1
|
Kurlander L, Srinivasan A, Ghobadi A, Suser S, Doubrovina E, Boulad F, Mascarenhas L, Laquaglia M, Price A, Behr G, Shulkin B, Sudhindra A, Wei Y, Hiremath M, Navarro W, O'Reilly R, Prockop S. Efficacy and safety of tabelecleucel in patients with EpsteinBarr Virus-associated leiomyosarcomas (EBV+ LMS). Ann Oncol 2018. [DOI: 10.1093/annonc/mdy485.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
|
2
|
Seivewright H, Salkovskis P, Green J, Mullan N, Behr G, Carlin E, Young S, Goldmeier D, Tyrer P. Prevalence and service implications of health anxiety in genitourinary medicine clinics. Int J STD AIDS 2016; 15:519-22. [PMID: 15307961 DOI: 10.1258/0956462041558122] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A comparison of the prevalence of health anxiety in genitourinary medicine (GUM) clinics in two UK centres was carried out using a new rating scale, the Health Anxiety Inventory (HAI). The relationship of health anxiety to demographic and clinical variables, and its impact on service contacts, was also examined in one of these centres. 694 patients were assessed and significant health anxiety was identified in 8–11%. HAI scores were stable over time and high levels persisted in the absence of treatment. Attenders with sexually transmitted infections had significantly lower levels of health anxiety than those with other conditions. Contacts with clinic doctors and health advisors in the nine months before and after assessment were significantly greater in those with high health anxiety, with doctor appointments 37% higher in the high HAI group ( P = 0.005). Health anxiety is a source of considerable morbidity in GUM clinics deserving further study.
Collapse
Affiliation(s)
- H Seivewright
- Department of Psychological Medicine, Imperial College (Charing Cross Campus), London W6 8RP, UK.
| | | | | | | | | | | | | | | | | |
Collapse
|
3
|
Johnston S, Monney C, Bisogni V, Zhou KJ, Kraus R, Behr G, Strocov VN, Málek J, Drechsler SL, Geck J, Schmitt T, van den Brink J. Electron-lattice interactions strongly renormalize the charge-transfer energy in the spin-chain cuprate Li2CuO2. Nat Commun 2016; 7:10563. [PMID: 26884151 PMCID: PMC4757783 DOI: 10.1038/ncomms10563] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 12/26/2015] [Indexed: 11/09/2022] Open
Abstract
Strongly correlated insulators are broadly divided into two classes: Mott-Hubbard insulators, where the insulating gap is driven by the Coulomb repulsion U on the transition-metal cation, and charge-transfer insulators, where the gap is driven by the charge-transfer energy Δ between the cation and the ligand anions. The relative magnitudes of U and Δ determine which class a material belongs to, and subsequently the nature of its low-energy excitations. These energy scales are typically understood through the local chemistry of the active ions. Here we show that the situation is more complex in the low-dimensional charge-transfer insulator Li2CuO2, where Δ has a large non-electronic component. Combining resonant inelastic X-ray scattering with detailed modelling, we determine how the elementary lattice, charge, spin and orbital excitations are entangled in this material. This results in a large lattice-driven renormalization of Δ, which significantly reshapes the fundamental electronic properties of Li2CuO2.
Collapse
Affiliation(s)
- Steve Johnston
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Claude Monney
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232, Villigen, Switzerland.,Department of Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Valentina Bisogni
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstrasse 20, D-01171 Dresden, Germany.,National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - Ke-Jin Zhou
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232, Villigen, Switzerland.,Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Roberto Kraus
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstrasse 20, D-01171 Dresden, Germany
| | - Günter Behr
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstrasse 20, D-01171 Dresden, Germany
| | - Vladimir N Strocov
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232, Villigen, Switzerland
| | - Jiři Málek
- Institute of Physics, ASCR, Na Slovance 2, CZ-18221 Praha 8, Czech Republic
| | - Stefan-Ludwig Drechsler
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstrasse 20, D-01171 Dresden, Germany
| | - Jochen Geck
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstrasse 20, D-01171 Dresden, Germany
| | - Thorsten Schmitt
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232, Villigen, Switzerland
| | - Jeroen van den Brink
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstrasse 20, D-01171 Dresden, Germany.,Department of Physics, TU Dresden, D-01062 Dresden, Germany
| |
Collapse
|
4
|
Monney C, Bisogni V, Zhou KJ, Kraus R, Strocov VN, Behr G, Málek J, Kuzian R, Drechsler SL, Johnston S, Revcolevschi A, Büchner B, Rønnow HM, van den Brink J, Geck J, Schmitt T. Determining the short-range spin correlations in the spin-chain Li2CuO2 and CuGeO3 compounds using resonant inelastic x-ray scattering. Phys Rev Lett 2013; 110:087403. [PMID: 23473202 DOI: 10.1103/physrevlett.110.087403] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Indexed: 06/01/2023]
Abstract
We report a high-resolution resonant inelastic soft x-ray scattering study of the quantum magnetic spin-chain materials Li(2)CuO(2) and CuGeO(3). By tuning the incoming photon energy to the oxygen K edge, a strong excitation around 3.5 eV energy loss is clearly resolved for both materials. Comparing the experimental data to many-body calculations, we identify this excitation as a Zhang-Rice singlet exciton on neighboring CuO(4) plaquettes. We demonstrate that the strong temperature dependence of the inelastic scattering related to this high-energy exciton enables us to probe short-range spin correlations on the 1 meV scale with outstanding sensitivity.
