Annual Report 2014

## Electronic correlations

_{3}Ir

_{3}O

_{8}with a chiral hyper-kagome lattice, the inverse-perovskites M

_{3}TrO (Tr = tetrel element: Si, Ge, Sn, Pb), and also iron-based superconductors such as Fe

_{2}Se

_{2}. From the spectroscopic side, we employ inelastic neutron scattering, spin-polarized scanning tunneling microscopy, and magnetization measurements. Finally, we analyze the resulting electronic correlations theoretically, in particular, their non-Fermi-liquid behavior, the origin of quantum interference and provide insights to a Mott-insulating state by a many-electron wavefunction.

** Semi-metallic ground state of hyper-kagome iridate Na _{3}Ir_{3}O_{8} produced by a competion of molecular orbital split and spin-orbit coupling **

T. Takayama, A. Yaresko, A. Matsumoto, J. Nuss, and H. Takagi

** Tilted inverse-perovskites, new class of three-dimensional Dirac electron systems **

J. Nuss, A. W. Rost, C. Mühle, K. Hayama, V. Abdolazimi, and H. Takagi

** Effect of Te doping on the structure and superconductivity of K _{0.8}Fe_{2}Se_{2-z}Te_{z} single crystals **

M. T. Li, W.P. Liu, and C. T. Lin

** Electronic ordering in perovskites and the effects on the symmetry of crystal structures **

M. Etter, M. Isobe, H. Sakurai, R. E. Dinnebier, and H. Takagi

** Competing exchange interactions on the verge of a metal-insulator transition in the two-dimensional spiral magnet Sr _{3}Fe_{2}O_{7} **

J.-H. Kim, A. Jain, G. Khaliullin, D. C. Peets, C. Ulrich, A. C. Walters, D. S. Inosov, A. Maljuk, and B. Keimer

** Atomic-scale imaging of magnetic order in strongly correlated electron systems **

R. Aluru, M. Enayat, Z. Sun, U. R. Singh, S. Schmaus, A. Yaresko, Y. Liu, C. T. Lin, and P. Wahl

** Polar instability through strong magneto-elastic coupling in bulk EuTiO _{3}: Small cause, large impact **

P. G. Reuvekamp, K. Caslin, R. K. Kremer, J. Köhler, and A. Bussmann-Holder

** Non-Fermi liquid behavior in two-dimensional metals at the onset of incommensurate density wave order **

T. Holder and W. Metzner

** Interference effects in two-dimensional chiral metal with vacancies **

P. M. Ostrovsky

** Insight into the many-electron wavefunction of Mott-insulating antiferromagnets **

L. R. Schwarz and A. Alavi

## Heterostructures

_{3}–SrTiO

_{3}interfaces, the ferromagnetic metallic state in atomically thin SrRuO

_{3}, spin and charge ordered states in nickelates and manganites as precisely controled via epitaxial strain and oxygen deficiency. Coming to organic electronics, one of the highlights reports on the successful fabrication of fast organic complementary circuits on flexible plastic substrates.

** Evidence for superconducting vortices in the insulating regime of the LaAlO _{3}–SrTiO_{3} interface electron system **

E. Fillis-Tsirakis, C. Richter, J. Mannhart, and H. Boschker

** Ferromagnetism and conductivity in atomically thin SrRuO _{3} **

H. Boschker, T. Harada, C. R. Hughes, A. V. Boris, and J. Mannhart

** ****Effects of SrRuO _{3} on properties of functional oxide heterostructures **

I. Vrejoiu

** Tunable charge and spin order in PrNiO _{3} thin films and superlattices **

M. Hepting, M. Minola, A. Frano, G. Cristiani, G. Logvenov, M. Wu, M. Bluschke, H.-U. Habermeier, E. Benckiser, M. Le Tacon, and B. Keimer

