Berlin 2012 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 36: Spins in Organic Materials (jointly with MA)
DS 36.6: Vortrag
Donnerstag, 29. März 2012, 18:00–18:15, H 1012
Electronic structure and magnetic properties of metallocene multiple-decker sandwich nanowires — Cristian Morari1, Florian Beiuseanu2, and •Liviu Chioncel3 — 1National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, RO-400293 Cluj Napoca, Romania — 2Department of Physics, University of Oradea, RO-410087 Oradea, Romania — 3Augsburg Center for Innovative Technologies, University of Augsburg, D-86135 Augsburg, Germany
We present a study of the electronic and magnetic properties of the multiple-decker sandwich nanowires (CP-M) composed of cyclopentadienyl (CP) rings and 3d transition metal atoms (M=Ti to Ni) using Density Functional Theory first-principles techniques. We demonstrate that structural relaxation is an important effect in determining the magnetic ground-state of the system. Notably, the computed magnetic moment is zero in CP-Mn, while in CP-V a significant turn-up in magnetic moment is evidenced. CP-Fe/Cr show a half-metallic ferromagnetic ground state with a gap within minority/majority spin channel. In order to study the effect of electronic correlations upon the half-metallic ground states in CP-Cr, we introduce a simplified three-bands Hubbard model which is solved within the Variational Cluster Approach. We discuss the results as a function of size of the reference cluster and the strength of average Coulomb U and J exchange parameters. For range of studied parameters U=2-4eV and J=0.6-1.2eV the half-metallic character is not maintained in the presence of local Coulomb interactions.