Collapse
Affiliation(s)
- Claude Monney
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Yavaş H, van Veenendaal M, van den Brink J, Ament LJP, Alatas A, Leu BM, Apostu MO, Wizent N, Behr G, Sturhahn W, Sinn H, Alp EE. Observation of phonons with resonant inelastic x-ray scattering. J Phys Condens Matter 2010; 22:485601. [PMID: 21406750 DOI: 10.1088/0953-8984/22/48/485601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Phonons, the quantum mechanical representation of lattice vibrations, and their coupling to the electronic degrees of freedom are important for understanding thermal and electric properties of materials. For the first time, phonons have been measured using resonant inelastic x-ray scattering (RIXS) across the Cu K-edge in cupric oxide (CuO). Analyzing these spectra using an ultra-short core-hole lifetime approximation and exact diagonalization techniques, we can explain the essential inelastic features. The relative spectral intensities are related to the electron-phonon coupling strengths.
Collapse
Affiliation(s)
- H Yavaş
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Borisenko SV, Zabolotnyy VB, Evtushinsky DV, Kim TK, Morozov IV, Yaresko AN, Kordyuk AA, Behr G, Vasiliev A, Follath R, Büchner B. Superconductivity without nesting in LiFeAs. Phys Rev Lett 2010; 105:067002. [PMID: 20867999 DOI: 10.1103/physrevlett.105.067002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Indexed: 05/29/2023]
Abstract
We have studied the electronic structure of the nonmagnetic LiFeAs (T(c)∼18 K) superconductor using angle-resolved photoemission spectroscopy. We find a notable absence of the Fermi surface nesting, strong renormalization of the conduction bands by a factor of 3, high density of states at the Fermi level caused by a van Hove singularity, and no evidence for either a static or a fluctuating order except superconductivity with in-plane isotropic energy gaps. Our observations suggest that these electronic properties capture the majority of ingredients necessary for the superconductivity in iron pnictides.
Collapse
Affiliation(s)
- S V Borisenko
- Leibniz-Institute for Solid State Research, IFW-Dresden, D-01171 Dresden, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Inosov DS, White JS, Evtushinsky DV, Morozov IV, Cameron A, Stockert U, Zabolotnyy VB, Kim TK, Kordyuk AA, Borisenko SV, Forgan EM, Klingeler R, Park JT, Wurmehl S, Vasiliev AN, Behr G, Dewhurst CD, Hinkov V. Weak superconducting pairing and a single isotropic energy gap in stoichiometric LiFeAs. Phys Rev Lett 2010; 104:187001. [PMID: 20482200 DOI: 10.1103/physrevlett.104.187001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2010] [Indexed: 05/29/2023]
Abstract
We report superconducting (SC) properties of stoichiometric LiFeAs (T(c)=17 K) studied by small-angle neutron scattering (SANS) and angle-resolved photoemission (ARPES). Although the vortex lattice exhibits no long-range order, well-defined SANS rocking curves indicate better ordering than in chemically doped 122 compounds. The London penetration depth lambda(ab)(0)=210+/-20 nm, determined from the magnetic field dependence of the form factor, is compared to that calculated from the ARPES band structure with no adjustable parameters. The temperature dependence of lambda(ab) is best described by a single isotropic SC gap Delta(0)=3.0+/-0.2 meV, which agrees with the ARPES value of Delta(0)(ARPES)=3.1+/-0.3 meV and corresponds to the ratio 2Delta/k(B)T(c)=4.1+/-0.3, approaching the weak-coupling limit predicted by the BCS theory. This classifies LiFeAs as a weakly coupled single-gap superconductor.