** Precise defect control in complex oxides thin epitaxial films **

K. Kawashima, F. Baiutti, G. Christiani, H.-U. Habermeier, and G. Logvenov

** Fast organic complementary circuits on flexible plastic substrates **

U. Kraft, M. Sejfić, R. Rödel, M. Aghamohammadi, U. Zschieschang, and H. Klauk

## Low dimensional quantum systems

** Atomic exchange bias control of individual quantum magnets **

S. Yan, D.-J. Choi, J. A. J. Burgess, S. Rolf-Pissarczyk, and S. Loth

** Tracking temperature dependent relaxation times with a wide-band quantum spectrometer **

M. Ternes , E. Schäfer-Nolte, L. Schlipf, F. Reinhard, J. Wrachtrup, and K. Kern

** A plasmon emitting transistor based on a single molecule **

Ch. Große, A. Kabakchiev, Th. Lutz, R. Froidevaux, M. Etzkorn, U. Schlickum, K. Kuhnke, and K. Kern

** Magnetic flux periodic conductance modulations in mesoscopic two-paths quantum Hall devices **

L. Schulz, J. Weis, and K. v. Klitzing

** ****Negative compressibility of the bubble and stripe phases in the quantum Hall regime**** **

B. Frieß, K. v. Klitzing, and J. Smet (currently not available!)

** Covalent modification of graphene by hyperthermal collisions **

G. Dubey, R. Urcuyo, S. Abb, G. Rinke, M. Burghard, S. Rauschenbach, and K. Kern

## Materials for energy conversion

_{4}) and how it is stored (e.g. at abrupt junctions) is investigated in detail. Since materials with a multitude of different kinds of charge carriers are quite common in materials for electrochemical energy conversion, the transport behavior of a model system (with protons, oxide ion vacancies and electronic holes being the charge carriers) is described in a quantitative way.

** Crystalline carbon nitride nanosheets for improved visible-light hydrogen evolution **

K. Schwinghammer, M. B. Mesch, V. Duppel, Ch. Ziegler, J. Senker, B. V. Lotsch

** A hydrazone-based covalent organic framework for photocatalytic hydrogen production **

L. Stegbauer, K. Schwinghammer, and B. V. Lotsch

** Engineering the surface properties of titanium dioxide for photocatalysis **

C. Dette, C. S. Kley, P. Punke, G. Rinke, J. Čechal, P. Jacobson, S. Rauschenbach, S. Stepanow, S. J. Jung, and K. Kern

** Phase evolution in single-crystalline LiFePO _{4} followed by in-situ scanning X-ray microscopy of a micrometer-sized battery **

N. Ohmer, B. Fenk, D. Samuelis, C.-C. Chen, M. Weigand, E. Goering, G. Schütz, and J. Maier

** Thermodynamics of lithium storage at abrupt junctions: Modeling and experimental evidence **

L. J. Fu, C.-C. Chen, D. Samuelis, and J. Maier

** Solution of the three-carrier problem: A natural explanation for surprising observations **

D. Poetzsch, R. Merkle, and J. Maier

Annual Report 2013

## Low-dimensional quantum systems

** Signatures of a Wigner crystal in the chemical-potential evolution of a two dimensional electron system **

D. Zhang, X. Huang, W. Dietsche, K. v. Klitzing, and J.H. Smet

** Probing the microscopic structure of the stripe phase at filling factor 5/2**

B. Friess, K. von Klitzing, and J.H. Smet

** Current distribution and Hall potential landscape at the breakdown of the Quantum Hall Effect in small samples **

K. Panos, J. Weis, R.R. Gerhardts, and K. v. Klitzing

** Individual molecules as gates for plasmonic light emission **

T. Lutz, Ch. Große, Ch. Dette, A. Kabakchiev, R. Gutzler, K. Kuhnke, U. Schlickum, and K. Kern

** Ultrafast dynamics of quantum confined carriers in a single CdSe nanowire **

T. Schumacher and M. Lippitz

** Vector magnetic field characterization of individual atoms **

S. Yan, J. Burgess, D.-J. Choi, S. Rolf-Pissarczyk, and S. Loth

## Functional interfaces and heterostructures

**Monolithically integrated circuits from functional oxides**

C. Richter, C. Woltmann, G. Pfanzelt, B. Foerg, M. Rommel^{}, T. Reindl^{}, U. Waizmann^{}, J. Weis^{}, H. Boschker, and J. Mannhart

