Contributions of the Max Planck Institute for Chemical Physics of Solids to the Yearbook of the Max Planck Society

2018

  • Evidence for Weyl fermions by the local nuclear magnetic resonance techniques

    2018 Baenitz, Michael
    Tantalum has one of the largest quadrupole moments among all elements which makes it a rather useful local probe for excitations of Weyl fermions in the new Weyl semimetal TaP. We found three NQR lines in a good agreement with theoretical calculations including spin orbit coupling. The temperature dependence of the spin lattice relaxation rate is attributed to the magnetic excitations at the Weyl nodes and a good agreement with predictions from theory could be found. The microscopic magnetic resonance techniques therefore provide new insides into the class of Weyl semimetals.

2017

  • The quantum sound of metals

    2017 Hassinger, Elena
    Every musical instrument has its own sound with a frequency spectrum that is determined by the shape of the instrument. In analogy to that, every metal has its characteristic frequency spectrum reflecting the properties of its electrons. Our investigation of the quantum sound of electrons in the metal PdRhO2 shows that electrons move quickly in the crystallographic planes whereas they hardly move perpendicular to the planes. The quantum music sounds slightly differently than expected and will help understand the particular hydrodynamic transport properties of electrons in these metals.

2016

  • Covalence and ionicity in compounds of MgAgAs-type: from concepts to structure prediction

    2016 Wagner, Frank R.; Bende, David; Grin, Yuri
    Analysis of chemical bonding in compounds of the MgAgAs type of structure by bonding indicators in position space resulted in a generalization of the 8­–N rule for bonds of variable polarity. Position-space indicators enable quantification of ionicity and covalence, which was successfully used to explain the different site preference in main-group and transition-metal compounds of the MgAgAs type. On this basis, it was possible to propose promising candidates for new compounds with the MgAgAs structure type, which was subsequently verified for the majority of compounds by laboratory synthesis.

2015

  • Topological Weyl semimetals

    2015 Yan, Binghai; Felser, Claudia
    In recent years, theoretical physicists discovered that the topology of a material can lead to interesting new quantum properties. This simple concept can be applied to the electronic structure of semiconducting materials in which relativistic effects are important. In 2015, several materials like NbP, NbAs, TaP, TaAs, und MoTe2 have been suggested by theoreticians as promissing, so-called Weyl semimetals, and have been physically characterized just a bit later. The special feature is that Weyl fermions, which occur in these materials as quasiparticles, exist in two chiralities.

2014

  • Hunting for the electrical properties of topological insulators

    2014 Höfer, Katharina; Becker, Christoph; Rata, Diana; Swanson, Jesse; Thalmeier, Peter; Tjeng, Liu Hao
    Topological insulators form a novel state of matter that open up new opportunities to create unique quantum particles. Many exciting experiments have been proposed by theory, but still await their experimental verification, not to mention their implementation into applications. The main obstacle is the extrinsic conductivity associated with the unavoidable presence of defects in their bulk, as well as impurities on their surfaces. For Bi2Te3 films it is possible to obtain the desired quality by carrying out the preparation and characterization entirely under ultra-high vacuum conditions.

2013

  • There's life in the old dog yet: discovery of a supercool magnet

    2013 Brando, Manuel; Steppke, Alexander; Küchler, Robert; Lausberg, Stefan; Lengyel, Edit; Steinke, Lucia; Borth, Robert; Lühmann, Thomas; Krellner, Cornelius; Pedrero, Luis; Pfau, Heike; Tencé, Sophie; Rosner, Helge; Nicklas, Michael; Steglich, Frank; Geibel, Christoph

    A ferromagnetic transition at an extremely low temperature of only 0.15 K (−273°C) has been discovered in the compound YbNi4P2. The properties of this phase transition contradict current theoretical predictions and evidence the existence of a ferromagnetic quantum critical point (QCP). The existence of such a QCP has been a matter of discussion as long as 40 years ago, but had been dismissed in the past 15. The search for and the investigation of QCPs is not only a central subject of modern fundamental research, but is also relevant in the development of new technical applications.