Collapse
Affiliation(s)
- D S Inosov
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Lang G, Grafe HJ, Paar D, Hammerath F, Manthey K, Behr G, Werner J, Büchner B. Nanoscale electronic order in iron pnictides. Phys Rev Lett 2010; 104:097001. [PMID: 20367004 DOI: 10.1103/physrevlett.104.097001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Indexed: 05/29/2023]
Abstract
The charge distribution in RFeAsO1-xFx (R=La,Sm) iron pnictides is probed using As nuclear quadrupole resonance. Whereas undoped and optimally doped or overdoped compounds feature a single charge environment, two charge environments are detected in the underdoped region. Spin-lattice relaxation measurements show their coexistence at the nanoscale. Together with the quantitative variations of the spectra with doping, they point to a local electronic order in the iron layers, where low- and high-doping-like regions would coexist. Implications for the interplay of static magnetism and superconductivity are discussed.
Collapse
Affiliation(s)
- G Lang
- IFW Dresden, Institute for Solid State Research, P.O. Box 270116, D-01171 Dresden, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Abstract
Abstract
An incommensurately modulated structure of CeSi1.82 as determined by single-crystal X-ray diffraction at room temperature is reported. The observed satellite reflections reduce the orthorhombic symmetry of the X-ray pattern to a monoclinic one. This suggests the description of the modulated structure in the monoclinic superspace group I2/b(αβ0)00. The modulation wave vector was determined to q = 0.410(1) · a* + 0.610(1) · b*. The refinement was done using harmonic modulation functions for the displacement and the occupation probability of the atoms, the quality parameters converged to R
obs = 3.33% (R
obs = 2.56% for the main reflections, R
obs = 8.88% for the 1st order satellite reflections and R
obs = 33.06% for the 2nd order satellite reflections). The origin of the observed satellite reflections is attributed to a modulation of the partly occupied Si site caused by composition changes within the crystal.
Collapse
|
10
|
Mühlbauer S, Pfleiderer C, Böni P, Laver M, Forgan EM, Fort D, Keiderling U, Behr G. Morphology of the superconducting vortex lattice in ultrapure niobium. Phys Rev Lett 2009; 102:136408. [PMID: 19392383 DOI: 10.1103/physrevlett.102.136408] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Indexed: 05/27/2023]
Abstract
The morphology of the superconducting flux line lattice (FLL) of Nb comprises gradual variations with various lock-in transitions and symmetry breaking rotations. We report a comprehensive small-angle neutron scattering study of the FLL in an ultrapure single crystal of Nb as a function of the orientation of the applied magnetic field. We attribute the general morphology of the FLL and its orientation to three dominant mechanisms; first, nonlocal contributions, second, the transition between open and closed Fermi surface sheets and, third, the intermediate mixed state between the Meissner and the Shubnikov phase.
Collapse
Affiliation(s)
- S Mühlbauer
- Technische Universität München, Physik Department E21, D-85748 Garching, Germany
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Luetkens H, Klauss HH, Kraken M, Litterst FJ, Dellmann T, Klingeler R, Hess C, Khasanov R, Amato A, Baines C, Kosmala M, Schumann OJ, Braden M, Hamann-Borrero J, Leps N, Kondrat A, Behr G, Werner J, Büchner B. The electronic phase diagram of the LaO(1-x)F(x)FeAs superconductor. Nat Mater 2009; 8:305-309. [PMID: 19234445 DOI: 10.1038/nmat2397] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Accepted: 01/20/2009] [Indexed: 05/27/2023]
Abstract
The competition of magnetic order and superconductivity is a key element in the physics of all unconventional superconductors, for example in high-transition-temperature cuprates, heavy fermions and organic superconductors. Here superconductivity is often found close to a quantum critical point where long-range antiferromagnetic order is gradually suppressed as a function of a control parameter, for example charge-carrier doping or pressure. It is believed that dynamic spin fluctuations associated with this quantum critical behaviour are crucial for the mechanism of superconductivity. Recently, high-temperature superconductivity has been discovered in iron pnictides, providing a new class of unconventional superconductors. Similar to other unconventional superconductors, the parent compounds of the pnictides show a magnetic ground state and superconductivity is induced on charge-carrier doping. In this Letter the structural and electronic phase diagram is investigated by means of X-ray scattering, muon spin relaxation and Mössbauer spectroscopy on the series LaO(1-x)F(x)FeAs. We find a discontinuous first-order-like change of the Néel temperature, the superconducting transition temperature and the respective order parameters. Our results strongly question the relevance of quantum critical behaviour in iron pnictides and prove a strong coupling of the structural orthorhombic distortion and the magnetic order both disappearing at the phase boundary to the superconducting state.
