Berlin 2008 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 2: Towards Molecular Spintronics

DS 2.3: Hauptvortrag

Montag, 25. Februar 2008, 12:45–13:15, H 2013

Substrate-induced magnetic ordering and switching of iron porphyrin molecules — •H. Wende¹, M. Bernien², J. Luo², C. Weis¹, N. Ponpandian², J. Kurde², J. Miguel², M. Piantek², X. Xu², Ph. Eckhold², W. Kuch², K. Baberschke², P. Srivastava¹, P.M. Panchmatia³, B. Sanyal³, P.M. Oppeneer³, and O. Eriksson³ — ¹Universität Duisburg-Essen, Fachbereich Physik — ²Freie Universität Berlin, Fachbereich Physik — ³Department of Physics, Uppsala University, Sweden

Paramagnetic porphyrin molecules in contact with a metallic substrate are promising as building blocks in molecular nano-electronics. For this purpose the manipulation of the spin of the central 3d atom in this biologically significant molecule is essential. Here, we study the structural orientation and the magnetic coupling of in-situ sublimated Fe porphyrin molecules on ferromagnetic Ni and Co films which are epitaxially grown on Cu(100). These studies utilize NEXAFS at the C and N K-edges, and XMCD at the Fe, Co and Ni L_2,3-edges, which provide element-specific magnetic properties. In a combined experimental-computational study we demonstrate that due to an indirect, super-exchange interaction between Fe atoms in the molecules and atoms in the substrate (Co or Ni) the paramagnetic molecules can be made to order ferromagnetically. The Fe magnetic moment can be rotated along directions in-plane as well as out-of-plane by a magnetization reversal of the substrate, thereby opening up an avenue for spin-dependent molecular electronics. Supported by BMBF (05KS4KEB5) and DFG (SFB 658, Heisenberg-Programm).