  • From palladium to noble metal-free hydrogenation catalysts – intermetallic compounds in catalysis

    2013 Armbrüster, Marc; Kovnir, Kyrill; Friedrich, Matthias; Grin, Yuri

    A knowledge-based concept has proven as efficient strategy for the development of innovative catalysts. Understanding of the crystal structure and the atomic interactions within intermetallic compounds allows for selection of suitable intermetallic compounds as effective hydrogenation catalysts. In contrast to the widely applied trial-and-error approach, the knowledge-based approach is an advantageous alternative, demonstrating the application potential of intermetallic compounds in heterogeneous catalysis.

2012

  • Novel quantum states in metals

    2012 Kirchner, Stefan; Wirth, Steffen; Pfau, Heike; Friedemann, Sven; Stockert, Oliver; Geibel, Christoph; Si, Qimao; Steglich, Frank
    Quantum criticality is currently pursued across many areas of correlated matter. A particular focus is on quantum criticality in itinerant electron systems. It has been shown that the traditional theory of metals breaks down in the vicinity of a novel class of quantum critical points in metals. A better understanding of the physics of these novel quantum states yields new insights into the occurence of magnetism and superconductivity.
  • Topological insulators from a chemical point of view

    2012 Felser, Claudia; Chadov, Stanislav; Müchler, Lukas; Yan, Binghai; Kübler, Jürgen; Zhang, Shou-Cheng1

    Topological insulators (TIs) are a new quantum state of matter, which have attracted interest of condensed matter science. The materials are small band gap insulators with robust gapless surface states. Remarkable is that topological insulators can be predicted by ab initio theory and even understood from a chemist’s perspective. Herein, a simple recipe based on bonds, bands, symmetry, and nuclear charge will be given to motivate a systematic search for new topologically nontrivial materials.

2011

  • Sr3[Co(CN)3] and Ba3[Co(CN)3]: "Simple" compounds with extensive consequences on the chemistry of highly reduced metalates

    2011 Höhn, Peter; Jach, Franziska; Karabiyik, Boris; Agrestini, Stefano; Wagner, Frank-R.; Ruck, Michael; Tjeng, Liu Hao; Kniep, Rüdiger
    The CN ligands in the isotypic compounds Sr3[Co(CN)3] und Ba3[Co(CN)3] have lost their "innocence" by higher reduction and weakening of the C–N bond, for the first time. For cobalt a closed-shell (d10)-configuration was determined. The resulting mesomeric structures of the trigonal-planar complex anions, [Co1–(CN)2(CN)3–]6–, open new insight into the chemistry of metalates and coordination compounds of transition metals with CN ligands. Finally, consequences on the chemistry of carbonylmetalates can be expected, too.
  • Zero resistance by magnetism

    2011 Stockert, Oliver; Arndt, Julia; Jeevan, Hirale S.; Geibel, Christoph; Steglich, Frank
    The question about the origin of unconventional superconductivity is one of the central issues in current condensed matter physics. Within an international collaboration scientists from the Max Planck Institute for Chemical Physics of Solids discovered that magnetic interactions are responsible for the Cooper pair formation and hence for the lossless current transport. While in conventional superconductors magnetism is detrimental for superconductivity, magnetism is an essential prerequisite for superconductivity in materials displaying unconventional superconductivity.