Collapse
Affiliation(s)
- H Luetkens
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Devishvili A, Rotter M, Doerr M, Beuneu B, Behr G. Magnetic structure of GdCu(6). J Phys Condens Matter 2009; 21:126002. [PMID: 21817474 DOI: 10.1088/0953-8984/21/12/126002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Hot neutron diffraction has been used to study the magnetic structure of GdCu(6). Long range antiferromagnetic order with a propagation vector of (h 0 0) has been determined below the Néel temperature T(N) = 16 K from the neutron powder refinement. The magnetic moments are oriented normal to the a direction, which is in agreement with previously reported results of bulk experiments. Mean field model calculations suggest that the magnetic structure is a helix.
Collapse
Affiliation(s)
- Anton Devishvili
- Institut Laue Langevin, Grenoble, France. Institut für Physikalische Chemie, Universität Wien, Austria
| | | | | | | | | |
Collapse
|
13
|
Inosov DS, Evtushinsky DV, Koitzsch A, Zabolotnyy VB, Borisenko SV, Kordyuk AA, Frontzek M, Loewenhaupt M, Löser W, Mazilu I, Bitterlich H, Behr G, Hoffmann JU, Follath R, Büchner B. Electronic structure and nesting-driven enhancement of the RKKY interaction at the magnetic ordering propagation vector in Gd2PdSi3 and Tb2PdSi3. Phys Rev Lett 2009; 102:046401. [PMID: 19257445 DOI: 10.1103/physrevlett.102.046401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Indexed: 05/27/2023]
Abstract
Measurements of the low-energy electronic structure in Gd2PdSi3 and Tb2PdSi3 by means of angle-resolved photoelectron spectroscopy reveal a Fermi surface consisting of an electron barrel at the Gamma point surrounded by spindle-shaped electron pockets originating from the same band. The calculated momentum-dependent RKKY coupling strength is peaked at the 1/2GammaK wave vector, which coincides with the propagation vector of the low-temperature in-plane magnetic order observed by neutron diffraction, thereby demonstrating the decisive role of the Fermi surface geometry in explaining the complex magnetic ground state of ternary rare earth silicides.
Collapse
Affiliation(s)
- D S Inosov
- Leibniz Institut für Festkörper- und Werkstoffforschung Dresden, D-01171 Dresden, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Drechsler SL, Grobosch M, Koepernik K, Behr G, Köhler A, Werner J, Kondrat A, Leps N, Hess C, Klingeler R, Schuster R, Büchner B, Knupfer M. Optical study of LaO0.9F0.1FeAs: evidence for a weakly coupled superconducting state. Phys Rev Lett 2008; 101:257004. [PMID: 19113745 DOI: 10.1103/physrevlett.101.257004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Indexed: 05/27/2023]
Abstract
We have studied the reflectance of the recently discovered superconductor LaO0.9F0.1FeAs in a wide energy range from the far infrared to the visible regime. We report on the observation of infrared active phonons, the plasma edge, and possible interband transitions. On the basis of this data and the reported in-plane penetration depth lambda{L}(0)=254 nm [H. Luetkens, Phys. Rev. Lett. 101, 097009 (2008)] a disorder sensitive relatively small value of the total electron-boson coupling constant lambda{tot}=lambda{e-ph}+lambda{e-sp} approximately 0.6+/-0.35 can be estimated adopting an effective single-band picture.
Collapse
Affiliation(s)
- S-L Drechsler
- IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Fuchs G, Drechsler SL, Kozlova N, Behr G, Köhler A, Werner J, Nenkov K, Klingeler R, Hamann-Borrero J, Hess C, Kondrat A, Grobosch M, Narduzzo A, Knupfer M, Freudenberger J, Büchner B, Schultz L. High-field pauli-limiting behavior and strongly enhanced upper critical magnetic fields near the transition temperature of an arsenic-deficient LaO0.9F0.1FeAs1-delta superconductor. Phys Rev Lett 2008; 101:237003. [PMID: 19113583 DOI: 10.1103/physrevlett.101.237003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Indexed: 05/15/2023]
Abstract
We report upper critical field Bc2(T) data for disordered (arsenic-deficient) LaO0.9F0.1FeAs1-delta in a wide temperature and magnetic field range up to 47 T. Because of the large linear slope of Bc2 approximately -5.4 to -6.6 T/K near Tc approximately 28.5 K, the T dependence of the in-plane Bc2(T) shows a flattening near 23 K above 30 T which points to Pauli-limited behavior with Bc2(0) approximately 63-68 T. Our results are discussed in terms of disorder effects within [corrected] unconventional superconducting pairings.
