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  • 1

    Book of Abstracts

    Plenary Talks – page 2

    Oral Contributions – page 7

    Poster Contributions – page 54

    List of presenting authors – page 108

    http://superfox.como.polimi.it

  • 2

    Plenary Talks

  • 3

    Phase diagrams of Fe based superconductors

    B. Büchner

    Institut für Festkörperforschung, IFW Dresden

    Institut für Festkörperphysik, TU Dresden

    Using a broad spectrum of experimental techniques, such as NMR, µSR, ARPES, magnetometry,

    thermodynamics, x-ray diffraction, and transport measurements, we have studied the interplay between

    magnetism and superconductivity in several classes of iron pnictide superconductors. In LaO1-xFxAsFe and

    other 1111 type materials an intimate interplay between magnetism and electronic properties is evident.

    Moreover, measurements of the electrical field gradient by NQR yield clear-cut evidence for nanoscale order

    of charges and/or orbitals which are reminiscent to the famous stripe order found in cuprates. The phase

    diagram of Co doped NaFeAs is qualitatively very similar to that of the 1111 and 122 type pnictides. In

    contrast, LiFeAs, a second member of the 111 type pnictide shows quite different behaviour. From our

    measurements on pristine material as well as hole and electron doped compounds we do not find any

    evidence for strong antiferromagnetic correlations. Instead, measurements of NQR, µSR, magnetisation and

    magnetic resonance reveal a weak ferromagnetic order in hole doped LiFeAs. Based on our determination of

    the phase diagram and the results from spectroscopic studies the possible relationship between this unusual

    ferromagnetic state and superconductivity in stoichiometric LiFeAs is discussed.

  • 4

    Filamentary superconductivity in Sr_2RuO_4-Ru eutectics - features of topology

    and symmetry in a chiral p-wave superconductor

    M. Sigrist

    Institute for Theoretical Physics, ETH Zurich, Zurich, Switzerland

    Strong evidence for chiral p-wave pairing in Sr2RuO4, a pairing state analogous to the A-phase of superfluid

    He-3, has accumulated over the past decade or so. In the eutectic Sr2RuO4-Ru system, characterized by

    micrometer-size Ru-metal inclusions, inhomogeneous superconductivity is found at a temperature roughly

    twice the bulk transition temperature. The nature of this superconducting phase - called 3-Kelvin phase - is

    very likely filamentary, due to the nucleation at the interface between Sr2RuO4 and the Ru-inclusions. The

    path from the first nucleation to bulk superconductivity requires a further symmetry breaking transition for

    this chiral p-wave superconductor, which at the same time involves a change of the topology of the

    filamentary phase. The realization of such a transition is consistent with experiments of the critical current

    and quasiparticle tunneling in the 3-Kelvin phase. Recent experiments measuring the Josephson effect

    between a Pb-film via Ru-inclusions to Sr2RuO4 show an anomalous temperature dependence of the

    Josephson critical current, with a rather sharp drop at the bulk Tc of Sr2RuO4. This may be explained

    assuming that the Josephson coupling of s-wave superconductivity (Pb - Ru) to the chiral p-wave state leads

    to phase frustration which limits the critical current. In this presentation I will give an overview on the

    present status of the phenomenological understanding of this complex superconductor.

  • 5

    Strain-engineered properties of functional oxide thin films: from bulk to free

    surfaces

    Josep Fontcuberta a , I. Fina

    a , D. Pesquera

    a , X. Martí

    a,b , V. Skumryev

    c , L. Fàbrega

    a , F. Sánchez

    a and

    G. Herranz a

    a Institut de Ciència de Materials de Barcelona (ICMAB-CSIC). Campus UAB, Bellaterra, 08193. Catalonia. Spain

    b Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5,

    121 16 Prague 2, Czech Republic

    c Institució Catalana de Recerca i Estudis Avançats (ICREA) and Departament de Física, Universitat Autònoma de

    Barcelona, 08193 Bellaterra, Catalonia Spain

    Magnetic and dielectric properties of AMO3 (M is a d n -metal) oxide perovskites are strongly dependent on

    the nature of the A-O, M-O and A-O-M bonds, the occupancy of electronic levels, the corresponding

    bandwidth and the topology of the distinct and sometimes competing, Mi-O-Mj exchange interactions.