**Two-dimensional electron gas in SrTiO _{3} probed by quantum oscillations**

H. Nakamura

**Digital synthesis of multicomponent oxides – We can design novel materials**

F. Baiutti, F. Wrobel, Ch. Dietl, G. Christiani, and G. Logvenov

**Stabilization of high Curie temperature in manganite/ruthenate superlattices with ultrathin layers**

I. Vrejoiu

**Megahertz operation of flexible organic transistors**

U. Zschieschang, U. Kraft, R. Rödel, M. Sejfić, R. Hofmockel, M. Aghamohammadi, S. Bisoyi, and H. Klauk

## Unconventional superconductivity and electronic correlations

_{2}Cu

_{3}O

_{6.6}using inelastic X-ray scattering as well as in the Cu-intercalated superconductor PdTe2. Next, we analyze the role of orbital degrees of freedom if a competition between triplet superconductivity and ferromagnetism takes place followed by a general theoretical approach employing functional Renormalization Group combined with Mean-Field Theory to study the competition between singlet superconductivity and antiferromagnetism in the ground state of the 2D Hubbard model. Further electronic correlations are demonstrated by measuring magnon lifetimes in the 2D and 3D antiferromagnets Rb

_{2}MnF

_{4}and MnF

_{2}, respectively, by a new high-resolution neutron technique as well as in the spin-1/2 linear chain ferromagnet CuAs

_{2}O

_{4}. This section will be closed by the discovery of the Kondo effect in the weak-coupling regime in a purely organic molecule and by a new extension of the Density Functional Theory applied to the dilute magnetic semiconductor GaMnAs.

