1
|
Jiménez JL, Crone SPG, Fogh E, Zayed ME, Lortz R, Pomjakushina E, Conder K, Läuchli AM, Weber L, Wessel S, Honecker A, Normand B, Rüegg C, Corboz P, Rønnow HM, Mila F. A quantum magnetic analogue to the critical point of water. Nature 2021; 592:370-375. [PMID: 33854247 DOI: 10.1038/s41586-021-03411-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 02/26/2021] [Indexed: 02/02/2023]
Abstract
At the liquid-gas phase transition in water, the density has a discontinuity at atmospheric pressure; however, the line of these first-order transitions defined by increasing the applied pressure terminates at the critical point1, a concept ubiquitous in statistical thermodynamics2. In correlated quantum materials, it was predicted3 and then confirmed experimentally4,5 that a critical point terminates the line of Mott metal-insulator transitions, which are also first-order with a discontinuous charge carrier density. In quantum spin systems, continuous quantum phase transitions6 have been controlled by pressure7,8, applied magnetic field9,10 and disorder11, but discontinuous quantum phase transitions have received less attention. The geometrically frustrated quantum antiferromagnet SrCu2(BO3)2 constitutes a near-exact realization of the paradigmatic Shastry-Sutherland model12-14 and displays exotic phenomena including magnetization plateaus15, low-lying bound-state excitations16, anomalous thermodynamics17 and discontinuous quantum phase transitions18,19. Here we control both the pressure and the magnetic field applied to SrCu2(BO3)2 to provide evidence of critical-point physics in a pure spin system. We use high-precision specific-heat measurements to demonstrate that, as in water, the pressure-temperature phase diagram has a first-order transition line that separates phases with different local magnetic energy densities, and that terminates at an Ising critical point. We provide a quantitative explanation of our data using recently developed finite-temperature tensor-network methods17,20-22. These results further our understanding of first-order quantum phase transitions in quantum magnetism, with potential applications in materials where anisotropic spin interactions produce the topological properties23,24 that are useful for spintronic applications.
Collapse
Affiliation(s)
- J Larrea Jiménez
- Laboratory for Quantum Matter under Extreme Conditions, Institute of Physics, University of São Paulo, São Paulo, Brazil.,Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - S P G Crone
- Institute for Theoretical Physics, University of Amsterdam, Amsterdam, The Netherlands.,Delta Institute for Theoretical Physics, University of Amsterdam, Amsterdam, The Netherlands
| | - E Fogh
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - M E Zayed
- Department of Physics, Carnegie Mellon University in Qatar, Doha, Qatar
| | - R Lortz
- Department of Physics, Hong Kong University of Science and Technology, Kowloon, Hong Kong
| | - E Pomjakushina
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, Villigen-PSI, Switzerland
| | - K Conder
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, Villigen-PSI, Switzerland
| | - A M Läuchli
- Institut für Theoretische Physik, Universität Innsbruck, Innsbruck, Austria
| | - L Weber
- Institut für Theoretische Festkörperphysik, RWTH Aachen University, Aachen, Germany
| | - S Wessel
- Institut für Theoretische Festkörperphysik, RWTH Aachen University, Aachen, Germany
| | - A Honecker
- Laboratoire de Physique Théorique et Modélisation, CNRS UMR 8089, CY Cergy Paris Université, Cergy-Pontoise, France
| | - B Normand
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.,Paul Scherrer Institute, Villigen-PSI, Switzerland
| | - Ch Rüegg
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.,Paul Scherrer Institute, Villigen-PSI, Switzerland.,Institute for Quantum Electronics, ETH Zürich, Hönggerberg, Switzerland.,Department of Quantum Matter Physics, University of Geneva, Geneva, Switzerland
| | - P Corboz
- Institute for Theoretical Physics, University of Amsterdam, Amsterdam, The Netherlands.,Delta Institute for Theoretical Physics, University of Amsterdam, Amsterdam, The Netherlands
| | - H M Rønnow
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
| | - F Mila
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| |
Collapse
|
2
|
Svitlyk V, Garbarino G, Rosa AD, Pomjakushina E, Krzton-Maziopa A, Conder K, Nunez-Regueiro M, Mezouar M. High-pressure polymorphism of BaFe 2Se 3. J Phys Condens Matter 2019; 31:085401. [PMID: 30530951 DOI: 10.1088/1361-648x/aaf777] [Citation(s) in RCA: 1] [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: 06/09/2023]
Abstract
BaFe2Se3 is a potential superconductor material exhibiting transition at 11 K and ambient pressure. Here we extended the structural and performed electrical resistivity measurements on this compound up to 51 GPa and 20 GPa, respectively, in order to distinguish if the superconductivity in this sample is intrinsic to the BaFe2Se3 phase or if it is originating from minor FeSe impurities that show a similar superconductive transition temperature. The electrical resistance measurements as a function of pressure show that at 5 GPa the superconducting transition is observed at around 10 K, similar to the one previously observed for this sample at ambient pressure. This indicates that the superconductivity in this sample is most likely intrinsic to the BaFe2Se3 phase and not to FeSe with T c > 20 K at these pressures. Further increase in pressure suppressed the superconductive signal and the sample remained in an insulating state up to the maximum achieved pressure of 20 GPa. Single-crystal and powder x-ray diffraction measurements revealed two structural transformations in BaFe2Se3: a second order transition above 3.5 GPa from Pnma (CsAg2I3-type structure) to Cmcm (CsCu2Cl3-type structure) and a first order transformation at 16.6 GPa. Here, γ-BaFe2Se3 transforms into δ-BaFe2Se3 (Cmcm, CsCu2Cl3-type average structure) via a first order phase transition mechanism. This transition is characterized by a significant shortening of the b lattice parameter of γ-BaFe2Se3 (17%) and accompanied by an anisotropic expansion in the orthogonal ac plane at the transition point.
Collapse
Affiliation(s)
- V Svitlyk
- European Synchrotron Radiation Facility, 38000 Grenoble, France
| | | | | | | | | | | | | | | |
Collapse
|
3
|
Xu N, Wang ZW, Magrez A, Bugnon P, Berger H, Matt CE, Strocov VN, Plumb NC, Radovic M, Pomjakushina E, Conder K, Dil JH, Mesot J, Yu R, Ding H, Shi M. Evidence of a Coulomb-Interaction-Induced Lifshitz Transition and Robust Hybrid Weyl Semimetal in T_{d}-MoTe_{2}. Phys Rev Lett 2018; 121:136401. [PMID: 30312078 DOI: 10.1103/physrevlett.121.136401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/16/2018] [Indexed: 06/08/2023]
Abstract
Using soft x-ray angle-resolved photoemission spectroscopy we probed the bulk electronic structure of T_{d}-MoTe_{2}. We found that on-site Coulomb interaction leads to a Lifshitz transition, which is essential for a precise description of the electronic structure. A hybrid Weyl semimetal state with a pair of energy bands touching at both type-I and type-II Weyl nodes is indicated by comparing the experimental data with theoretical calculations. Unveiling the importance of Coulomb interaction opens up a new route to comprehend the unique properties of MoTe_{2}, and is significant for understanding the interplay between correlation effects, strong spin-orbit coupling and superconductivity in this van der Waals material.
Collapse
Affiliation(s)
- N Xu
- Institute of Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Z W Wang
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - A Magrez
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - P Bugnon
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - H Berger
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - C E Matt
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Radovic
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - E Pomjakushina
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - K Conder
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - J H Dil
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - J Mesot
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - R Yu
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - H Ding
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| |
Collapse
|
4
|
Guguchia Z, Roessli B, Khasanov R, Amato A, Pomjakushina E, Conder K, Uemura YJ, Tranquada JM, Keller H, Shengelaya A. Complementary Response of Static Spin-Stripe Order and Superconductivity to Nonmagnetic Impurities in Cuprates. Phys Rev Lett 2017; 119:087002. [PMID: 28952761 DOI: 10.1103/physrevlett.119.087002] [Citation(s) in RCA: 4] [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: 04/22/2017] [Indexed: 06/07/2023]
Abstract
We report muon-spin rotation and neutron-scattering experiments on nonmagnetic Zn impurity effects on the static spin-stripe order and superconductivity of the La214 cuprates. Remarkably, it was found that, for samples with hole doping x≈1/8, the spin-stripe ordering temperature T_{so} decreases linearly with Zn doping y and disappears at y≈4%, demonstrating a high sensitivity of static spin-stripe order to impurities within a CuO_{2} plane. Moreover, T_{so} is suppressed by Zn in the same manner as the superconducting transition temperature T_{c} for samples near optimal hole doping. This surprisingly similar sensitivity suggests that the spin-stripe order is dependent on intertwining with superconducting correlations.