Collapse
Affiliation(s)
- G Fuchs
- IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Luetkens H, Klauss HH, Khasanov R, Amato A, Klingeler R, Hellmann I, Leps N, Kondrat A, Hess C, Köhler A, Behr G, Werner J, Büchner B. Field and temperature dependence of the superfluid density in LaFeAsO1-xFx superconductors: a muon spin relaxation study. Phys Rev Lett 2008; 101:097009. [PMID: 18851647 DOI: 10.1103/physrevlett.101.097009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Indexed: 05/26/2023]
Abstract
We present zero field and transverse field muon spin relaxation experiments on the recently discovered Fe-based superconductor LaFeAsO1-xFx (x=0.075 and x=0.1). The temperature dependence of the deduced superfluid density is consistent with a BCS s-wave or a dirty d-wave gap function, while the field dependence strongly evidences unconventional superconductivity. We obtain the in-plane penetration depth of lambda ab(0)=254(2) nm for x=0.1 and lambda ab(0)=364(8) nm for x=0.075. Further evidence for unconventional superconductivity is provided by the ratio of Tc versus the superfluid density, which is close to the Uemura line of high-Tc cuprates.
Collapse
Affiliation(s)
- H Luetkens
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Klauss HH, Luetkens H, Klingeler R, Hess C, Litterst FJ, Kraken M, Korshunov MM, Eremin I, Drechsler SL, Khasanov R, Amato A, Hamann-Borrero J, Leps N, Kondrat A, Behr G, Werner J, Büchner B. Commensurate spin density wave in LaFeAsO: a local probe study. Phys Rev Lett 2008; 101:077005. [PMID: 18764570 DOI: 10.1103/physrevlett.101.077005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Indexed: 05/26/2023]
Abstract
We present a detailed study on the magnetic order in the undoped mother compound LaFeAsO of the recently discovered Fe-based superconductor LaFeAsO1-xFx. In particular, we present local probe measurements of the magnetic properties of LaFeAsO by means of 57Fe Mössbauer spectroscopy and muon-spin relaxation in zero external field along with magnetization and resistivity studies. These experiments prove a commensurate static magnetic order with a strongly reduced ordered moment of 0.25(5)muB at the iron site below T(N)=138 K, well separated from a structural phase transition at T(S)=156 K. The temperature dependence of the sublattice magnetization is determined and compared to theory. Using a four-band spin density wave model both, the size of the order parameter and the quick saturation below T(N) are reproduced.
Collapse
Affiliation(s)
- H-H Klauss
- Institut für Festkörperphysik, TU Dresden, D-01069 Dresden, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Grafe HJ, Paar D, Lang G, Curro NJ, Behr G, Werner J, Hamann-Borrero J, Hess C, Leps N, Klingeler R, Büchner B. 75As NMR studies of superconducting LaFeAsO0.9F0.1. Phys Rev Lett 2008; 101:047003. [PMID: 18764358 DOI: 10.1103/physrevlett.101.047003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Indexed: 05/26/2023]
Abstract
We have performed 75As nuclear magnetic resonance measurements on aligned powders of the new LaFeAsO0.9F0.1 superconductor. In the normal state, we find a strong temperature dependence of the spin shift and Korringa behavior of the spin lattice relaxation rate. In the superconducting state, we find evidence for line nodes in the superconducting gap and spin-singlet pairing. Our measurements reveal a strong anisotropy of the spin lattice relaxation rate, which suggests that superconducting vortices contribute to the relaxation rate when the field is parallel to the c axis but not for the perpendicular direction.
Collapse
Affiliation(s)
- H-J Grafe
- IFW Dresden, Institute for Solid State Research, P.O. Box 270116, D-01171 Dresden, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Weissbach T, Leisegang T, Kreyssig A, Frontzek M, Hoffmann JU, Souptel D, Köhler A, Behr G, Paufler P, Meyer DC. Intergrowth of several solid phases from the Y–Ni–B–C system in a large YNi2B2C crystal. J Appl Crystallogr 2008. [DOI: 10.1107/s002188980801279x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A YNi2B2C single crystal containing traces of foreign phases was inspected by means of neutron and X-ray diffraction as well as scanning electron microscopy and X-ray spectroscopy methods. The diffraction patterns obtained from the experiments look similar to those expected for a superstructure. Nevertheless, they can be interpreted as crystallographically oriented precipitations of YB2C2and Ni2B within the YNi2B2C crystal, formed during the cooling process. The orientation relation between the lattices was obtained from experimental neutron and X-ray data. Structure refinements of the collected X-ray data were performed by separation of the intensity data of the individual phases. Scanning electron microscopy images of the inclusions found on a polished cross section of the crystal are presented; their chemical composition was determined using wavelength-dispersive X-ray analysis.