**Giant phonon anomalies and central peak due to charge density wave formation in YBa _{2}Cu_{3}O_{6.6}**

M. Le Tacon, S.M. Souliou, T. Loew, and B. Keimer

**Cu-intercalated superconductor of PdTe _{2} with CdI_{2}-type structure**

G.H. Ryu, M.T. Li, D.P. Chen, and C.T. Lin

**Role of orbital states at the Interface of a triplet superconductor and a ferromagnet**

D. Manske

**Competing order in interacting electron systems made simple**

J. Wang, A. Eberlein, and W. Metzner

**Lifetimes of antiferromagnetic magnons in two and three dimensions**

Ph. Leininger, T. Keller, and B. Keimer

**Characterization of the spin-1/2 linear-chain ferromagnet Trippkeite (CuAs _{2}O_{4})**

K. Caslin, R.K. Kremer, and A. Schulz

**Temperature and magnetic field dependence of a Kondo system in the weak coupling regime**

Y. Zhang, S. Kahle, T. Herden, U. Schlickum, M. Ternes, P. Wahl, and K. Kern

**Defect states in semiconductors: Mn acceptor in GaAs**

J. Jackson and G. Bester

## Materials for energy conversion and storage

**Bio-inspired nanocatalysts for the oxygen reduction reaction**

D. Grumelli, B. Wurster, S. Stepanow, and K. Kern

**Tetragonal Li _{10}GeP_{2}S_{12} and Li_{7}GePS_{8} – structure and Li ion dynamics of LGPS Li electrolytes**

A. Kuhn, V. Duppel, J. Köhler, and B.V. Lotsch

**Concentration polarization in salt containing liquid and liquid-solid composite electrolytes**

C. Pfaffenhuber, J. Popovic, and J. Maier

**How to get a conversion reaction reversible? Lithium and sodium storage in MoS _{2} nanodots**

C. Zhu, X. Mu, P.A. van Aken, Y. Yu, and J. Maier

**Mobility of oxygen vacancies in perovskites: Insights from experiments and ab-initio calculations**

R. Merkle, E.A. Kotomin, and J. Maier

**Thermoelectronic conversion of solar energy and heat into electric power**

C. Stephanos, G. Hassink, I. Rastegar, and J. Mannhart

## Unusual solids

**Kawazulite – A natural topological insulator**

P. Gehring, H.M. Benia, R. Dinnebier, Y. Weng, C.R. Ast, M. Burghard, and K. Kern

**Artificial solids by design: Assembly and electron microscopy study of nanosheet-derived heterostructures**

C. Ziegler, S. Werner, M. Wörsching, V. Duppel, and B.V. Lotsch

**X-ray powder diffraction meets the thermosalient effect – The jumping crystals**

T. Runčevski and R.E. Dinnebier

Annual Report 2012

## Structure and properties of crystalline compounds

_{2}

_{}semiconductors, we gained insight into why the conventional increase in the band gap with decreasing temperature turns into an anomalous non-monotonic behavior when the divalent cation is replaced by monovalent d-electron copper or silver, e.g. in AgGaSe

_{2}. Even less expected was the recent discovery of superconductivity controlled by copper intercalation between the Se layers in the prototypical topological insulator Bi

_{2}Se

_{3}. The growth of single crystals of Cu

_{x}Bi

_{2}Se

_{3}with various Cu contents has been optimized. Interest to structures with intercalated metal atoms makes it very topical to develop methods for accurate reconstruction of their electron density distribution from X-ray diffraction data. A general method using maximum entropy has been developed for localization of missing intercalated metal atoms in apatites. Titanium oxides continue to surprise with their unusual electron transport and structural properties which can be tuned by introducing dislocations or by applying a magnetic field.

**Temperature dependence of band gaps in semiconductors: electron-phonon interaction**

M. Cardona, R. Lauck, and R.K. Kremer

**Crystal growth and anomalous transport properties of Cu _{x}Bi_{2}Se**

_{3}M.T. Li and C.T. Lin

**Reconstruction of electron density by the Maximum Entropy Method from X-ray powder diffraction data based on incomplete crystal structure models: a case study of apatites with different intercalated metal atoms**

O.V. Magdysyuk, R.E. Dinnebier, and M. Jansen

**Altering electrical properties by "one-dimensional doping": Case study of TiO**_{2}K.K. Adepalli, M. Kelsch, R. Merkle, and J. Maier

**Magnetic field enhanced structural instability in EuTiO**_{3}J. Köhler, R. Dinnebier, and A. Bussmann-Holder

## Electronic correlations and superconductivity

_{2}and the iron-selenide superconductor Rb

_{2}Fe

_{4}Se

_{5}.

**Gutzwiller Theory of Band Magnetism in LaOFeAs**

L. Boeri and O.K. Andersen

**Dimerization and Entanglement in Spin-Orbital Chains**

W.-L. You, A. Herzog, J. Sirker, A.M. Oleś, and P. Horsch

**Functional renormalization group study of superconductivity in the two-dimensional Hubbard model**

A. Eberlein and W. Metzner

** CuBr _{2} - A New Multiferroic Material with High Critical Temperature**

R.K. Kremer, M.G. Banks, and A. Simon

**Nanoscale layering of antiferromagnetic and superconducting phases in Rb _{2}Fe_{4}Se**

_{5}A. Charnukha, D. Pröpper, A.N. Yaresko, B. Keimer, and A.V. Boris

## Quantum Hall effect

**Current-induced asymmetries in narrow quantum Hall systems**

R.R. Gerhardts, K. Panos, J. Weis, and K. v. Klitzing

**Quantized ν=5/2 state in a Two-Subband Quantum Hall System**

J. Nuebler, B. Friess, K. v. Klitzing, and J.H. Smet

**Edge Contribution to the Hall Potential Profiles in Graphene under Quantum Hall Conditions**

K. Panos, J. Weis, B. Krauss, and K. v. Klitzing

**Transconductance fluctuations probe interaction physics in graphene**

D.-S. Lee, V. Skakalova, R.T. Weitz, K. v. Klitzing, and J.H. Smet

## Two-dimensional systems and interfaces

_{3}and LaAlO

_{3}. The electronic compressibility of this electronic system has been studied with Kelvin probe microscopy. The long-range transfer of electron-phonon coupling through the interfaces between oxide materials has been observed and demonstrates that epitaxial oxide superlattices offer novel opportunities to generate vibrational modes that do not exist in the bulk. The complexity of artificial heterostructures requires the development of new methods of rational calculation of their electronic structure. A new methodology has been developed to derived atomic effective pseudopotentials for semiconductor superlattices.