Collapse
Affiliation(s)
- Z Guguchia
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - B Roessli
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - R Khasanov
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - A Amato
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - E Pomjakushina
- Laboratory for scientific developments and novel materials, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - K Conder
- Laboratory for scientific developments and novel materials, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - Y J Uemura
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - J M Tranquada
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - H Keller
- Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - A Shengelaya
- Department of Physics, Tbilisi State University, Chavchavadze 3, GE-0128 Tbilisi, Georgia
- Andronikashvili Institute of Physics, I. Javakhishvili Tbilisi State University, Tamarashvili Street 6, 0177 Tbilisi, Georgia
| |
Collapse
|
5
|
Xu N, Autès G, Matt CE, Lv BQ, Yao MY, Bisti F, Strocov VN, Gawryluk D, Pomjakushina E, Conder K, Plumb NC, Radovic M, Qian T, Yazyev OV, Mesot J, Ding H, Shi M. Distinct Evolutions of Weyl Fermion Quasiparticles and Fermi Arcs with Bulk Band Topology in Weyl Semimetals. Phys Rev Lett 2017; 118:106406. [PMID: 28339253 DOI: 10.1103/physrevlett.118.106406] [Citation(s) in RCA: 2] [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: 08/12/2016] [Indexed: 06/06/2023]
Abstract
The Weyl semimetal phase is a recently discovered topological quantum state of matter characterized by the presence of topologically protected degeneracies near the Fermi level. These degeneracies are the source of exotic phenomena, including the realization of chiral Weyl fermions as quasiparticles in the bulk and the formation of Fermi arc states on the surfaces. Here, we demonstrate that these two key signatures show distinct evolutions with the bulk band topology by performing angle-resolved photoemission spectroscopy, supported by first-principles calculations, on transition-metal monophosphides. While Weyl fermion quasiparticles exist only when the chemical potential is located between two saddle points of the Weyl cone features, the Fermi arc states extend in a larger energy scale and are robust across the bulk Lifshitz transitions associated with the recombination of two nontrivial Fermi surfaces enclosing one Weyl point into a single trivial Fermi surface enclosing two Weyl points of opposite chirality. Therefore, in some systems (e.g., NbP), topological Fermi arc states are preserved even if Weyl fermion quasiparticles are absent in the bulk. Our findings not only provide insight into the relationship between the exotic physical phenomena and the intrinsic bulk band topology in Weyl semimetals, but also resolve the apparent puzzle of the different magnetotransport properties observed in TaAs, TaP, and NbP, where the Fermi arc states are similar.
Collapse
Affiliation(s)
- N Xu
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - G Autès
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - C E Matt
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - B Q Lv
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - M Y Yao
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - F Bisti
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - D Gawryluk
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - E Pomjakushina
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - K Conder
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Radovic
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - T Qian
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - O V Yazyev
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - J Mesot
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - H Ding
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| |
Collapse
|
6
|
Krzton-Maziopa A, Svitlyk V, Pomjakushina E, Puzniak R, Conder K. Superconductivity in alkali metal intercalated iron selenides. J Phys Condens Matter 2016; 28:293002. [PMID: 27248118 DOI: 10.1088/0953-8984/28/29/293002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Alkali metal intercalated iron selenide superconductors A x Fe2-y Se2 (where A = K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations.
Collapse
Affiliation(s)
- A Krzton-Maziopa
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, PL-00-664 Warsaw, Poland
| | | | | | | | | |
Collapse
|
7
|
Plumb NC, Gawryluk DJ, Wang Y, Ristić Z, Park J, Lv BQ, Wang Z, Matt CE, Xu N, Shang T, Conder K, Mesot J, Johnston S, Shi M, Radović M. Momentum-Resolved Electronic Structure of the High-T_{c} Superconductor Parent Compound BaBiO_{3}. Phys Rev Lett 2016; 117:037002. [PMID: 27472130 DOI: 10.1103/physrevlett.117.037002] [Citation(s) in RCA: 9] [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: 03/03/2016] [Indexed: 05/12/2023]
Abstract
We investigate the band structure of BaBiO_{3}, an insulating parent compound of doped high-T_{c} superconductors, using in situ angle-resolved photoemission spectroscopy on thin films. The data compare favorably overall with density functional theory calculations within the local density approximation, demonstrating that electron correlations are weak. The bands exhibit Brillouin zone folding consistent with known BiO_{6} breathing distortions. Though the distortions are often thought to coincide with Bi^{3+}/Bi^{5+} charge ordering, core level spectra show that bismuth is monovalent. We further demonstrate that the bands closest to the Fermi level are primarily oxygen derived, while the bismuth 6s states mostly contribute to dispersive bands at deeper binding energy. The results support a model of Bi-O charge transfer in which hole pairs are localized on combinations of the O 2p orbitals.
Collapse
Affiliation(s)
- N C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - D J Gawryluk
- Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Y Wang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA
| | - Z Ristić
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - J Park
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - B Q Lv
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Z Wang
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Department of Quantum Matter Physics, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - C E Matt
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - N Xu
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - T Shang
- Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - K Conder
- Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - J Mesot
- Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - S Johnston
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Radović
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- SwissFEL, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| |
Collapse
|
8
|
Panfilov AS, Grechnev GE, Fedorchenko AV, Conder K, Pomjakushina EV. Magnetic properties of Mn-doped Bi2Se3 compound: temperature dependence and pressure effects. J Phys Condens Matter 2015; 27:456002. [PMID: 26471893 DOI: 10.1088/0953-8984/27/45/456002] [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: 06/05/2023]
Abstract
Magnetic susceptibility χ of Bi2-x Mn x Se3 (x = 0.01-0.2) was measured in the temperature range 4.2-300 K. For all the samples, a Curie-Weiss behaviour of χ(T) was revealed with effective magnetic moments of Mn ions corresponding to the spin value S = 5/2, which couple antiferromagnetically with the paramagnetic Curie temperature Θ ~ -50 K. In addition, for the samples of nominal composition x = 0.1 and 0.2 the effect of a hydrostatic pressure P up to 2 kbar on χ has been measured at fixed temperatures 78 and 300 K that allowed to estimate the pressure derivative of Θ to be dΘ/dP ~ -0.8 K kbar(-1). Based on the observed behaviour of Θ with varied Mn concentration and pressure, a possible mechanism of interaction between localized Mn moments is discussed.
Collapse
Affiliation(s)
- A S Panfilov
- B Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, 61103 Kharkov, Ukraine
| | | | | | | | | |
Collapse
|
9
|
Stender D, Frison R, Conder K, Rupp JLM, Scherrer B, Martynczuk JM, Gauckler LJ, Schneider CW, Lippert T, Wokaun A. Crystallization of zirconia based thin films. Phys Chem Chem Phys 2015; 17:18613-20. [PMID: 26119755 DOI: 10.1039/c5cp02631h] [Citation(s) in RCA: 5] [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] [Indexed: 11/21/2022]
Abstract
The crystallization kinetics of amorphous 3 and 8 mol% yttria stabilized zirconia (3YSZ and 8YSZ) thin films grown by pulsed laser deposition (PLD), spray pyrolysis and dc-magnetron sputtering are explored. The deposited films were heat treated up to 1000 °C ex situ and in situ in an X-ray diffractometer. A minimum temperature of 275 °C was determined at which as-deposited amorphous PLD grown 3YSZ films fully crystallize within five hours. Above 325 °C these films transform nearly instantaneously with a high degree of micro-strain when crystallized below 500 °C. In these films the t'' phase crystallizes which transforms at T > 600 °C to the t' phase upon relaxation of the micro-strain. Furthermore, the crystallization of 8YSZ thin films grown by PLD, spray pyrolysis and dc-sputtering are characterized by in situ XRD measurements. At a constant heating rate of 2.4 K min(-1) crystallization is accomplished after reaching 800 °C, while PLD grown thin films were completely crystallized already at ca. 300 °C.