Collapse
|
20
|
Leisegang T, Weissbach T, Dshemuchadse J, Faulhaber E, Frontzek M, Stockert O, Souptel D, Behr G, Jeevan HS, Geibel C, Paufler P, Meyer DC. Influence of the Si content on the structure of rare-earth silicides. Acta Crystallogr A 2007. [DOI: 10.1107/s0108767307094937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
21
|
Notbohm S, Ribeiro P, Lake B, Tennant DA, Schmidt KP, Uhrig GS, Hess C, Klingeler R, Behr G, Büchner B, Reehuis M, Bewley RI, Frost CD, Manuel P, Eccleston RS. One- and two-triplon spectra of a cuprate ladder. Phys Rev Lett 2007; 98:027403. [PMID: 17358648 DOI: 10.1103/physrevlett.98.027403] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Indexed: 05/14/2023]
Abstract
We have performed inelastic neutron scattering on the near ideal spin-ladder compound La4Sr10Cu24O41 as a starting point for investigating doped ladders and their tendency toward superconductivity. A key feature was the separation of one-triplon and two-triplon scattering. Two-triplon scattering is observed quantitatively for the first time and so access is realized to the important strong magnetic quantum fluctuations. The spin gap is found to be 26.4+/-0.3 meV. The data are successfully modeled using the continuous unitary transformation method, and the exchange constants are determined by fitting to be Jleg=186 meV and Jrung=124 meV along the leg and rung, respectively; a substantial cyclic exchange of Jcyc=31 meV is confirmed.
Collapse
Affiliation(s)
- S Notbohm
- Hahn-Meitner-Institut Berlin, Berlin, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Lisunov KG, Arushanov E, Raquet B, Broto JM, Chou FC, Wizent N, Behr G. Hopping conductivity in CaCu(2)O(3) single crystals. J Phys Condens Matter 2006; 18:8541-8549. [PMID: 21690907 DOI: 10.1088/0953-8984/18/37/012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The resistivity, ρ, of the spin-ladder compound CaCu(2)O(3) is investigated between T∼130-450 K. The ρ(T) data measured for [Formula: see text] (along the Cu-O-Cu leg) and [Formula: see text] (along the Cu-O-Cu rungs), ρ(a)(T)>ρ(b)(T), exhibit an activated dependence, similar in both directions and characterized by a nearest-neighbour hopping followed by a variable-range hopping (VRH) regime when T is decreased. A detailed analysis of ρ(T) demonstrates that conventional d-dimensional models of the hopping conductivity, based on the electron localization in disordered systems, cannot interpret the experimental data at any d = 1, 2 or 3, leading to the mismatch of the characteristic energies and/or unphysical values of the characteristic length scales. The observed VRH conductivity law on the low-temperature interval, lnρ∼T(-3/4), contradicts the models above, too. Instead, it is found that this law can be substantiated and the correct matching of the energy and length scales can be found within a model of Fogler et al (2004 Phys. Rev. B 69 035413) by treating CaCu(2)O(3) as a three-dimensional array of quasi-one-dimensional electron crystals.
