P. Verges

Leibniz Institute for Solid State and Materials Research Dresden, Dresden, Saxony, Germany

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Publications (67)90.96 Total impact

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    ABSTRACT: We have proposed to build a 100 T/10 ms, 70 T/100 ms, 60 T/1 s pulsed field user facility with a 50 MJ capacitor bank at the Forschungszentrum Rossendorf near Dresden. This would provide the appealing possibility to have access to Zeeman energies in the energy range of the infrared free-electron-lasers (5 μm to 150 μm; 2 ps; cw; > 10 W) now under construction at the radiation source ELBE (superconducting electron linear accelerator; 40 MeV; 1 mA; 2 ps; cw) in Rossendorf. The work is accompanied by computer simulations of the planned coil systems, of the power supply, and by the development of high-strength conductors aiming at a tensile strength of about 1.5 GPa at σ ≈ σ Cu/2 (microcomposite CuAg alloys and Cu-steel macro compounds). With a view of gaining experience in the construction and operation of pulsed magnets, a pilot pulsed field laboratory was established at the Institute of Solid State and Materials Research Dresden (IFW Dresden). The laboratory includes short pulse magnets with peak field up to 60 T in a 24 mm bore and a rise time of about 10 ms (coil from NHMFL, Tallahassee), and a 40 T long pulse magnet with 24 mm bore and rise time of about 80 ms (coil from METIS, Leuven). The repetition rate of 20 min between pulses is limited by the cooling time of the coils. The coils are energized by a 1 MJ, 10 kV capacitor bank with some special features. With this set-up measurements of magnetization and magnetotransport on 4f-electron systems, for example RECu2, have been out in the temperature range of 1.5 to 300 K and at fields up to 52 T using high precision pick-up coils.
    Full-text · Article · Jan 2012 · International Journal of Modern Physics B
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    No preview · Article · Sep 2010 · ChemInform
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    ABSTRACT: The trapped field properties of bulk melt-textured YBCO material were investigated at different temperatures. In the temperature range of liquid nitrogen, maximum trapped fields of 1.1 T were found at 77 K by doping of YBCO with small amounts of zinc. The improved pinning of zinc-doped YBa2Cu3O7−x (YBCO) results in a pronounced peak effect in the field dependence of the critical current density. the trapped field at lower temperatures increases due to the increasing critical current density, however, at temperatures around 50 K cracking of the material is observed which is exposed to considerably tensile stresses due to Lorentz forces. Very high trapped fields up to 14.4 T were achieved at 22.5 K for a YBCO disk pair by the addition of silver improving the tensile strength of YBCO and by using a bandage made of a steel tube. The steel tube produces a compressive stress on YBCO after cooling down from 300 K to the measuring temperature, which is due to the higher coeeficient of thermal expansion of steel compared with that of YBCO in the a,b plane. The application of superconducting permanent magnets with trapped fields of 10 T and more in superconducting bearings would allow to obtain very high levitation pressures up to 2500 N/cm2 which is two orders of magnitude higher than the levitation pressure achievable in superconducting bearings with conventional permanent magnets. The most important problem for the application of superconducting permanent magnets is the magnetizing procedure of the YBCO material. Results of magnetizing YBCO disks by using of pulsed magnetic fields will be presented.
    No preview · Chapter · Oct 2007
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    ABSTRACT: The zero-field muon spin relaxation (ZF-μSR) technique is employed to study the magnetic properties of the non-superconducting borocarbide SmNi2B2C. Coherent ordering of the Sm electronic magnetic moments appears below 9.86(3) K, leading to a local field at the muon site of 1056.2(2) G at 3.3 K. Measurements on superconducting YNi2B2C reveal no evidence of either slowing-down of fluctuating or the presence of quasi-static Ni electronic moments down to 3 K.
    Full-text · Article · Jul 2007 · EPL (Europhysics Letters)
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    C Beyer · O De Haas · P Verges · L Schultz
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    ABSTRACT: This paper will deliver insight into technology and physics of the levitation system for the SupraTrans project, a prototype of a superconducting transportation system. The technology used herein bases on the flux pinning in melt-textured bulk YBa2Cu3O7−X (YBCO) that stabilizes the lateral and the vertical position of the vehicle above the magnetic track. A track made from permanent magnets and soft magnetic steel-yokes acting as flux collectors has been designed and its capability is presented. The concept also includes a fast electromagnetic turnout switch to establish a highly branched transportation network. .
    Full-text · Article · Jun 2006 · Journal of Physics Conference Series