Collapse
Affiliation(s)
- D Stender
- Paul Scherrer Institut, Research Department General Energy, 5232 Villigen, Switzerland.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Zayed ME, Rüegg C, Strässle T, Stuhr U, Roessli B, Ay M, Mesot J, Link P, Pomjakushina E, Stingaciu M, Conder K, Rønnow HM. Correlated decay of triplet excitations in the Shastry-Sutherland compound SrCu2(BO3)2. Phys Rev Lett 2014; 113:067201. [PMID: 25148346 DOI: 10.1103/physrevlett.113.067201] [Citation(s) in RCA: 4] [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: 04/15/2014] [Indexed: 06/03/2023]
Abstract
The temperature dependence of the gapped triplet excitations (triplons) in the 2D Shastry-Sutherland quantum magnet SrCu(2)(BO(3))(2) is studied by means of inelastic neutron scattering. The excitation amplitude rapidly decreases as a function of temperature, while the integrated spectral weight can be explained by an isolated dimer model up to 10 K. Analyzing this anomalous spectral line shape in terms of damped harmonic oscillators shows that the observed damping is due to a two-component process: one component remains sharp and resolution limited while the second broadens. We explain the underlying mechanism through a simple yet quantitatively accurate model of correlated decay of triplons: an excited triplon is long lived if no thermally populated triplons are nearby but decays quickly if there are. The phenomenon is a direct consequence of frustration induced triplon localization in the Shastry-Sutherland lattice.
Collapse
Affiliation(s)
- M E Zayed
- Department of Mathematics, Statistics and Physics, College of Arts and Science, Qatar University, P.O. Box 2713, Doha, Qatar and Laboratory for Quantum Magnetism, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland and Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Ch Rüegg
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland and DPMC-MaNEP, University of Geneva, CH-1211 Geneva, Switzerland and London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Th Strässle
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - U Stuhr
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - B Roessli
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - M Ay
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - J Mesot
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland and Laboratory for Neutron and Synchrotron Spectroscopy, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland and Laboratory for Solid State Physics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - P Link
- Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM-2), D-85747 Garching, Germany
| | - E Pomjakushina
- Laboratory for Developments and Methods, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - M Stingaciu
- Laboratory for Developments and Methods, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - K Conder
- Laboratory for Developments and Methods, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - H M Rønnow
- Laboratory for Quantum Magnetism, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| |
Collapse
|
11
|
Guguchia Z, Khasanov R, Bendele M, Pomjakushina E, Conder K, Shengelaya A, Keller H. Negative oxygen isotope effect on the static spin stripe order in superconducting La(2-x)Ba(x)CuO(4) (x=1/8) observed by muon-spin rotation. Phys Rev Lett 2014; 113:057002. [PMID: 25126931 DOI: 10.1103/physrevlett.113.057002] [Citation(s) in RCA: 4] [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: 03/13/2014] [Indexed: 06/03/2023]
Abstract
Large negative oxygen-isotope (^{16}O and ^{18}O) effects (OIEs) on the static spin-stripe-ordering temperature T_{so} and the magnetic volume fraction V_{m} were observed in La_{2-x}Ba_{x}CuO_{4}(x=1/8) by means of muon-spin-rotation experiments. The corresponding OIE exponents were found to be α_{T_{so}}=-0.57(6) and α_{V_{m}}=-0.71(9), which are sign reversed to α_{T_{c}}=0.46(6) measured for the superconducting transition temperature T_{c}. This indicates that the electron-lattice interaction is involved in the stripe formation and plays an important role in the competition between bulk superconductivity and static stripe order in the cuprates.
Collapse
Affiliation(s)
- Z Guguchia
- Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - R Khasanov
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - M Bendele
- Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - E Pomjakushina
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - K Conder
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - A Shengelaya
- Department of Physics, Tbilisi State University, Chavchavadze 3, GE-0128 Tbilisi, Georgia
| | - H Keller
- Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| |
Collapse
|
12
|
Xu N, Biswas PK, Dil JH, Dhaka RS, Landolt G, Muff S, Matt CE, Shi X, Plumb NC, Radović M, Pomjakushina E, Conder K, Amato A, Borisenko SV, Yu R, Weng HM, Fang Z, Dai X, Mesot J, Ding H, Shi M. Direct observation of the spin texture in SmB6 as evidence of the topological Kondo insulator. Nat Commun 2014; 5:4566. [PMID: 25074332 DOI: 10.1038/ncomms5566] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 07/01/2014] [Indexed: 11/09/2022] Open
Abstract
Topological Kondo insulators have been proposed as a new class of topological insulators in which non-trivial surface states reside in the bulk Kondo band gap at low temperature due to strong spin-orbit coupling. In contrast to other three-dimensional topological insulators, a topological Kondo insulator is truly bulk insulating. Furthermore, strong electron correlations are present in the system, which may interact with the novel topological phase. By applying spin- and angle-resolved photoemission spectroscopy, here we show that the surface states of SmB6 are spin polarized. The spin is locked to the crystal momentum, fulfilling time reversal and crystal symmetries. Our results provide strong evidence that SmB6 can host topological surface states in a bulk insulating gap stemming from the Kondo effect, which can serve as an ideal platform for investigating of the interplay between novel topological quantum states with emergent effects and competing orders induced by strongly correlated electrons.
Collapse
Affiliation(s)
- N Xu
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - P K Biswas
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - J H Dil
- 1] Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland [2] Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - R S Dhaka
- 1] Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland [2] Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - G Landolt
- 1] Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland [2] Physik-Institut, Universität Zürich, Winterthurerstrauss 190, CH-8057 Zürich, Switzerland
| | - S Muff
- 1] Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland [2] Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - C E Matt
- 1] Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland [2] Laboratory for Solid State Physics, ETH Zürich, CH-8093, Zürich, Switzerland
| | - X Shi
- 1] Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland [2] Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - M Radović
- 1] Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland [2] SwissFEL, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - E Pomjakushina
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - K Conder
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - A Amato
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - S V Borisenko
- Institute for Solid State Research, IFW Dresden, PO Box 270116, D-01171 Dresden, Germany
| | - R Yu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - H-M Weng
- 1] Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China [2] Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Z Fang
- 1] Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China [2] Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - X Dai
- 1] Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China [2] Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - J Mesot
- 1] Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland [2] Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland [3] Laboratory for Solid State Physics, ETH Zürich, CH-8093, Zürich, Switzerland
| | - H Ding
- 1] Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China [2] Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| |
Collapse
|
13
|
Krzton-Maziopa A, Guguchia Z, Pomjakushina E, Pomjakushin V, Khasanov R, Luetkens H, Biswas PK, Amato A, Keller H, Conder K. Superconductivity in a new layered bismuth oxyselenide: LaO(0.5)F(0.5)BiSe₂. J Phys Condens Matter 2014; 26:215702. [PMID: 24805837 DOI: 10.1088/0953-8984/26/21/215702] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report superconductivity at T(c) ≈ 2.6 K in a new layered bismuth oxyselenide LaO(0.5)F(0.5)BiSe2 with the ZrCuSiAs-type structure composed of alternating superconducting BiSe2 and blocking LaO layers. The superconducting properties of LaO(0.5)F(0.5)BiSe2 were investigated by means of dc magnetization, resistivity and muon-spin rotation experiments, revealing the appearance of bulk superconductivity with a rather large superconducting volume fraction of ≈ 70% at 1.8 K.