Collapse
Affiliation(s)
- K G Lisunov
- Institute of Applied Physics, Academy of Sciences of Moldova, Academiei Street 5, MD-2028 Kishinev, Moldova
| | | | | | | | | | | | | |
Collapse
|
23
|
Pothos E, Behr G, Frank L, Stiles L. WITHDRAWN: Prewired synaptic plasticity in central dopamine systems of obesity-prone rats and mice. Appetite 2006. [DOI: 10.1016/j.appet.2006.03.206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
24
|
Leisegang T, Meyer DC, Souptel D, Behr G, Wosnitza J, Paufler P. Electron density analysis of borocarbides. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305082255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
25
|
Behr G, Löser W, Apostu MO, Gruner W, Hücker M, Schramm L, Souptel D, Teresiak A, Werner J. Floating zone growth of CuO under elevated oxygen pressure and its relevance for the crystal growth of cuprates. Cryst Res Technol 2004. [DOI: 10.1002/crat.200410303] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
26
|
Leisegang T, Meyer DC, Souptel D, Behr G, Paufler P. Fourier difference analysis of HoNi 2B 2C single crystals. Acta Crystallogr A 2004. [DOI: 10.1107/s0108767304096424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
27
|
Oswald S, Behr G, Dobler D, Werner J, Wetzig K, Arabczyk W. Specific properties of fine SnO 2 powders connected with surface segregation. Anal Bioanal Chem 2004; 378:411-5. [PMID: 14634703 DOI: 10.1007/s00216-003-2277-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2003] [Revised: 08/27/2003] [Accepted: 09/05/2003] [Indexed: 10/26/2022]
Abstract
The effect of surface segregation in Sb- and In-doped SnO2 fine-grained powders has been analyzed in comparison with single-crystalline samples. The kinetics and thermodynamics of the Sb and In segregation processes were studied as a function of annealing temperature by X-ray photoelectron spectroscopy (XPS) after annealing in an oxygen-containing atmosphere. Significant differences between diffusion and segregation were revealed for doped powders and single crystals, obviously because of simultaneous diffusion and particle-growth processes proceeding during annealing of powders. For doped single crystals the thermodynamic equilibrium is approached after 24 h annealing above 850 degrees C and at 1000 degrees C for Sb and In, respectively. Higher effective activation energies of diffusion are observed for doped powders and the thermodynamic equilibrium is not achieved under technologically relevant annealing conditions. On the basis of dopant profile measurements anomalies in the electrical resistivity at 300 degrees C of Sb-doped SnO2 powders annealed at 700 and 900 degrees C were attributed to an Sb-depleted zone formed beneath the segregated surface during the kinetic regime. To achieve optimum resistivity behavior for commercial application, inhomogeneous doping of powders must be avoided by appropriate preparation steps.
Collapse
Affiliation(s)
- S Oswald
- Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, Postfach 270116, 01171 Dresden, Germany.
| | | | | | | | | | | |
Collapse
|
28
|
|
29
|
Borowiak-Palen E, Pichler T, Fuentes GG, Bendjemil B, Liu X, Graff A, Behr G, Kalenczuk RJ, Knupfer M, Fink J. Infrared response of multiwalled boron nitride nanotubes. Chem Commun (Camb) 2003:82-3. [PMID: 12610976 DOI: 10.1039/b208214d] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the infrared (IR) response of bulk samples of multiwalled boron nitride nanotubes, produced by a substitution reaction from single walled carbon nanotubes, which is dominated by two characteristic BN-vibrations at 800 and 1372 cm-1.
Collapse
Affiliation(s)
- E Borowiak-Palen
- Leibniz Institute for Solid State and Material Research Dresden, D-01171 Dresden, Germany.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Dobler D, Oswald S, Werner J, Arabczyk W, Behr G, Wetzig K. X-ray photoelectron spectroscopy investigation of segregation processes at Sb and In doped SnO2. Chem Phys 2003. [DOI: 10.1016/s0301-0104(02)00970-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
31
|
Szczuko D, Werner J, Behr G, Oswald S, Wetzig K. Surface-related investigations to characterize different preparation techniques of Sb-doped SnO2 powders. SURF INTERFACE ANAL 2001. [DOI: 10.1002/sia.1099] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
32
|
Sulzer D, Bogulavsky J, Larsen KE, Behr G, Karatekin E, Kleinman MH, Turro N, Krantz D, Edwards RH, Greene LA, Zecca L. Neuromelanin biosynthesis is driven by excess cytosolic catecholamines not accumulated by synaptic vesicles. Proc Natl Acad Sci U S A 2000; 97:11869-74. [PMID: 11050221 PMCID: PMC17261 DOI: 10.1073/pnas.97.22.11869] [Citation(s) in RCA: 307] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Melanin, the pigment in hair, skin, eyes, and feathers, protects external tissue from damage by UV light. In contrast, neuromelanin (NM) is found in deep brain regions, specifically in loci that degenerate in Parkinson's disease. Although this distribution suggests a role for NM in Parkinson's disease neurodegeneration, the biosynthesis and function of NM have eluded characterization because of lack of an experimental system. We induced NM in rat substantia nigra and PC12 cell cultures by exposure to l-dihydroxyphenylalanine, which is rapidly converted to dopamine (DA) in the cytosol. This pigment was identical to human NM as assessed by paramagnetic resonance and was localized in double membrane autophagic vacuoles identical to NM granules of human substantia nigra. NM synthesis was abolished by adenoviral-mediated overexpression of the synaptic vesicle catecholamine transporter VMAT2, which decreases cytosolic DA by increasing vesicular accumulation of neurotransmitter. The NM is in a stable complex with ferric iron, and NM synthesis was inhibited by the iron chelator desferrioxamine, indicating that cytosolic DA and dihydroxyphenylalanine are oxidized by iron-mediated catalysis to membrane-impermeant quinones and semiquinones. NM synthesis thus results from excess cytosolic catecholamines not accumulated into synaptic vesicles. The permanent accumulation of excess catechols, quinones, and catechol adducts into a membrane-impermeant substance trapped in organelles may provide an antioxidant mechanism for catecholamine neurons. However, NM in organelles associated with secretory pathways may interfere with signaling, as it delays stimulated neurite outgrowth in PC12 cells.