    As a result, perovskites display an extremely rich variety of properties, ranging from ferroelectricity,

    antiferromagnetism or ferromagnetism, insulating or metallic behavior or ionic conductivity, etc, that boosts

    up their relevance in many different areas of science and technology.

    It is now known that properties can be severely modified, and emerging properties have been discovered, by

    suitable AMO3 confinement in sandwich epitaxial heterostructures or by appropriate strain-engineering.

    Here, we shall illustrate this progress by reviewing some examples of using epitaxial strain to modify: (a)

    bulk properties in multiferroic AMnO3 thin films, allowing to obtain distinct antiferromagnetic magnetic

    orders and subsequently different dielectric ground states, including the magnetically switchable ferroelectric

    polarization and (b) we will also show that epitaxial clamping across some interfaces in

    magnetic/ferroelectric heterostructures provides an additional way to fine tuning the dielectric response. We

    will also show (c) that exploiting orbital symmetry breaking by epitaxial strain and the inherent symmetry

    breaking at free surfaces, the electron occupancy of surface 3d-orbitals can be tailored at wish. Some

    implications of these findings will be discussed.

  • 6

    Novel Two-dimensional Electron Systems at Oxide Interfaces

    J. Mannhart

    Max Planck Institute for Solid State Research

    Stuttgart, Germany

    Two-dimensional electron gases based on conventional semiconductors such as Si or GaAs play a

    pivotal role in fundamental science and technology. The high mobilities achieved enabled the discovery of

    the integer and fractional quantum Hall effects and are exploited in high-electron-mobility transistors.

    Recent work has shown that two-dimensional electron systems can also exist at oxide interfaces [1].

    These electron systems are characterized by properties that fundamentally differ from those of

    semiconductor interfaces. In the presentation I will provide an overview of our studies of these surprising

    electronic systems (see, e.g., [2,3]) and explore the potential of electron liquids at oxide interfaces for the use

    in nanoscale electronic devices.

    [1] A. Ohtomo et al., Nature 419, 378 (2002)

    [2] N. Reyren et al., Science 317, 1196 (2007)

    [3] J. Mannhart and D.G. Schlom, Science 327, 1607 (2010)

  • 7

    Oral Contributions

  • 8

    Iron-based superconductor: Improving global critical current in the FeSeTe

    polycrystalline samples

    A.Sala

    1,2 , A.Palenzona

    1,3 , C. Bernini

    3 , V. Braccini

    3 , M.R.Cimberle

    4 , C.Ferdeghini

    3 , G. Lamura

    3 ,

    A.Martinelli 3 , I. Pallecchi

    3 , G. Romano

    3 , M.Tropeano

    1,3 , R.Fittipaldi

    5 , A.Vecchione

    5 and

    M. Putti 2,3

    1 Chemistry and Industrial Chemistry Department, University of Genova, via Dodecaneso 31, I-16146 Genova, Italy 2

    Physics Department, University of Genova, via Dodecaneso 33, I-16146 Genova, Italy

    3 CNR-SPIN-Genova corso Perrone 24, 16152, Genova, Italy

    4 CNR-IMEM Physics Department, University of Genova, via Dodecaneso 33, I-16146 Genova, Italy

    5 CNR-SPIN-Salerno and Physics Department University of Salerno, Via Ponte don Melillo, I-84084 Fisciano (SA),

    Italy

    Since the discovery of the superconductivity in layered iron-based compounds by the Hosono’s

    group, a lot of different families has been discovered, all characterized by layers of iron atoms. This

    discovery was interesting because the magnetism has been considered an antagonist of superconductivity,

    oppositely in these compounds it seems to be a fundamental requirements. These kinds of compounds are

    very interesting for the understanding of the interplay between magnetisms and superconductivity.

    At the same times they can also promising for applications. Indeed they have characteristics in common with

    other technological superconductors like high temperature superconducting cuprates (HTS) and MgB2.

    The iron-based superconductors show an extraordinary high upper critical field and strong pinning, in

    addition critical current is rather independent of the field like in HTS.

    At the same time the critical current density shows low anisotropy in respect to the crystalline directions, as

    in the case of MgB2, which allows the current flow along the c-axis.

    These characteristics make the iron-based superconductors good candidates for applications in the

    generations of h

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