Collapse
Affiliation(s)
- A Krzton-Maziopa
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
| | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Bendele M, Marini C, Joseph B, Simonelli L, Dore P, Pascarelli S, Chikovani M, Pomjakushina E, Conder K, Saini NL, Postorino P. Dispersive x-ray absorption studies at the Fe K-edge on the iron chalcogenide superconductor FeSe under pressure. J Phys Condens Matter 2013; 25:425704. [PMID: 24084478 DOI: 10.1088/0953-8984/25/42/425704] [Citation(s) in RCA: 2] [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: 06/02/2023]
Abstract
The local structure and the electronic properties of FeSe under hydrostatic pressure were studied by means of dispersive x-ray absorption measurements at the Fe K-edge. The pressure dependence of the x-ray absorption near edge structure features seems to follow the behavior of the superconducting transition temperature Tc. The local structure, that has an important impact on the superconducting properties, appears to fall into two regimes: the pressure dependence of the Fe-Fe bond distance shows a clear change in the compressibility at p ∼ 5 GPa; in contrast, the Fe-Se bond distance decreases continuously with increasing pressure with a lower compressibility than the Fe-Fe bond. The results suggest that the pressure dependent changes in Tc of FeSe are closely related to the changes in local structure.
Collapse
Affiliation(s)
- M Bendele
- Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro 2, I-00185 Roma, Italy
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Svitlyk V, Chernyshov D, Pomjakushina E, Krzton-Maziopa A, Conder K, Pomjakushin V, Pöttgen R, Dmitriev V. Crystal structure of BaFe2Se3 as a function of temperature and pressure: phase transition phenomena and high-order expansion of Landau potential. J Phys Condens Matter 2013; 25:315403. [PMID: 23838324 DOI: 10.1088/0953-8984/25/31/315403] [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: 06/02/2023]
Abstract
BaFe2Se3 (Pnma, CsAg2I3-type structure), recently assumed to show superconductivity at ~11 K, exhibits a pressure-dependent structural transition to the CsCu2Cl3-type structure (Cmcm space group) around 60 kbar, as evidenced from pressure-dependent synchrotron powder diffraction data. Temperature-dependent synchrotron powder diffraction data indicate an evolution of the room-temperature BaFe2Se3 structure towards a high-symmetry CsCu2Cl3 form upon heating. Around 425 K BaFe2Se3 undergoes a reversible, first-order isostructural transition, which is supported by the differential scanning calorimetry data. The temperature-dependent structural changes occur in two stages, as determined by the alignment of the FeSe4 tetrahedra and corresponding adjustments of the positions of Ba atoms. On further heating, a second-order phase transformation into the Cmcm structure is observed at 660 K. A rather unusual combination of isostructural and second-order phase transformations is parameterized within phenomenological theory assuming high-order expansion of the Landau potential. A generic phase diagram mapping observed structures is proposed on the basis of the parameterization.
Collapse
Affiliation(s)
- V Svitlyk
- Institut für Anorganische und Analytische Chemie, WWU Münster, Münster, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Casola F, Shiroka T, Feiguin A, Wang S, Grbić MS, Horvatić M, Krämer S, Mukhopadhyay S, Conder K, Berthier C, Ott HR, Rønnow HM, Rüegg C, Mesot J. Field-induced quantum soliton lattice in a frustrated two-leg spin-1/2 ladder. Phys Rev Lett 2013; 110:187201. [PMID: 23683239 DOI: 10.1103/physrevlett.110.187201] [Citation(s) in RCA: 3] [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: 11/27/2012] [Indexed: 06/02/2023]
Abstract
Based on high-field (31)P nuclear magnetic resonance experiments and accompanying numerical calculations, it is argued that in the frustrated S=1/2 ladder compound BiCu(2)PO(6) a field-induced soliton lattice develops above a critical field of μ(0)H(c1)=20.96(7) T. Solitons result from the fractionalization of the S=1, bosonlike triplet excitations, which in other quantum antiferromagnets are commonly known to experience Bose-Einstein condensation or to crystallize in a superstructure. Unlike in spin-Peierls systems, these field-induced quantum domain walls do not arise from a state with broken translational symmetry and are triggered exclusively by magnetic frustration. Our model predicts yet another second-order phase transition at H(c2)>H(c1), driven by soliton-soliton interactions, most likely corresponding to the one observed in recent magnetocaloric and other bulk measurements.
Collapse
Affiliation(s)
- F Casola
- Laboratorium für Festkörperphysik, ETH Hönggerberg, CH-8093 Zürich, Switzerland.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Biswas PK, Krzton-Maziopa A, Khasanov R, Luetkens H, Pomjakushina E, Conder K, Amato A. Two-dimensional superfluid density in an alkali metal-organic solvent intercalated iron selenide superconductor Li(C5H5N)0.2Fe2Se2. Phys Rev Lett 2013; 110:137003. [PMID: 23581361 DOI: 10.1103/physrevlett.110.137003] [Citation(s) in RCA: 4] [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: 09/21/2012] [Revised: 12/30/2012] [Indexed: 06/02/2023]
Abstract
We report the low-temperature electronic and magnetic properties of the alkali metal-organic solvent intercalated iron selenide superconductor Li(C5H5N)0.2Fe2Se2 using muon-spin-spectroscopy measurements. The zero-field muon spin relaxation (μSR) results indicate that nearly half of the sample is magnetically ordered and spatially phase separated from the superconducting region. The transverse-field μSR results reveal that the superfluid density of Li(C5H5N)0.2Fe2Se2 is two dimensional in nature. The temperature dependence of the penetration depth λ(T) can be explained using a two-gap s-wave model. This implies that, despite the 2D nature of the superfluid density, the symmetry of the superconducting gap remains unaltered to the parent compound FeSe.
Collapse
Affiliation(s)
- P K Biswas
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.
| | | | | | | | | | | | | |
Collapse
|
18
|
Yu Pomjakushin V, Krzton-Maziopa A, Pomjakushina EV, Conder K, Chernyshov D, Svitlyk V, Bosak A. Intrinsic crystal phase separation in the antiferromagnetic superconductor Rb(y)Fe(2-x)Se2: a diffraction study. J Phys Condens Matter 2012; 24:435701. [PMID: 23032696 DOI: 10.1088/0953-8984/24/43/435701] [Citation(s) in RCA: 3] [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] [Indexed: 06/01/2023]
Abstract
The crystal and magnetic structures of the superconducting iron-based chalcogenides Rb(y)Fe(2-x)Se(2) have been studied by means of single-crystal synchrotron x-ray and high-resolution neutron powder diffraction in the temperature range 2-570 K. The ground state of the crystal is an intrinsically phase-separated state with two distinct-by-symmetry phases. The main phase has the iron vacancy ordered √5 × √5 superstructure (I4/m space group) with AFM ordered Fe spins. The minority phase does not have √5 × √5-type of ordering and has a smaller in-plane lattice constant a and larger tetragonal c-axis and can be well described by assuming the parent average vacancy disordered structure (I4/mmm space group) with the refined stoichiometry Rb(0.60(5))(Fe(1.10(5))Se)(2). The minority phase amounts to 8-10% mass fraction. The unit cell volume of the minority phase is 3.2% smaller than the one of the main phase at T = 2 K and has quite different temperature dependence. The minority phase merges with the main vacancy ordered phase on heating above the phase separation temperature T(P) = 475 K. The spatial dimensions of the phase domains strongly increase above T(P) from 1000 to >2500 Å due to the integration of the regions of the main phase that were separated by the second phase at low temperatures. Additional annealing of the crystals at a temperature T = 488 K, close to T(P), for a long time drastically reduces the amount of the minority phase.