2010

  • From alchemy towards quantum dynamics: unravelling the secret of superducting, magnetism and structural instabilities in iron pnictides

    2010 Geibel, Christoph; Jesche, Anton; Kasinathan, Deepa; Krellner, Cornelius; Leithe-Jasper, Andreas; Nicklas, Michael; Rosner, Helge; Schnelle, Walter; Thalmeier, Peter; Borrmann, Horst; Caroca-Canales, Nubia; Kaneko, Koji; Kumar, Manoj; Miclea, Corneliu Florin; Ormeci, Alim; Schmidt, Burkhard; Schwarz, Ulrich
    The relationship between superconductivity, magnetism and structure in the recently discovered Iron-pnictide superconductors is presently one of the hot topics in solid state physics. These compounds are the subject of a broad research program at the Max Planck Institute for Chemical Physics of Solids, which includes crystal growth, measurements of a large variety of physical properties, up to theoretical calculations and modeling of the electronic properties. This collaborative research resulted in a significant progress in our understanding of the physics in those systems.

2009

  • Hard-X ray photoelectron spectroscopy: New opportunities for chemical and physical analysis

    2009 Tjeng, Liu Hao; Weinen, Jonas
    The department "Physics of correlated Matters" of the Max Planck Institute for Chemical Physics of Solids in Dresden is installing a new spectrometer at the synchrotron research facility Spring8 in Japan to carry out photoemission measurements using hard x-rays. The high kinetic energies of the emitted photoelectrons provide a much increased probing depth, facilitating considerably the use of photoelectron spectroscopy for chemical analysis of a wide range of materials.

2008

  • Magnetic resonance spectroscopy as a local probe: Investigations of structure and magnetism in intermetallic compounds

    2008 Haarmann, Frank; Baenitz, Michael; Brüning, Eva; Geibel, Christoph; Goebel, Thorsten; Jegli¿, Peter; Koch, Katrin; Pecher, Oliver; Rosner, Helge; Steglich, Frank; Grin, Yuri
    The interaction of structure and magnetism of intermetallic compounds depends on the local as well as on the periodic assembly of the atoms. In order to understand the contribution of the local properties investigations by means of appropriate methods are necessary. Nuclear magnetic resonance (NMR) spectroscopy seams to by highly suited for this task.

2007

  • New phenomena in strongly correlated electron systems

    2007 Wirth, Steffen; Singh, Surjeet; Capan, Cigdem (Louisiana State University, Baton Rouge, USA); Nicklas, Michael; DiTusa, John F. (Louisiana State University, Baton Rouge, USA); Fisk, Zachary (University of California, Irvine, USA); Steglich, Frank
    Strong electronic correlations in solids may result in fascinating, yet often not fully understood phenomena. The latter include unconventional superconductivity and quantum criticality in heavy fermion metals. Here, magnetotransport measurements may shed light on the impact of antiferromagnetic spin fluctuations on these phenomena. Nonetheless, further detailed experimental and theoretical investigations are required for a more complete comprehension within this emerging field of solid state physics.

2006

  • Cu(II)-Materials – Crystal chemistry meets Magnetism

    2006 Rosner, Helge; Schnelle, Walter; Schmitt, Miriam; Janson, Oleg (St. Petersburg State University, Russland); Gerlach, Sylvia; Schmidt, Marcus; Huang, Ya-Xi; Liu, Wei; Gippius, Andrei (Moscow State University, Russland); Johannes, Michelle Dawn (NRL Washington, USA); Drechsler, Stefan-Ludwig (IFW Dresden); Richter; Johannes (Universität Magdeburg); Kniep, Rüdiger
    Low-dimensional cuprate compounds show a variety of intriguing magnetic properties. We demonstrate that a combination of electronic structure and model calculations together with experimental results and crystal-chemical considerations can provide a deep understanding of this compound family on microscopic grounds.
  • Complexity in the world of intermetallic phases

    2006 Makongo, Julien Pierre Amelie; Burkhardt, Ulrich; Prots, Yurii; Niewa, Rainer; Kreiner, Guido
    Complex metallic alloy phases are intermetallic compounds with prominent features compared to simple metallic systems. They are based on giant unit cells comprising up to more than thousands atoms per cell, hierarchical structures and inherent disorder phenomena. The characteristic features originate from a cluster substructure, which controls short and long range order as well as the physical properties.