  • No preview · Conference Paper · Aug 2005
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    ABSTRACT: SupraTrans is an innovative transportation concept based on the principle of superconductive magnetic levitation. The aim of the project is to create a fully working prototype, which proves its ability for passenger transport by explicit consideration of the compatibility between systems for propulsion, safety, positioning, power supply, transport logistics and the levitation system itself. The SupraTrans technology uses the flux pinning in high temperature superconductors (HTS) to stabilize the lateral and vertical position of the vehicle on the magnetic track. This self-stabilizing system is the main advantage of the superconductive levitation in comparison to all other levitation systems, which need electronic control and power to keep a constant distance between the train and the track.
    Full-text · Article · Jul 2005 · IEEE Transactions on Applied Superconductivity
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    ABSTRACT: After the levitation force relaxation was studied for different field-cooling height and working-levitation height, the high-temperature superconductor (HTS) bulk was horizontally moved in the lateral direction above the permanent magnet guideway. Both levitation and guidance force were collected by the measurement system at the same time. It was found that the decay of levitation force is dependent on both the maximum lateral displacement and the movement cycle times, while the guidance force hysteresis curve does not change after the first cycle. This work provided scientific analysis for the HTS maglev system design.
    No preview · Article · May 2005 · Applied Physics Letters
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    ABSTRACT: The magnetoresistance (MR) of cold-pressed powder pellets of the half-metallic ferromagnet CrO2 was measured in wide ranges of temperature T and magnetic fields H up to μ0H=16 T. The MR increases from 2% at 300 K up to 64% at T=1.5 K and no saturation is observed up to 16 T. The low field resistivity depends logarithmically on temperature whereas the high-field MR shows a scaling behavior with H/T. The results favor second-order tunneling (paramagnetic assisted tunneling) at zero bias via localized magnetic moments at or within the barrier between the CrO2 grains as the dominant resistivity mechanism for both the low- and high-field MR, respectively.
    No preview · Article · Apr 2005 · Journal of Magnetism and Magnetic Materials
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    C Beyer · P Verges · O De Haas · L Schultz
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    ABSTRACT: Acknowledgments This work was funded by the Sächsische Aufbaubank (SAB) and Sächsisches Staatsministerium für Wirtschaft und Arbeit (SMWA). Acknowledgments also to G. Krabbes for providing bulk YBCO material, to W. Pfeiffer for the link to industrial partners and to T. Riederich for the laboratory and measurement support. Abstract This paper will deliver insight into technology and physics of the levitation system for the SupraTrans project, a prototype of a superconducting transportation system. The technology used herein bases on the flux pinning in melt-textured bulk YBCO that stabilizes the lateral and the vertical position of the vehicle above the magnetic track. A track made from permanent magnets and soft magnetic steel-yokes acting as flux collectors has been designed and its capability is presented. The concept also includes a fast electromagnetic turnout switch to establish a highly branched transportation network.
    Full-text · Article · Jan 2004
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    L. Shlyk · G. Krabbes · G. Fuchs · K. Nenkov · P. Verges
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    ABSTRACT: The pinning forces and trapped fields obtained in bulk YBa2Cu3O7 based material doped with Li are compared with results reported for melt-processed samples doped with Zn. The increase of the volume pinning force of Li doped material is twice that of Zn doped YBCO at 77 K. This leads to 20% higher magnetic fields trapped in the Li-doped sample at 77 K. The measurements of the magnetic relaxation at a field of 1 T reveals that the activation energy above 65 K is higher for the Li-doped sample indicating that Li impurities are more effective in increasing the pinning energy.
    Preview · Article · Oct 2003 · Physica C Superconductivity