Collapse
Affiliation(s)
- V Yu Pomjakushin
- Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
| | | | | | | | | | | | | |
Collapse
|
19
|
Krzton-Maziopa A, Pomjakushina EV, Pomjakushin VY, von Rohr F, Schilling A, Conder K. Synthesis of a new alkali metal-organic solvent intercalated iron selenide superconductor with Tc ≈ 45 K. J Phys Condens Matter 2012; 24:382202. [PMID: 22945447 DOI: 10.1088/0953-8984/24/38/382202] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We report on a new iron selenide superconductor with a T(c) onset of 45 K and the nominal composition Li(x)(C(5)H(5)N)(y)Fe(2-z)Se(2), synthesized via intercalation of dissolved alkaline metal in anhydrous pyridine at room temperature. This superconductor exhibits a broad transition, reaching zero resistance at 10 K. Magnetization measurements reveal a superconducting shielding fraction of approximately 30%. Analogous phases intercalated with Na, K and Rb were also synthesized and characterized. The superconducting transition temperature of Li(x)(C(5)H(5)N)(y)Fe(2-z)Se(2) is clearly enhanced in comparison to those of the known superconductors FeSe(0.98) (T(c) ~ 8 K) and A(x)Fe(2-y)Se(2) (T(c) ~ 27-32 K) and is in close agreement with critical temperatures recently reported for Li(x)(NH(3))(y)Fe(2-z)Se(2). Post-annealing of intercalated material (Li(x)(C(5)H(5)N)(y)Fe(2-z)Se(2)) at elevated temperatures drastically enlarges the c-parameter of the unit cell (~44%) and increases the superconducting shielding fraction to nearly 100%. Our findings indicate a new synthesis route leading to possibly even higher critical temperatures for materials in this class: by intercalation of organic compounds between Fe-Se layers.
Collapse
Affiliation(s)
- A Krzton-Maziopa
- Laboratory for Developments and Methods, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
| | | | | | | | | | | |
Collapse
|
20
|
Bosak A, Svitlyk V, Popov A, de Sanctis D, Pomjakushina E, Pomjakushin V, Krzton-Maziopa A, Conder K, Chernyshov D. Three-dimensional mapping of reciprocal space and structural complexity of AxFe 2−ySe 2superconductors ( A= Rb, Cs). Acta Crystallogr A 2012. [DOI: 10.1107/s0108767312096389] [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
|
Schefer J, Ceretti M, Le Dreau L, Sura R, Prestipino C, Paulus W, Keller L, Conder K, Pomjakushina E, Pederson B. Oxygen diffusion and structural and properties in La 2−xSr xCuO 4+dand La 2CoO 4+d. Acta Crystallogr A 2012. [DOI: 10.1107/s0108767312095268] [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
|
22
|
Krzton-Maziopa A, Pomjakushina E, Pomjakushin V, Sheptyakov D, Chernyshov D, Svitlyk V, Conder K. The synthesis, and crystal and magnetic structure of the iron selenide BaFe2Se3 with possible superconductivity at Tc = 11 K. J Phys Condens Matter 2011; 23:402201. [PMID: 21931190 DOI: 10.1088/0953-8984/23/40/402201] [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] [Indexed: 05/31/2023]
Abstract
We report on the synthesis of single crystals of BaFe(2)Se(3) and study their crystal and magnetic structures by means of synchrotron single-crystal x-ray and neutron powder diffraction. The crystal structure has orthorhombic symmetry and consists of double chains of FeSe(4) edge connected tetrahedra intercalated with barium. Below 240 K, long range spin-block checkerboard antiferromagnetic order is developed. The magnetic structure is similar to one observed in A(0.8)Fe(1.6)Se(2) (A = K, Rb or Cs) superconductors. The crystals exhibit a transition to the diamagnetic state with an onset transition temperature of T(c) ∼ 11 K. Though we observe FeSe as an impurity phase (<0.8% mass fraction) it is not likely that the diamagnetism is attributable to the FeSe superconductor, which has T(c) ≈ 8.5 K.
Collapse
Affiliation(s)
- A Krzton-Maziopa
- Laboratory for Development and Methods, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | | | | | | | | | | | | |
Collapse
|
23
|
Svitlyk V, Chernyshov D, Pomjakushina E, Krzton-Maziopa A, Conder K, Pomjakushin V, Dmitriev V. Temperature and pressure evolution of the crystal structure of A(x)(Fe(1-y)Se)2 (A = Cs, Rb, K) studied by synchrotron powder diffraction. Inorg Chem 2011; 50:10703-8. [PMID: 21988233 DOI: 10.1021/ic201160y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Temperature-dependent synchrotron powder diffraction on Cs(0.83)(Fe(0.86)Se)(2) revealed first-order I4/m to I4/mmm structural transformation around 216 °C associated with a disorder of the Fe vacancies. Irreversibility observed during the transition is likely associated with a mobility of the intercalated alkali atoms. Pressure-dependent synchrotron powder diffraction on Cs(0.83)(Fe(1-y)Se)(2), Rb(0.85)(Fe(1-y)Se)(2), and K(0.8)(Fe(1-y)Se)(2) (y ~ 0.14) indicated that the I4/m superstructure reflections are present up to pressures of 120 kbar. This may indicate that the ordering of the Fe vacancies is present in both superconducting and nonsuperconductive states.
Collapse
Affiliation(s)
- V Svitlyk
- Swiss-Norwegian Beamlines at European Synchrotron Radiation Facility, BP 220, 38043 Grenoble, France.
| | | | | | | | | | | | | |
Collapse
|
24
|
Pomjakushina E, Krzton-Maziopa A, Conder K, Pomjakushin V. FeSe-based superconductors (11, 122-type): phase diagram, crystal growth and characterization. Acta Crystallogr A 2011. [DOI: 10.1107/s0108767311088532] [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: 11/11/2022] Open
|
25
|
Pomjakushin VY, Sheptyakov DV, Pomjakushina EV, Krzton-Maziopa A, Conder K, Chernyshov D, Svitlyk V, Shermadini Z. Iron vacancy superstructure and room-temperature antiferromagnetic order in superconducting XyFe 2−xSe 2( X= K, Cs, Rb). Acta Crystallogr A 2011. [DOI: 10.1107/s0108767311094815] [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
|
26
|
Svitlyk V, Chernyshov D, Pomjakushina E, Krzton-Maziopa A, Conder K, Pomjakushin V, Dmitriev V. Temperature and pressure evolution of the crystal structure of Ax(Fe 1−ySe) 2( A= Cs, Rb, K) studied by synchrotron X-ray diffraction. Acta Crystallogr A 2011. [DOI: 10.1107/s0108767311094025] [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
|
Pomjakushin VY, Pomjakushina EV, Krzton-Maziopa A, Conder K, Shermadini Z. Room temperature antiferromagnetic order in superconducting X(y)Fe(2-x)Se₂ (X = Rb, K): a neutron powder diffraction study. J Phys Condens Matter 2011; 23:156003. [PMID: 21460426 DOI: 10.1088/0953-8984/23/15/156003] [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
Magnetic and crystal structures of superconducting X(y)Fe(2-x)Se₂ (X = Rb and K with T(c) = 31.5 and 29.5 K) have been studied by neutron powder diffraction at room temperature. Both crystals show an ordered iron vacancy pattern and the crystal structure is well described by the I4/m space group with the lattice constants a = 8.799, c = 14.576 and a = 8.730, c = 14.115 Å and the refined stoichiometry x = 0.30(1), y = 0.83(2) and x = 0.34(1), y = 0.83(1) for Rb and K crystals, respectively. The structure contains one fully occupied iron position and one almost empty vacancy position. Assuming that the iron moment is ordered only on the fully occupied site we have sorted out all eight irreducible representations (irreps) for the propagation vector k = 0 and have found that irreps τ₂ and τ₇ fit the experimental data well with the moments along the c axis. The moment amplitudes amounted to 2.15(3) µ(B), 2.55(3) μ(B) for τ₂ and 2.08(6) μ(B), 2.57(3) μ(B) for τ₇ for Rb and K crystals, respectively. Irrep τ₂ corresponds to the Shubnikov group I4/m' and gives a constant moment antiferromagnetic configuration, whereas τ₇ does not have a Shubnikov counterpart and allows two different magnetic moments in the structure.
