Showing papers by "M. Knupfer published in 2011"
TL;DR: In this paper, the electronic properties of two metal phthalocyanines, CuPc and MnPc, have been investigated by a combined experimental and theoretical approach, and it was shown that the highest occupied molecular orbital has significant metal 3D character.
47 citations
TL;DR: In this paper, the authors investigated the effect of low oxygen pressure on the performance of the Ti-O bonding in a soft x-ray spectroscopy setup and identified two types of charge carriers, one located at the Fermi energy and related to the filling of the SrTiO-SrTiO conduction band.
Abstract: We investigated LaAlO${}_{3}$-SrTiO${}_{3}$ heterointerfaces grown either in oxygen-rich or -poor atmosphere by soft x-ray spectroscopy. Resonant photoemission across the Ti L${}_{2,3}$ absorption edge of the valence band and Ti 2$p$ core-level spectroscopy directly monitor the impact of oxygen treatment upon the electronic structure. Two types of Ti${}^{3+}$ related charge carriers are identified. One is located at the Fermi energy and related to the filling of the SrTiO${}_{3}$ conduction band. It appears for low oxygen pressure only. The other one is centered at ${E}_{B}\ensuremath{\approx}1$ eV and independent of the oxygen pressure during growth. It is probably due to defects. The magnitude of both excitations is comparable. It is shown that low oxygen pressure is detrimental for the Ti-O bonding. Our results shed light on the nature of the charge carriers in the vicinity of the LaAlO${}_{3}$-SrTiO${}_{3}$ interface.
32 citations
TL;DR: In this paper, the dynamic response of pristine and potassium-doped picene, the first example of a new family of organic molecular superconductors, was investigated by combining first-principles calculations and state-of-the-art experimental tools.
Abstract: We investigate the dynamic response of pristine and potassium-doped picene, the first example of a new family of organic molecular superconductors, by combining first-principles calculations and state-of-the-art experimental tools. We find that charge-carrier plasmons in K${}_{3}$ picene have a negative or almost negligible dispersion, which deviates from the traditional picture of metals based on the homogeneous electron gas. We show how this finding is the result of the competition between metallicity and electronic localization on the molecular units. Conduction electrons alone give rise to the negative dispersion, which is reduced by molecular polarization and crystal local-field effects. This analysis allows us to obtain a general picture of the plasmon dispersion in metallic molecular crystals.
25 citations
TL;DR: In this article, Haberer and Gruneis proposed a method to solve the problem of particle filtering in the context of physics and applied it in the field of physics at the Max-Planck-Institut fur Polymerforschung (MIPF) in Germany.
Abstract: D. Haberer*,1, L. Petaccia2, Y. Wang3, H. Quian3, M. Farjam4, S. A. Jafari4,5, H. Sachdev6,7, A. V. Federov8, D. Usachov8, D. V. Vyalikh8,9, X. Liu10, O. Vilkov8,9, V. K. Adamchuk8, S. Irle3, M. Knupfer1, B. Buchner1, and A. Gruneis1,10 1 IFW Dresden, P.O. Box 270116, 01171 Dresden, Germany 2 Elettra Synchrotron Light Laboratory, Sincrotrone Trieste SCpA, S.S. 14 Km 163.5, 34149 Trieste, Italy 3 Department of Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan 4 Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran, Iran 5 Department of Physics, Sharif University of Technology, Tehran 11155-9161, Iran 6 Anorganische Chemie 8.11, Universitat des Saarlandes, 66041 Saarbrucken, Germany 7 Max-Planck-Institut fur Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany 8 St. Petersburg State University, St. Petersburg 198504, Russia 9 Institut fur Festkorperphysik, TU Dresden, Mommsenstrasse 13, 01069 Dresden, Germany 10 Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Wien, Austria
18 citations
Posted Content•
TL;DR: In this paper, the authors investigated the impact of oxygen treatment upon the electronic structure of a 2p core level spectroscopy core-level spectroglobe and showed that low oxygen pressure is detrimental for the Ti-O bonding.
Abstract: We investigated \LAO\ - \STO\ heterointerfaces grown either in oxygen rich or poor atmosphere by soft x-ray spectroscopy Resonant photoemission across the Ti L$_{2,3}$ absorption edge of the valence band and Ti 2p core level spectroscopy directly monitor the impact of oxygen treatment upon the electronic structure Two types of Ti$^{3+}$ related charge carriers are identified One is located at the Fermi energy and related to the filling of the \STO\ conduction band It appears for low oxygen pressure only The other one is centered at E$_{B}$ $\approx$ 1 eV and independent of the oxygen pressure during growth It is probably due to defects The magnitude of both excitations is comparable It is shown that low oxygen pressure is detrimental for the Ti - O bonding Our results shed light on the nature of the charge carriers in the vicinity of the \LAO\ - \STO\ interface
4 citations