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Euchner H.,University of Stuttgart | Euchner H.,Grenoble Institute of Technology | Euchner H.,Vienna University of Technology | Pailhes S.,French National Center for Scientific Research | And 16 more authors.
Materials Research Society Symposium Proceedings | Year: 2013

Complex Metallic Alloys (CMAs) are metallic solids of high structural complexity, consisting of large numbers of atoms in their unit cells. Consequences of this structural complexity are manifold and give rise to a variety of exciting physical properties. The impact that such structural complexity may have on the lattice dynamics will be discussed. The surprising dynamical flexibility of Tsai-type clusters with the symmetry breaking central tetrahedron will be addressed for Zn6Sc, while in the Ba-Ge-Ni clathrate system the dynamics of encaged Ba guest atoms in the surrounding Ge-Ni host framework is analysed with respect to the experimentally evidenced strong reduction of lattice thermal conductivity. For both systems experimental results from neutron scattering are analyzed and interpreted on atomistic scale by means of ab initio and molecular dynamics simulations, resulting in a picture with the respective structural building blocks as the origin of the peculiarities in the dynamics. © 2013 Materials Research Society.


Lang M.,Goethe University Frankfurt | Tsui Y.,Goethe University Frankfurt | Tsui Y.,University of Southampton | Wolf B.,Goethe University Frankfurt | And 8 more authors.
Journal of Low Temperature Physics | Year: 2010

We report low-temperature magnetization measurements on a copper-containing coordination polymer [Cu(μ-C 2O 4)(4-aminopyridine) 2(H 2O)] n . According to these measurements and previous results (Prokofiev et al. in Cryst. Res. Technol. 42, 394, 2007), the material is a very good realization of an S=1/2 antiferromagnetic Heisenberg chain with a small saturation field B s =4.2 T, which marks the endpoint of a quantum-critical line in the B-T plane. Measurements of the magnetocaloric effect at low temperatures T=0.47 K across the saturation field yields a very large magnetothermal response with a characteristic sign change close to the quantum-critical point. The data are in good agreement with the quantum-critical behavior calculated on the basis of exact diagonalization and quantum Monte Carlo simulations. © 2010 Springer Science+Business Media, LLC.


Schwarz U.,MPI fur Chemische Physik Fester Stoffe | Tence S.,MPI fur Chemische Physik Fester Stoffe | Janson O.,MPI fur Chemische Physik Fester Stoffe | Koz C.,MPI fur Chemische Physik Fester Stoffe | And 5 more authors.
Angewandte Chemie - International Edition | Year: 2013

The first binary phase in the system Co-Bi was obtained by high-pressure high-temperature synthesis. The NiBi3-type structure motif comprises cobalt-centered monocapped bismuth prisms with covalent Co-Bi interactions. The polyhedra are condensed into infinite columns (see picture), which are arranged in the form of a distorted hexagonal rod packing. The new compound is a superconductor with a Tc slightly below 0.5 K. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Munzer W.,TU Munich | Neubauer A.,TU Munich | Adams T.,TU Munich | Muhlbauer S.,TU Munich | And 8 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We report a comprehensive small angle neutron scattering study of the magnetic phase diagram of the doped semiconductor Fe1-x Cox Si for x=0.2. For magnetic field parallel to the neutron beam we observe a sixfold intensity pattern under field cooling. The regime of the skyrmion lattice is highly hysteretic and extents over a wide temperature range as may be expected due to the site disorder of the Fe and Co atoms. Our study identifies Fe1-x Cox Si as the second material in which a skyrmion lattice forms and establishes that skyrmion lattices exist also in doped semiconductors. © 2010 The American Physical Society.


Weitzer F.,University of Vienna | Schnelle W.,MPI fur Chemische Physik Fester Stoffe | Hiebl K.,University of Vienna | Schuster J.C.,University of Vienna
Monatshefte fur Chemie | Year: 2012

The effects of cobalt additions to Fe 51.7Ni 15Si 33.3 and Fe 51.7Ni 15Si 33.3 on phase stability and magnetic properties of the soft magnetic phase h-(Fe,Ni) 2Si are explored. The addition of 5 at.% Co increases the temperature of the eutectoid decomposition of the h-phase from 738 to 760 °C as well as Curie temperatures and magnetic saturation, while the coercive field is reduced. Lattice parameter measurements indicate magnetostriction. © 2012 Springer-Verlag.

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