Collapse
Affiliation(s)
- V Yu Pomjakushin
- Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
| | | | | | | | | |
Collapse
|
28
|
Shermadini Z, Krzton-Maziopa A, Bendele M, Khasanov R, Luetkens H, Conder K, Pomjakushina E, Weyeneth S, Pomjakushin V, Bossen O, Amato A. Coexistence of magnetism and superconductivity in the iron-based compound Cs0.8(FeSe0.98)2. Phys Rev Lett 2011; 106:117602. [PMID: 21469895 DOI: 10.1103/physrevlett.106.117602] [Citation(s) in RCA: 15] [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: 01/10/2011] [Indexed: 05/30/2023]
Abstract
We report on muon-spin rotation and relaxation (μSR), electrical resistivity, magnetization and differential scanning calorimetry measurements performed on a high-quality single crystal of Cs(0.8)(FeSe(0.98))(2). Whereas our transport and magnetization data confirm the bulk character of the superconducting state below T(c)=29.6(2) K, the μSR data indicate that the system is magnetic below T(N)=478.5(3) K, where a first-order transition occurs. The first-order character of the magnetic transition is confirmed by differential scanning calorimetry data. Taken all together, these data indicate in Cs(0.8)(FeSe(0.98))(2) a microscopic coexistence between the superconducting phase and a strong magnetic phase. The observed T(N) is the highest reported to date for a magnetic superconductor.
Collapse
Affiliation(s)
- Z Shermadini
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Krzton-Maziopa A, Shermadini Z, Pomjakushina E, Pomjakushin V, Bendele M, Amato A, Khasanov R, Luetkens H, Conder K. Synthesis and crystal growth of Cs(0.8)(FeSe(0.98))(2): a new iron-based superconductor with T(c) = 27 K. J Phys Condens Matter 2011; 23:052203. [PMID: 21406902 DOI: 10.1088/0953-8984/23/5/052203] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We report on the synthesis of large single crystals of a new FeSe layer superconductor Cs(0.8)(FeSe(0.98))(2). X-ray powder diffraction, neutron powder diffraction and magnetization measurements have been used to compare the crystal structure and the magnetic properties of Cs(0.8)(FeSe(0.98))(2) with those of the recently discovered potassium intercalated system K(x)Fe(2)Se(2). The new compound, Cs(0.8)(FeSe(0.98))(2), shows a slightly lower superconducting transition temperature (T(c) = 27.4 K) in comparison to 29.5 in (K(0.8)(FeSe(0.98))(2)). The volume of the crystal unit cell increases by replacing K by Cs-the c parameter grows from 14.1353(13) to 15.2846(11) Å. For the alkali metal intercalated layered compounds known so far, (K(0.8)Fe(2)Se(2) and Cs(0.8)(FeSe(0.98))(2)), the T(c) dependence on the anion height (distance between Fe layers and Se layers) was found to be analogous to those reported for As-containing Fe superconductors and Fe(Se(1 - x)Ch(x)), where Ch = Te, S.
Collapse
Affiliation(s)
- A Krzton-Maziopa
- Laboratory for Developments and Methods, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Casola F, Shiroka T, Wang S, Conder K, Pomjakushina E, Mesot J, Ott HR. Direct observation of impurity-induced magnetism in a spin-(1/2) antiferromagnetic Heisenberg two-leg spin ladder. Phys Rev Lett 2010; 105:067203. [PMID: 20868003 DOI: 10.1103/physrevlett.105.067203] [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] [Received: 03/05/2010] [Revised: 06/01/2010] [Indexed: 05/29/2023]
Abstract
Nuclear magnetic resonance and magnetization measurements were used to probe the magnetic features of single-crystalline Bi(Cu(1-x)Zn(x))(2)PO(6) with 0<x<0.05 at temperatures between 2.6 K and 300 K. The simple line shape of the (31)P NMR signals of the pristine compound changes considerably for x>0 and we present clear evidence for a temperature-dependent variation of the local magnetization close to the Zn sites. The generic nature of this observation is indicated by results of model calculations on appropriate spin systems of limited size employing quantum Monte Carlo methods.
Collapse
Affiliation(s)
- F Casola
- Laboratorium für Festkörperphysik, ETH Hönggerberg, CH-8093 Zürich, Switzerland
| | | | | | | | | | | | | |
Collapse
|
31
|
Balédent V, Fauqué B, Sidis Y, Christensen NB, Pailhès S, Conder K, Pomjakushina E, Mesot J, Bourges P. Two-dimensional orbital-like magnetic order in the high-temperature La(2-x)Sr(x)CuO4 superconductor. Phys Rev Lett 2010; 105:027004. [PMID: 20867731 DOI: 10.1103/physrevlett.105.027004] [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: 03/19/2010] [Indexed: 05/29/2023]
Abstract
In high-temperature copper oxide superconductors, a novel magnetic order associated with the pseudogap phase has been identified in two different cuprate families over a wide region of temperature and doping. We report here the observation below 120 K of a similar magnetic ordering in the archetypal cuprate La(2-x)Sr(x)CuO4 (LSCO) system for x=0.085. In contrast with the previous reports, the magnetic ordering in LSCO is only short range with an in-plane correlation length of ∼10 A and is bidimensional (2D). Such a less pronounced order suggests an interaction with other electronic instabilities. In particular, LSCO also exhibits a strong tendency towards stripes ordering at the expense of the superconducting state.
Collapse
Affiliation(s)
- V Balédent
- Laboratoire Léon Brillouin, CEA-CNRS, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
| | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Babkevich P, Bendele M, Boothroyd AT, Conder K, Gvasaliya SN, Khasanov R, Pomjakushina E, Roessli B. Magnetic excitations of Fe(1+y)Se(x)Te(1-x) in magnetic and superconductive phases. J Phys Condens Matter 2010; 22:142202. [PMID: 21389522 DOI: 10.1088/0953-8984/22/14/142202] [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
We have used inelastic neutron scattering and muon-spin rotation to compare the low energy magnetic excitations in single crystals of superconducting Fe(1.01)Se(0.50)Te(0.50) and non-superconducting Fe(1.10)Se(0.25)Te(0.75). We confirm the existence of a spin resonance in the superconducting phase of Fe(1.01)Se(0.50)Te(0.50), at an energy of 7 meV and a wavevector of (1/2, 1/2, 0). The non-superconducting sample exhibits two incommensurate magnetic excitations at (1/2, 1/2, 0) ± (0.18, - 0.18, 0) which rise steeply in energy, but no resonance is observed at low energies. A strongly dispersive low energy magnetic excitation is also observed in Fe(1.10)Se(0.25)Te(0.75) close to the commensurate antiferromagnetic ordering wavevector (1/2 - δ, 0, 1/2), where δ≈0.03. The magnetic correlations in both samples are found to be quasi-two-dimensional in character and persist well above the magnetic (Fe(1.10)Se(0.25)Te(0.75)) and superconducting (Fe(1.01)Se(0.50)Te(0.50)) transition temperatures.
Collapse
Affiliation(s)
- P Babkevich
- Department of Physics, Clarendon Laboratory, Oxford University, Oxford OX1 3PU, UK.
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Pomjakushin VY, Sheptyakov DV, Pomjakushina EV, Conder K, Balagurov AM. Evidence for the strong effect of quenched correlated disorder on phase separation and magnetism in (La(1-y)Pr(y))0.7Ca0.3MnO3. J Phys Condens Matter 2010; 22:115601. [PMID: 21389468 DOI: 10.1088/0953-8984/22/11/115601] [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: 05/30/2023]
Abstract
High resolution neutron diffraction shows that the mesoscopic separation into ferromagnetic (FM) and antiferromagnetic (AFM) phases and the FM transition temperature T(C) in the perovskite manganite (La(1-y)Pr(y))(0.7)Ca(0.3)MnO(3) strongly depend on the quenched correlated disorder. The different disorder strengths are achieved by different procedures of the sample synthesis and are quantitatively characterized by the microstrain-type diffraction peak broadening. The system shifts to predominantly a one-phase state with smaller T(C) as the correlated disorder strength is decreased, supporting the viewpoint that the origin of phase separation in the indicated manganite system is the correlated quenched disorder. The ground state of an ultimately chemically homogeneous sample is FM-like containing about 20% of the AFM minority phase. This FM-like state can be readily transformed to the AFM-like one having < 20% of the FM phase by the decrease of the effective charge carrier bandwidth via oxygen isotope substitution.