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    ABSTRACT: We report on the temperature dependence of the maximum trapped field B o(T) in the high-T c superconductor YBa2Cu3O7–x (YBCO). Trapped fields of bulk melt-textured YBCO samples are limited by their pinning behaviour and mechanical properties. The mechanical properties of bulk YBCO samples were improved by the addition of silver. Furthermore, the YBCO disks were encapsulated in steel tubes in order to reinforce the material against the large tensile stress acting during the magnetizing process. High trapped fields up to 13.3 T were measured at 33 K on the surface of a single YBCO disk containing Ag additions and reinforced with steel tubes. The flux pinning properties of this YBCO disk were improved by neutron irradiation and Zn doping resulting in a significant shift of the trapped field curve B o(T) to higher temperatures. In YBCO mini-magnets, consisting of two YBCO disks, maximum trapped fields up to 16.0 T were achieved at 24 K by a combination of Zn-doping and Ag addition. The improved reinforcement, which was used in this case, was found to withstand the maximum trapped field of 16 T without cracking.
    No preview · Article · Sep 2003 · Journal of Low Temperature Physics
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    ABSTRACT: We report on the temperature dependence of the trapped field in neutron irradiated YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> bulk melt-textured materials. The field trapping capability of these materials at low temperatures is limited by their mechanical properties. We observe that samples without reinforcement usually break during activation at temperatures of around 50 K. Two reinforcement techniques were tested. Resin impregnation is found to be less effective than stainless steel bandaging to compensate for the magnetic stress generated during activation. The resin impregnated samples crack during activation at temperatures of around 45 K. Stainless steel bandaging improves the mechanical properties of the YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> samples and trapped fields of up to 13.3 T were achieved at 33 K.
    No preview · Article · Jul 2003 · IEEE Transactions on Applied Superconductivity
  • L. Shlyk · G. Krabbes · G. Fuchs · K. Nenkov · P. Verges
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    ABSTRACT: The pinning forces and trapped fields obtained in bulk YBa <sub>2</sub> Cu <sub>3</sub> O <sub>7</sub> (YBCO)-based material doped with Li are compared with results reported for melt-processed samples doped with Zn. The increase of the volume pinning force of Li doped material is twice that of Zn doped YBCO at 77 K. This leads to 20% higher magnetic fields trapped in the Li-doped sample at 77 K. © 2002 American Institute of Physics.
    No preview · Article · Jan 2003 · Applied Physics Letters
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    ABSTRACT: A novel magnetic pair-making interaction between Mn and Ru shows a strong correlation between the magnetic ordering and electronic transport, which was well exemplified in the investigation of bulk polycrystalline samples of La0.7Pb0.3Mn1⊟xRuxO3 and La0.6Pb0.4Mn1⊟xRuxO3, where 0.0 ≤ x ≤ 0.4. The metal-insulator transition (Tρ) complementing the Curie temperature (Tc) was observed up to 30% of Ru in La0.7Pb0.3Mn1⊟xRuxO3, and extended up to 40% of Ru in La0.6Pb0.4Mn1⊟xRuxO3, showing a unique double-exchange ferromagnetic exchange interaction between Mn and Ru ions. An upturn in resistance due to charge carrier localization at low temperatures (T<0.5 Tc) for more than 20% Ru doping was due to a dominant hole carrier density contribution rather than to grain boundary effects as inferred from the scanning electron microscopy and energy dispersive x-ray studies of the samples sintered at 1200 and 1400 °C. The charge localization effect of the eg electrons was removed by tuning the hole carrier density as demonstrated in the La0.6Pb0.4Mn1⊟xRuxO3 samples. Long range correlations between magnetism and transport in this series was attributed to the presence of mixed valence Ru(IV/V) and Mn(III)/(IV) pair, which shows a unique double exchange mediated interaction.
    No preview · Article · Dec 2002
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    G Krabbes · G Fuchs · P Verges · P Diko · G Stöver · S Gruss
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    ABSTRACT: The maximum field B0=16 T was trapped at 24 K in the gap of a mini-magnet made of two cylindrical samples. B0 on top of a single cylinder was 12.5 T at 20 K and 9 T at 40 K. The YBa2Cu3O7 based bulk material was prepared by the modified melt crystallization process from Y123+Y200 (+Pt) precursor with 12 wt.% Ag forming silver precipitates in the as grown materials. A bandage of stainless steel compensated the tensile stress during magnetization. The unfavorable influence of admixed Ag on the critical current density jc was compensated by doping with Zn ions.
