–12:00, WIL C107
Protection of excited spin states by a superconducting energy gap — •Benjamin W. Heinrich1, Lukas Braun1, José I. Pascual1,2, and Katharina J. Franke1 — 1Institut für Experimentalphysik, Freie Universität Berlin, Germany — 2CIC nanoGUNE, San Sebastián, and Ikerbasque, Basque Foundation for Science, Bilbao, Spain.
The ability to tune the magnetism of individual atoms or molecules and to control their interaction with the environment is a key requirement for their use in potential spintronic applications. We employ scanning tunneling microscopy and spectroscopy at 1.2 K to characterize the spin state of individual metal-organic complexes, namely Fe(III)-Octaethylporphyrin-Chloride, adsorbed on a superconducting Pb(111) surface. The organic ligand provides an anisotropic environment for the spin of the Fe ion (S=5/2), which leads to a zero field splitting of the spin eigenstates. The superconducting gap in the density of states of the substrate now stabilizes excited spin states of the Fe as it hinders the exchange of energy and angular momentum between the substrate’s quasi-particles and the molecular spin. This allows for lifetimes of ≈ 10 ns of the excited spin state [1]. Furthermore we examine the influence of our probe, the STM tip, on the zero field splitting of the Fe ion. Even at a distance of several Angstrom between tip and molecule a sizable change of the magnetic anisotropy is detected.
[1] B. W. Heinrich et al. Nature Physics, doi:10.1038/nphys2794.