Collapse
Affiliation(s)
- V Yu Pomjakushin
- Laboratory for Neutron Scattering, ETH Zurich and Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
| | | | | | | | | |
Collapse
|
34
|
Khasanov R, Bendele M, Amato A, Conder K, Keller H, Klauss HH, Luetkens H, Pomjakushina E. Evolution of two-gap behavior of the superconductor FeSe1-x. Phys Rev Lett 2010; 104:087004. [PMID: 20366961 DOI: 10.1103/physrevlett.104.087004] [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: 12/02/2009] [Indexed: 05/15/2023]
Abstract
The superfluid density, rho{s}, of the iron chalcogenide superconductor, FeSe1-x, was studied as a function of pressure by means of muon-spin rotation. The analysis of rho{s}(T) within the two-gap scheme reveals that the effect on both, the transition temperature T{c} and rho{s}(0), is entirely determined by the band(s) where the large superconducting gap develops, while the band(s) with the small gap become practically unaffected.
Collapse
Affiliation(s)
- R Khasanov
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Bendele M, Amato A, Conder K, Elender M, Keller H, Klauss HH, Luetkens H, Pomjakushina E, Raselli A, Khasanov R. Pressure induced static magnetic order in superconducting FeSe1-x. Phys Rev Lett 2010; 104:087003. [PMID: 20366960 DOI: 10.1103/physrevlett.104.087003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Indexed: 05/29/2023]
Abstract
We report on a detailed investigation of the electronic phase diagram of FeSe1-x under pressures up to 1.4 GPa by means of ac magnetization and muon-spin rotation. At a pressure approximately 0.8 GPa the nonmagnetic and superconducting FeSe1-x enters a region where static magnetic order is realized above T{c} and bulk superconductivity coexists and competes on short length scales with the magnetic order below T{c}. For even higher pressures an enhancement of both the magnetic and the superconducting transition temperatures as well as of the corresponding order parameters is observed. These exceptional properties make FeSe1-x to be one of the most interesting superconducting systems investigated extensively at present.
Collapse
Affiliation(s)
- M Bendele
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Le Dréau L, Paulus W, Schefer J, Conder K. Understanding the oxygen diffusion process in Ruddlesden-Popper phases at room temperature: the special case of La 2CoO 4+δ. Acta Crystallogr A 2009. [DOI: 10.1107/s0108767309094112] [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
|
37
|
Mulders AM, Lawrence SM, Staub U, Garcia-Fernandez M, Scagnoli V, Mazzoli C, Pomjakushina E, Conder K, Wang Y. Direct observation of charge order and an orbital glass state in multiferroic LuFe2O4. Phys Rev Lett 2009; 103:077602. [PMID: 19792687 DOI: 10.1103/physrevlett.103.077602] [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] [Received: 12/15/2008] [Indexed: 05/28/2023]
Abstract
Geometrical frustration of the Fe ions in LuFe2O4 leads to intricate charge and magnetic order and a strong magnetoelectric coupling. Using resonant x-ray diffraction at the Fe K edge, the anomalous scattering factors of both Fe sites are deduced from the (h/3 k/3 l/2) reflections. The chemical shift between the two types of Fe ions equals 4.0(1) eV corresponding to full charge separation into Fe2+ and Fe3+. The polarization and azimuthal angle dependence of the superlattice reflections demonstrate the absence of differences in anisotropic scattering revealing random orientations of the Fe2+ orbitals characteristic of an orbital glass state.
Collapse
Affiliation(s)
- A M Mulders
- Department of Imaging and Applied Physics, Curtin University of Technology, Perth, WA 6845, Australia
| | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Di Castro D, Khasanov R, Shengelaya A, Conder K, Jang DJ, Park MS, Lee SI, Keller H. Comparative study of the pressure effects on the magnetic penetration depth in electron- and hole-doped cuprate superconductors. J Phys Condens Matter 2009; 21:275701. [PMID: 21828498 DOI: 10.1088/0953-8984/21/27/275701] [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
The effect of pressure on the magnetic penetration depth λ was tested for the hole-doped superconductor YBa(2)Cu(3)O(7-δ) and in the electron-doped one Sr(0.9)La(0.1)CuO(2) by means of magnetization measurements. Whereas a large change of λ was found in YBa(2)Cu(3)O(7-δ), confirming the non-adiabatic character of the electron-phonon coupling in hole-doped superconductors, the same quantity is not affected by pressure in electron-doped Sr(0.9)La(0.1)CuO(2), suggesting a close similarity of the latter to conventional adiabatic Bardeen-Cooper-Schrieffer superconductors. The present results imply a remarkable difference between the electronic properties of hole-doped cuprates and electron-doped Sr(0.9)La(0.1)CuO(2), giving a strong contribution to the long debated asymmetric consequences of hole and electron doping in cuprate superconductors.
Collapse
Affiliation(s)
- D Di Castro
- CNR-INFM-Coherentia and Dipartimento di Ingegneria Meccanica, Universita' di Roma 'Tor Vergata', Via del Politecnico 1, I-00133 Roma, Italy
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Rasch JC, Sheptyakov D, Schefer J, Keller L, Boehm M, Gozzo F, Volkov N, Sablina K, Petrakovskii G, Grimmer H, Conder K, Löffler J. Structural properties of determined from high-resolution synchrotron powder diffraction. J SOLID STATE CHEM 2009. [DOI: 10.1016/j.jssc.2009.02.001] [Citation(s) in RCA: 11] [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: 10/21/2022]
|
40
|
Podlesnyak A, Russina M, Furrer A, Alfonsov A, Vavilova E, Kataev V, Büchner B, Strässle T, Pomjakushina E, Conder K, Khomskii DI. Spin-state polarons in lightly-hole-doped LaCoO3. Phys Rev Lett 2008; 101:247603. [PMID: 19113665 DOI: 10.1103/physrevlett.101.247603] [Citation(s) in RCA: 5] [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: 04/18/2008] [Indexed: 05/27/2023]
Abstract
Inelastic neutron scattering (INS), electron spin resonance (ESR), and nuclear magnetic resonance (NMR) measurements were employed to establish the origin of the strong magnetic signal in lightly-hole-doped La1-xSrxCoO3, x approximately 0.002. Both INS and ESR low temperature spectra show intense excitations with large effective g factors approximately 10-18. NMR data indicate the creation of extended magnetic clusters. From the Q dependence of the INS magnetic intensity, we conclude that the observed anomalies are caused by the formation of octahedrally shaped spin-state polarons comprising seven Co ions. The present INS, ESR, and NMR data give evidence for two regimes in the lightly-hole-doped samples: (i) T<35 K dominated by spin polarons; (ii) T>35 K dominated by thermally activated magnetic Co3+ ions.