Collapse
Affiliation(s)
- D Sulzer
- Department of Neurology, Columbia University, New York, NY 10032, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Behr G, Löser W, Graw G, Bitterlich H, Fink J, Schultz L. Crystal Growth of High-melting Multi-component Rare Earth-Transition Metal Intermetallic Compounds from the Melt. Cryst Res Technol 2000. [DOI: 10.1002/1521-4079(200004)35:4%3c461::aid-crat461%3e3.0.co;2-d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
34
|
Behr G, Löser W, Graw G, Bitterlich H, Fink J, Schultz L. Crystal Growth of High-melting Multi-component Rare Earth-Transition Metal Intermetallic Compounds from the Melt. Cryst Res Technol 2000. [DOI: 10.1002/1521-4079(200004)35:4<461::aid-crat461>3.0.co;2-d] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
35
|
|
36
|
|
37
|
Moore K, Behr G. Myths on the rocks: using and abusing alcohol (continuing education credit). Nurs Stand 1993; 8:3-8; quiz 11-3. [PMID: 8260423 DOI: 10.7748/ns.8.8.77.s69] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
|
38
|
Barron PM, Buch E, Behr G, Crisp NG. Mass immunisation campaigns--do they solve the problem? S Afr Med J 1987; 72:321-2. [PMID: 3616833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Mass immunisation campaigns have been successfully used for vaccine delivery in countries such as Brazil and Turkey as well as in a number of instances locally. Although in some circumstances mass campaigns have been advantageous, they are not recommended as a basic policy for South Africa. Immunisation services should be incorporated into routine primary health care delivery as part of maternal and child services. If these services are adequately delivered there would be no need for mass campaigns.
Collapse
|
39
|
Behr G, Bartsch K, Jurisch M, Schönherr M, Wolf E. Preparation of high purity V3Si single crystals using a silicothermic reaction. Cryst Res Technol 1985. [DOI: 10.1002/crat.2170200930] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
40
|
|
41
|
Behr G. Charles White of Manchester: the 250th anniversary of his birth. Br Med J 1978; 2:1699-700. [PMID: 367513 PMCID: PMC1608996 DOI: 10.1136/bmj.2.6153.1699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
42
|
Behr G. Joint consultative committees. West J Med 1978. [DOI: 10.1136/bmj.1.6127.1626-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
43
|
Abstract
A passive method for the disposal of waste anaesthetic gases is described. The resistance characteristics of the collector valve, the balancing device and the disposal system were studied. It was found that the resistances offered by the conduction channels and the terminal exhaust valve were extremely low. The collector valves were found to be responsible for most of the expiratory resistance. Swabs taken from various components of the system showed that these were contaminated mainly with commensals and non-pathogenic organisms.
Collapse
|
44
|
|
45
|
|
46
|
|
47
|
Abstract
Concentrations of both magnesium and potassium were significantly increased in normal heart muscle samples from an area with a soft water supply compared with matched samples from an area with hard water. The zinc contrentration was also slightly increased in the soft water area. The magnesium/potassium ratio was significantly lower in the softwater area. This relative deficiency of magnesium may increase the risk of death after myocardial infarction in soft-water areas.
Collapse
|
48
|
|
49
|
Abstract
The percentage nitroblue-tetrazolium (NBT) leucocyte levels were evaluated daily in the 10 days following a first attack of coronary thrombosis. In 12 uncomplicated cases the peak increase was on the second or third day; thereafter the level declined and was below 10% by the tenth day. Three other patients did not conform to this pattern of NBT behaviour. They had experienced a second myocardial infarction and this was attended by a secondary rise in the NBT score; in the two survivors the score remained elevated on the tenth day. Comparison of the score on the second-third and tenth-fourteenth days is a possible useful index of a further complication.
Collapse
|
50
|
Mehta S, Behr G, Kenyon D. The effect of volatile anaesthetics on common respiratory pathogens. Halothane, trichloroethylene and methoxyflurane. Anaesthesia 1974; 29:280-9. [PMID: 4600937 DOI: 10.1111/j.1365-2044.1974.tb00645.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|