2005

  • Filled Skutterudites – Physics and Chemistry of Iron-Antimonides of Alkali, Alkaline-Earth, and Rare-Earth Metals

    2005 Leithe-Jasper, Andreas; Schnelle, Walter; Rosner, Helge; Wirth, Steffen; Sichelschmidt, Jörg; Baenitz, Michael; Gippius, Andrei (Moscow State University, Moskau, Russland); Rabis, Annegrit; Raychaudhuri, Pratap (Tata Institute of Fundamental Research, Mumbai, Indien); Sheet, Goutam (Tata Institute of Fundamental Research, Mumbai, Indien); Burkhardt, Ulrich; Borrmann, Horst; Ramlau, Reiner; Mydosh, John A.; Steglich, Frank; Grin, Juri
    Novel ternary intermetallic compounds of iron and antimony with a crystal structure containing large cavities, which can be filled by an electropositive element, show unusual magnetic and thermal properties. A study of the chemical bonding and of the structure-properties relationship is presented.

2004

  • ZrAs1,4Se0,5 – A non-magnetic Kondo system with properties of a normal metal

    2004 Niewa, Rainer; Schmidt, Marcus; Cichorek, Tomasz; Auffermann, Gudrun; Ramlau, Reiner; Prots, Yurii; Schmidt, Ulrike; Völzke, Anja; Schulze, Katja; Burkhardt, Ulrich; Borrmann, Horst; Cardoso-Gil, Raúl; Schnelle, Walter; Schlechte, Andreas; Steglich, Frank; Kniep, Rüdiger
    ThAsSe and UAsSe represent rare examples for non-magnetic Kondo systems. For deeper insight into this behaviour a compound with the same crystal structure type from the chemical system Zr–As–Se was studied extensively in terms of chemical composition, crystal structure and electrical resistivity at low temperatures. The results indicate the unusual behaviour of ZrAs1.4Se0.5 to be connected with dynamical phenomena within the anionic substructure.

2003

  • Quantumphenomena and Superconductivity

    2003 Sparn, Günter; Gegenwart, Philipp; Sichelschmidt, Jörg; Coleman, Piers; Custers, Jeroen; Deppe, Micha; Ferstl, Julia; Geibel, Christoph; Grosche, Friedrich Malte; Neumaier, Karl; Pépin, Catherine; Steglich, Frank; Tokiwa, Yoshifumi; Trovarelli, Octavio; Voevodin, Vladimir; Wilhelm, Heribert; Yuan, Huiqiu
    All developments achieved to date in the fields of medical-, information- and sensor- technology are based on models which are well established in physics and chemistry and which reflect the state of knowledge of fundamental research until the middle of the last century. Further progress, however, seems to be possible only if we learn to understand a new state of condensed matter, which can not be described within the context of the established models. This new state is dominated by quantum phenomena. Quantum phenomena come into play, when spatial dimensions become smaller than the wavelength of light (nano-technology) or when extremely strong correlations build up among the electrons of the solid (Quantum Hall Effect, Collossal Magnetoresistance, High Temperature Superconductivity (HTSC)). Here we report two outstanding discoveries which could be particularly important for the understanding of the HTSC. At the heart of the description of HTSC lies the assumption that superconductivity is created by coupling the charge carriers via magnetic fluctuations. In CeCu2Si2, a compound whose properties are related to those of HTSC, we not only have found hints towards the existence of a magnetic coupling mechanism but furthermore, for the first time, have been able to collect evidence for the existence of an additional, completely new coupling mechanism. The second discovery concerns the physical properties of a strongly correlated electron system (YbRh2Si2) in the vicinity of the magnetic quantum critical point. In YbRh2Si2 the strongly interacting charge carriers can not be treated within the concept of weakly interacting heavy quasi particles, as it is successfully done in heavy electron metals away from quantum criticality. In contrast to hitherto models, the quasiparticles in YbRh2Si2 seem to disintegrate into a charge part (current) and a spin part (magnetism) when approaching the quantum critical point.
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