Two-dimensional spin networks with coordination and covalent bonds
J.P. Bucher
Institut de Physique et de Chimie des Matériaux de Strasbourg, UMR 7504, Université de Strasbourg,
67034 Strasbourg
jean-pierre.bucher@ipcms.unistra.fr
In the bottom up approach of today’s nanoscience, the supramolecular assembly of metal
atoms and molecules on surfaces is leading to functional compounds, relevant to many
applications in optoelectronics, magnetism, and catalysis. It has been found that in some cases
high magnetic spin states and strong magnetic anisotropy appear as a result of electron
transfer between ligands, surface and metal atom [1]. The ultimate development in this area is
based on the generation of surface covalent bonding between molecules leading to extended
organometallic pi-conjugated networks containing magnetic atoms [2].
On the other hand, the fundamental understanding of electron/spin transport in reduced
dimensions, down to the extreme limit of individual molecules remains one of the main
challenges in the emerging field of spintronics. Here, low temperature scanning tunneling
spectroscopy (STS) and spin polarized scanning tunnelling spectroscopy (SP-STS) [3,4] are
used to get a deeper insight into the spin properties of Fe and Co based networks and single
molecules adsorbed on a well characterized metal surfaces. The configuration of the STM,
with its tip opposite the surface, makes it a privileged instrument to probe magnetic and
transport properties on a local basis. In particular, we will focus on the local dI/dV analysis of
the metal centers at different steps of a Fe-(TCNB)x network formation. The TCNB molecule
is particularly important in this context since it plays a role as intermediate radical in the
formation of phthalocyanines. Comparison with the metallo-phthalocyanines by means of the
SP-STS experiments, allows describing a coherent picture that will be presented at the
conference. Furthermore by applying a novel atomic manipulation technique, the STM is
used to provide unprecedented resolution on the adsorption geometry of the molecule. This
information together with local dI/dV spectroscopy, allows mapping of the electronic
properties and, together with the DFT calculation, provides useful links between chemical
bonding and magnetic properties.
[1] P. Gambardella et al. Nature Materials, 8,189 (2009).
[2] M. Abel, S. Clair, O. Ourdjini, M. Mossoyan, L. Porte, J. Am. Chem. Soc., 133, 1203 (2011).
[3] C. Iacovita, M.V. Rastei, B.W. Heinrich, T. Brumme, J. Kortus, L. Limot, and J.P. Bucher, Phys. Rev. Lett.
101, 116602 (2008).
[4] B.W. Heinrich, C. Iacovita, Th. Brumme, D.J. Choi, L. Limot, M.V. Rastei, J. Kortus, W.A. Hofer, and J.P.
Bucher, J. Phys. Chem. Lett. 1,1517 (2010).