Collapse
Affiliation(s)
- A Podlesnyak
- Hahn-Meitner-Institut, Glienicker Strasse 100, Berlin 14109, Germany.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Pomjakushin V, Furrer A, Pomjakushina E, Sheptyakov D, Conder K. Crystal and magnetic structure of quantum spin-trimer compounds Ca 3Cu 3−xNi x(PO 4) 4. Acta Crystallogr A 2008. [DOI: 10.1107/s0108767308084857] [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
|
42
|
Pomjakushina E, Conder K, Stingaciu M, Podlesnyak A. Layered and cubic cobaltites grown by floating zone, structural and magnetic properties study. Acta Crystallogr A 2008. [DOI: 10.1107/s0108767308098954] [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: 11/11/2022] Open
|
43
|
Khasanov R, Shengelaya A, Di Castro D, Morenzoni E, Maisuradze A, Savić IM, Conder K, Pomjakushina E, Bussmann-Holder A, Keller H. Oxygen isotope effects on the superconducting transition and magnetic states within the phase diagram of Y1-xPrxBa2Cu3O7-delta. Phys Rev Lett 2008; 101:077001. [PMID: 18764566 DOI: 10.1103/physrevlett.101.077001] [Citation(s) in RCA: 5] [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: 11/14/2007] [Indexed: 05/26/2023]
Abstract
The various phases observed in all cuprate superconductors [superconducting (SC), spin-glass (SG), and antiferromagnetic (AFM)] were investigated with respect to oxygen-isotope (16O/18O) effects, using here as a prototype system of cuprates Y1-xPrxBa2Cu3O7-delta. All phases exhibit an isotope effect which is strongest where the respective phase terminates. In addition, the isotope effects on the magnetic phases (SG and AFM) are sign reversed as compared to the one on the superconducting phase. In the coexistence regime of the SG and SC phase a two-component behavior is observed where the isotope induced decrease of the superfluid density leads to a corresponding enhancement in the SG related density.
Collapse
Affiliation(s)
- R Khasanov
- Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Luetkens H, Stingaciu M, Pashkevich YG, Conder K, Pomjakushina E, Gusev AA, Lamonova KV, Lemmens P, Klauss HH. Microscopic evidence of spin state order and spin state phase separation in layered cobaltites RBaCo2O5.5 with R=Y, Tb, Dy, and Ho. Phys Rev Lett 2008; 101:017601. [PMID: 18764150 DOI: 10.1103/physrevlett.101.017601] [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] [Received: 01/09/2008] [Indexed: 05/26/2023]
Abstract
We report muon-spin relaxation measurements on the magnetic structures of RBaCo2O(5.5) with R=Y, Tb, Dy, and Ho. Three different phases, one ferrimagnetic and two antiferromagnetic, are identified below 300 K. They consist of different ordered spin state arrangements of high-, intermediate-, and low-spin Co3+ of CoO6 octahedra. Phase separation into well separated regions with different spin state order is observed in the antiferromagnetic phases. The unusual strongly anisotropic magnetoresistance and its onset at the FM-AFM phase boundary is explained.
Collapse
Affiliation(s)
- H Luetkens
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
| | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Lancaster T, Blundell SJ, Andreica D, Janoschek M, Roessli B, Gvasaliya SN, Conder K, Pomjakushina E, Brooks ML, Baker PJ, Prabhakaran D, Hayes W, Pratt FL. Magnetism in geometrically frustrated YMnO3 under hydrostatic pressure studied with muon spin relaxation. Phys Rev Lett 2007; 98:197203. [PMID: 17677657 DOI: 10.1103/physrevlett.98.197203] [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] [Received: 10/17/2006] [Indexed: 05/16/2023]
Abstract
The ferroelectromagnet YMnO3 consists of weakly coupled triangular layers of S=2 spins. Below T(N) approximately equal to 70 K muon-spin relaxation data show two oscillatory relaxing signals due to magnetic order, with no purely relaxing signals resolvable (which would require different coexisting spin distributions). The transition temperature T(N) increases with applied hydrostatic pressure, even though the ordered moment decreases. These results suggest that pressure increases both the exchange coupling between the layers and the frustration within the layers.
Collapse
Affiliation(s)
- T Lancaster
- Clarendon Laboratory, Department of Physics, Oxford University, Parks Road, Oxford, OX1 3PU, United Kingdom.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Häfliger P, Podlesnyak A, Conder K, Pomjakushina E, Furrer A. The pseudogap in LSCO-type high-temperature superconductors as seen by neutron crystal-field spectroscopy. PROG SOLID STATE CH 2007. [DOI: 10.1016/j.progsolidstchem.2007.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
47
|
Podlesnyak A, Streule S, Mesot J, Medarde M, Pomjakushina E, Conder K, Tanaka A, Haverkort MW, Khomskii DI. Spin-state transition in LaCoO3: direct neutron spectroscopic evidence of excited magnetic states. Phys Rev Lett 2006; 97:247208. [PMID: 17280319 DOI: 10.1103/physrevlett.97.247208] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Indexed: 05/13/2023]
Abstract
A gradual spin-state transition occurs in LaCoO3 around T approximately 80-120 K, whose detailed nature remains controversial. We studied this transition by means of inelastic neutron scattering and found that with increasing temperature an excitation at approximately 0.6 meV appears, whose intensity increases with temperature, following the bulk magnetization. Within a model including crystal-field interaction and spin-orbit coupling, we interpret this excitation as originating from a transition between thermally excited states located about 120 K above the ground state. We further discuss the nature of the magnetic excited state in terms of intermediate-spin (t(2g)(5)e(g)(1), S=1) versus high-spin (t(2g)(4)e(g)(2), S=2) states. Since the g factor obtained from the field dependence of the inelastic neutron scattering is g approximately 3, the second interpretation is definitely favored.
Collapse
Affiliation(s)
- A Podlesnyak
- Laboratory for Neutron Scattering, ETH Zürich Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Conder K, Pomjakushina E, Pomjakushin V, Stingaciu M, Streule S, Podlesnyak A. Oxygen isotope effect on metal-insulator transition in layered cobaltites RBaCo 2O 5.5 (R = Pr, Dy, Ho and Y). J Phys Condens Matter 2005; 17:5813-5820. [PMID: 32397050 DOI: 10.1088/0953-8984/17/37/016] [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] [Indexed: 06/11/2023]
Abstract
Both differential scanning calorimetry and powder neutron diffraction have been applied to investigate an oxygen isotope effect on the metal-insulator (MI) transition in layered cobaltites RBaCo2O5.5 (R = Pr, Dy, Ho and Y). For all the compounds it was found that 18O substitution increases the transition temperature TMI by about 2 K. A small negative isotope-effect coefficient α0∼-0.06 indicates that a delocalization of the pd σ holes in the Co3+ high spin state (rather than a spin-state transition) can be responsible for the MI transition, in agreement with density-functional calculations (Wu 2003 J. Phys.: Condens. Matter 15 503).
Collapse
Affiliation(s)
- K Conder
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | | | | | | | | | | |
Collapse
|
49
|
Bychkov GL, Shiryaev SV, Soldatov AG, Shestak AS, Barilo SN, Sheptyakov DV, Conder K, Pomjakushina E, Podlesnyak A, Furrer A, Bruetsch R. Crystal growth features and properties of layered rare earth and barium cobaltates. Cryst Res Technol 2005. [DOI: 10.1002/crat.200410356] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
50
|
Khasanov R, Eshchenko DG, Luetkens H, Morenzoni E, Prokscha T, Suter A, Garifianov N, Mali M, Roos J, Conder K, Keller H. Direct observation of the oxygen isotope effect on the in-plane magnetic field penetration depth in optimally doped YBa2Cu3O7-delta. Phys Rev Lett 2004; 92:057602. [PMID: 14995343 DOI: 10.1103/physrevlett.92.057602] [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: 05/20/2003] [Indexed: 05/24/2023]
Abstract
We report the first direct observation of the oxygen-isotope ((16)O/(18)O) effect on the in-plane penetration depth lambda(ab) in a nearly optimally doped YBa(2)Cu(3)O(7-delta) film using the novel low-energy muon-spin rotation technique. Spin-polarized low-energy muons are implanted in the film at a known depth z beneath the surface and process in the local magnetic field B(z). This feature allows us to measure directly the profile B(z) of the magnetic field inside the superconducting film in the Meissner state and to make a straightforward determination of lambda(ab). A substantial isotope shift Delta lambda(ab)/lambda(ab)=2.8(1.0)% at 4 K is observed, implying that the in-plane effective supercarrier mass m*(ab) is oxygen-isotope dependent with Delta m*(ab)/m*(ab)=5.5(2.0)%. These results are in good agreement with magnetization measurements on powder samples.
Collapse
Affiliation(s)
- R Khasanov
- Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057, Switzerland.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|