    Full-text · Article · Oct 2002 · Physica C Superconductivity
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    ABSTRACT: We have proposed to build a 100 T/10 ms, 70 T/100 ms, 60 T/1 s pulsed field user facility with a 50 MJ capacitor bank at the Forschungszentrum Rossendorf near Dresden. This would provide the appealing possibility to have access to Zeeman energies in the energy range of the infrared free-electron-lasers (5 mm to 150 mm; 2 ps; cw; > 10 W) now under construction at the radiation source ELBE (superconducting electron linear accelerator; 40 MeV; 1 mA; 2 ps; cw) in Rossendorf. The work is accompanied by computer simulations of the planned coil systems, of the power supply, and by the development of high-strength conductors aiming at a tensile strength of about 1.5 GPa at s » sCu/2 (microcomposite CuAg alloys and Cu-steel macro compounds). With a view of gaining experience in the construction and operation of pulsed magnets, a pilot pulsed field laboratory was established at the Institute of Solid State and Materials Research Dresden (IFW Dresden). The laboratory includes short pulse magnets with peak field up to 60 T in a 24 mm bore and a rise time of about 10 ms (coil from NHMFL, Tallahassee), and a 40 T long pulse magnet with 24 mm bore and rise time of about 80 ms (coil from METIS, Leuven). The repetition rate of 20 min between pulses is limited by the cooling time of the coils. The coils are energized by a 1 MJ, 10 kV capacitor bank with some special features. With this set-up measurements of magnetization and magnetotransport on 4f-electron systems, for example RECu2, have been out in the temperature range of 1.5 to 300 K and at fields up to 52 T using high precision pick-up coils.
    Full-text · Article · Aug 2002 · International Journal of Modern Physics B
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    G Fuchs · S Gruss · P Verges · G Krabbes · K.-H Müller · J Fink · L Schultz
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    ABSTRACT: Trapped fields up to 16 T were achieved at 24 K in superconducting mini-magnets consisting of two bulk YBCO disks. The YBCO disks were encapsulated in steel tubes in order to reinforce the material against the large tensile stress acting during the magnetizing process and to avoid cracking of the material. Additionally, Ag and Zn additions were used for improving the mechanical and the pinning properties of the superconductor, respectively.
    Full-text · Article · Aug 2002 · Physica C Superconductivity
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    ABSTRACT: We report on very high trapped fields (13.3 T at 33 K) achieved in bulk YBa2Cu3O7−δ melt-textured monoliths, which were reinforced by steel tubes to compensate the tensile stress generated during activation. The flux pinning properties were improved by neutron irradiation. The resulting increase of the critical current density shifts the maximum attainable trapped fields to higher temperatures (by about 10 K). © 2002 American Institute of Physics.
    No preview · Article · Jul 2002 · Applied Physics Letters
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    ABSTRACT: Improved trapped fields are reported for bulk melt-textured YBa <sub> 2 </sub> Cu <sub> 3 </sub> O <sub>7-δ</sub> (YBCO) material in the temperature range between 20 and 50 K. Trapped fields up to 12.2 T were obtained at 22 K on the surface of single YBCO disks (with Ag and Zn additions). In YBCO minimagnets, maximum trapped fields of 16 T (at 24 K) and of 11,2 T (at 47 K) were achieved using ( Zn+Ag ) and Zn additions, respectively. In all cases, the YBCO disks were encapsulated in steel tubes in order to reinforce the material against the large tensile stress acting during the magnetizing process and to avoid cracking. We observed cracking not only during the magnetizing process, but also as a consequence of flux jumps due to thermomagnetic instabilities in the temperature range betweeen 20 and 30 K. © 2001 American Institute of Physics.
    Full-text · Article · Dec 2001 · Applied Physics Letters

Publication Stats

931 Citations
90.96 Total Impact Points

Institutions

  • 1996-2006
    • Leibniz Institute for Solid State and Materials Research Dresden
      • • Institute for Metallic Materials
      • • Institute for Solid State Research
      Dresden, Saxony, Germany
  • 2002
    • Technische Universität Dresden
      • Institute of Applied Computer Science
      Dresden, Saxony, Germany
  • 2001
    • Helmholtz-Zentrum Dresden-Rossendorf
      Dresden, Saxony, Germany