**Magnetic and superconducting phases at the LaAlO _{3}-SrTiO_{3} interface**

N. Pavlenko and J. Mannhart

**Probing the electronic compressibility of LaAlO _{3}-SrTiO_{3} interfaces by Kelvin probe microscopy**

C. Richter and J. Mannhart

**Long-range transfer of electron-phonon coupling in oxide superlattices**

N. Driza, S. Blanco-Canosa, M. Bakr, S. Soltan, M. Khalid, L. Mustafa, K. Kawashima, G. Christiani, H.-U. Habermeier, G. Khaliullin, C. Ulrich, M. Le Tacon, and B. Keimer

**Atomic effective pseudopotentials for semiconductor nanostructures calculations**

Cardenas and G. Bester

## Physics and chemistry on the nanoscale

_{2}N surfaces. Furthermore, different fabrication methods of nanomaterials are discussed, such as stereoselective self-assembly and van der Waals epitaxial growth procedures.

**The Quantum Magnetism of Individual Manganese-12-Acetate Molecular Magnets Anchored at Surfaces**

S. Kahle, Z. Deng, N. Malinowski, C. Tonnoir, A. Forment-Aliaga, N. Thontasen, G. Rinke, S. Rauschenbach, M. Ternes, and K. Kern

**Atomically assembled antiferromagnets**

D.-J. Choi, S. Yan, and S. Loth

**Stereoselectivity and electrostatics in charge-transfer Mn- and Cs-TCNQ _{4} networks on Ag(100)**

N. Abdurakhmanova, T.-C. Tseng, S. Stepanow, and K. Kern

**High-mobility 3D topological insulator nanoplatelets on hBN sheets**

P. Gehring, B. Gao, M. Burghard, and K. Kern

**A Close Look at Proteins**

S. Rauschenbach, Z. Deng, N. Thontasen, N. Malinowski, G. Rinke, and K. Kern

## Materials with technological prospects

**Stimuli-responsive two-dimensional photonic crystals based on polyelectrolyte hydrogel for optically encoded sensing**

C. Li and B.V. Lotsch

**Porosity and stoichiometry as efficient means to optimize Li storage in anatase**

D. Samuelis, J.-Y. Shin, and J. Maier

**Prediction and verification of Li ^{+} charge transfer at LiF/TiO_{2} interfaces**

C.L. Li, D. Samuelis, K. Tang, and J. Maier

**Triazine-based Carbon Nitrides for Visible-Light-Driven Hydrogen Evolution**

K. Schwinghammer, B. Tuffy, M.B. Mesch, E. Wirnhier, C. Martineau, F. Taulelle, W. Schnick, J. Senker, and B.V. Lotsch

**Alignment of plasmonic nanostructures to self-assembled quantum dots with sub-10 nm accuracy**

K. Lindfors, M. Pfeiffer, B. Fenk, and M. Lippitz

**Air-stable, high-performance organic n-channel transistors**

U. Zschieschang, R. Rödel, M. Sejfic, U. Kraft, R. Hofmockel, and H. Klauk

Annual Report 2011

## Unconventional properties of superconductors

*T*

_{c}in Fe-based superconductors can be demonstrated. These measurements were only possible, because high-quality crystals had been grown. The resonant mode is a strong feedback effect of superconductivity on the magnetic spectrum. It is intimately related with the response at higher energies in Resonant Inelastic X-ray Scattering (RIXS) measurements, allowing a quantitative analysis of the strength of the magnetic pairing glue in the normal state. Analyzing a new class of non-centrosymmetric superconductors in which both singlet- and triplet-pairing simultaneously occur, one can find topologically-protected surface states that may be observed by tunneling spectroscopy. Further it is demonstrated that this technique can also be employed to determine the gap structure of the two-dimensional electron liquid formed at the interface of LaAIO

_{3}and SrTiO

_{3}. These results may be contrasted with the behavior of conventional superconductors such as doped picene. Finally, the role of the important Coulomb pseudopotential can be clarified by a modern Dynamical Mean Field Theory (DMFT) approach.

**Magnetic resonant mode in superconducting Rb _{x}Fe_{2-y}Se_{2}**

G. Friemel, J.T. Park, Yuan Li, J.-H. Kim, B. Keimer, and D. Inosov

**Floating-zone growth of K _{x}Fe_{2-y}Se_{2} single crystals**

Z.C. Li, W.P. Liu, Y. Liu, G. Friemel, D.S. Inosov, R.E. Dinnebier, and C.T. Lin

**Intense paramagnon excitations in a large family of high-temperature superconductors**

M. Le Tacon, J. Chaloupka, M.W. Haverkort, V. Hinkov, S. Blanco-Canosa, M. Bakr, G.L. Sun, Y.T. Song, C.T. Lin, G. Khaliullin, and B. Keimer

**Topologically protected surface states in non-centrosymmetric superconductors**

A.P. Schnyder, P.M.R. Brydon, S. Ryu, and C. Timm

**Tunnel spectroscopy of superconducting oxide interfaces**

C. Richter, H. Boschker, W. Dietsche, M. Hagel, and J. Mannhart

**Superconductivity in doped picene**

A. Subedi and L. Boeri

**Accuracy of Migdal-Eliashberg theory and Coulomb pseudopotential**

J. Bauer, J.E. Han, and O. Gunnarsson

## Low-dimensional carbon structures

** Label-free nucleic acid biosensors using carbon nanotubes**

T. Kurkina, A. Vlandas, A. Ahmad, K. Kern, and K. Balasubramanian

** Unipolar circuits based on individual-carbon-nanotube transistors**

H. Ryu, D. Kälblein, and H. Klauk

** Thermal fluctuations of crystalline membranes and ripple formation in graphene**

N. Hasselmann

** Excitonic Fano resonance in free-standing graphene**

D.-H. Chae, T. Utikal, S. Weisenburger, D. Ullrich, P. Herlinger, J. Smet, and M. Lippitz

** Quantum Hall effect in twisted bilayer graphene**

D.S. Lee, C. Riedl, T. Beringer, K. von Klitzing, U. Starke, and J.H. Smet

** Ambipolar doping in quasi-free epitaxial graphene on SiC(0001) controlled by Ge intercalation**

K.V. Emtsev, C. Coletti, S. Forti, and U. Starke

## Tailoring the properties of complex materials

** Josephson currents in the bilayer exciton condensate**

X. Huang, W. Dietsche, M. Hauser, and K. v. Klitzing

** Tunable one-dimensional photonic crystals based on metal-organic framework, silica and titania nanoparticles as sensing platforms**

I. Pavlichenko, A. Ranft, A.T. Exner, G. Scarpa, P. Lugli, F. Hinterholzinger, J.M. Feckl, T. Bein, and B.V. Lotsch

** Field-effect devices utilizing the two-dimensional electron liquid generated at LaAlO _{3}-SrTiO_{3} interfaces**C. Richter and J. Mannhart

** The fractional quantum Hall effect in wide quantum wells**

J. Nübler, B. Friess, K. v. Klitzing, and J.H. Smet

** A universal representation of the states of chemical matter including metastable configurations in phase diagrams**

M. Jansen, I.V. Pentin, and J.C. Schön

## Materials with technological prospects

** LiFePO _{4}: From single crystals to nanostructures**

C. Zhu, K. Weichert, L. Gu, and J. Maier

** Novel semi-solid electrolytes for Li-based batteries**

C. Pfaffenhuber, K. Weichert, A. Wohlfarth, K.-D. Kreuer, and J. Maier

** Searching for fast oxygen exchange kinetics: (Bi,Sr)(Fe,Co)O _{3-δ} perovskites**

A. Wedig, R. Merkle, B. Stuhlhofer, H.-U. Habermeier, E. Heifets, and J. Maier

** Modeling enzyme function at surfaces**

S. Stepanow, N. Lin, A. Dmitriev, J. Honolka, and K. Kern

** Flexible low-voltage organic transistors based on a novel, high-mobility organic semiconductor**

U. Zschieschang, U. Kraft, R. Rödel, M. Sejfic, and H. Klauk

** Optical Nano-Antennas**

R. Vogelgesang, M. Eßlinger, W. Khunsin, and K. Kern

## Structure and properties of crystalline compounds

_{1+x}CuO

_{2}Wigner crystals, or those involving large stable molecules, such as fullerenes. New methods of structural refinement are applied to characterize compounds with structural instabilities, which can be tuned by chemical substitution or electron doping. To reach a microscopic physical understanding of the diverse phenomena in crystalline compounds, first-principles calculations become indispensable, as they possess predictive power in describing electronic structures, vibrational properties of complex clusters, or explain the lattice distortions in compounds with heavy elements, in which relativistic effects start playing a major role.

** Disorder in rare earth metal halide carbide nitrides**

A. Simon, C. Schaloske, and Hj. Mattausch

** Mesostructured imidazolate frameworks**

S.C. Junggeburth, K. Schwinghammer, K.S. Virdi, C. Scheu, and B.V. Lotsch

** Prediction of new structure candidates for quasi one-dimensional Wigner crystals Na _{1+x}CuO_{2} (0 ≤ x ≤ 1) by enumeration**

J. Nuss, N.Z. Ali, U. Wedig, and M. Jansen

** Structural and electronic ordering phenomena in fullerides**

K.Yu. Amsharov and M. Jansen

** Symmetry mode based parametric Rietveld refinement of the structural phase transition of CuInSe _{2} **

M. Müller and R.E. Dinnebier

** Tuning the structural instability of SrTiO _{3} by Eu doping: the phase diagram of Sr_{1-x}Eu_{x}TiO_{3}**

A. Bussmann-Holder, J. Köhler, and R.K. Kremer

** Density functional analysis of the electronic structure of Cs _{9}InO_{4}: Evidence for the presence of a Cs^{-} anion**

J. Köhler, A. Simon, and C. Hoch

** Vibrational properties of colloidal semiconductor nanoclusters**

P. Han and G. Bester

** Relativistic effects on homonuclear triel clusters**

U. Wedig, J. Nuss, V. Saltykov, P. Dasari, F. Wang, and M. Jansen

## Electronic correlations

*ab initio*schemes and many-body methods; the results may be tested by various experimental techniques. Several highlights in this section are devoted to unconventional properties of low-dimensional materials with strong electronic correlations: First, the success of novel

*ab initio*cluster calculations is investigated which include the full Coulomb vertex for NiO. Next, the interesting Spin-Peierls transition in TiPO

_{4}both with magnetic measurements as well as with Density-Functional Theory (DFT) calculations is discussed. The measured anisotropic optical response of NaCu

_{2}O

_{2}shows fair agreement with the results of the LSDA+U method. This section will be closed by an experimental realization of the two-impurity Kondo problem by using Scanning Tunneling Microscopy (STM) and by theoretical investigations of a nematic quantum critical point.

** Multiplet ligand-field theory using Wannier orbitals**

M.W. Haverkort and O.K. Andersen

** Spin-Peierls transition in TiPO _{4}**

J.M. Law, C. Hoch, and R.K. Kremer

** Anisotropic optical response of the mixed-valent Mott-Hubbard insulator NaCu _{2}O_{2} **

A. Yaresko, Y. Matiks, A.V. Boris, B. Keimer, and O.K. Andersen

** A tunable two-impurity Kondo system in an atomic point contact**

J. Bork, Y. Zhang, P. Wahl and K. Kern

** Singular order parameter interaction at nematic quantum critical point**

W. Metzner and S.C. Thier