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P AM, Joseph T. Anti-matching effect in a two dimensional driven vortex lattice in the presence of periodic pinning. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:495401. [PMID: 39191271 DOI: 10.1088/1361-648x/ad743c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 08/27/2024] [Indexed: 08/29/2024]
Abstract
The dynamics of a driven superconducting vortex lattice in a two-dimensional (2D) periodic potential of square symmetry is studied using Brownian dynamics simulations. The range and strength of the vortex-substrate interaction are taken to be of the same order as that of the vortex-vortex interaction. The matching effect in a driven vortex lattice in the presence of a periodic array of pinning centers refers to the enhanced resistance to the vortex lattice motion when the ratio of the number of vortices to the number of pinning centers (called the filling fraction) takes simple fractional values. In particular, one expects a pronounced matching effect when the filling fraction is one. Contrary to this expectation, a drop in the vortex lattice mobility is observed as the filling fraction is increased from value one. This anti-matching effect can be understood in terms of the structural change in the vortex lattice as the filling fraction is varied. The dip observed in vortex mobility as a function of temperature when the filling fraction equals one (Joseph T 2020PhysicaA556124737), is studied for other values of filling above and below one. The behavior is found to persist for other fillings as well and is associated with the melting of the vortex lattice. The temperature at which the lattice melts is found to increase with drive and explains the shift in the temperature at which mobility is a minimum, locally.
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Affiliation(s)
- Akhilesh M P
- Department of Physics, BITS-Pilani, K K Birla Goa Campus, Zuarinagar Goa-403726, India
| | - Toby Joseph
- Department of Physics, BITS-Pilani, K K Birla Goa Campus, Zuarinagar Goa-403726, India
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Iida K, Hänisch J, Kondo K, Chen M, Hatano T, Wang C, Saito H, Hata S, Ikuta H. High J c and low anisotropy of hydrogen doped NdFeAsO superconducting thin film. Sci Rep 2021; 11:5636. [PMID: 33707638 PMCID: PMC7952916 DOI: 10.1038/s41598-021-85216-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 02/25/2021] [Indexed: 11/30/2022] Open
Abstract
The recent realisations of hydrogen doped LnFeAsO (Ln = Nd and Sm) superconducting epitaxial thin films call for further investigation of their structural and electrical transport properties. Here, we report on the microstructure of a NdFeAs(O,H) epitaxial thin film and its temperature, field, and orientation dependencies of the resistivity and the critical current density Jc. The superconducting transition temperature Tc is comparable to NdFeAs(O,F). Transmission electron microscopy investigation supported that hydrogen is homogenously substituted for oxygen. A high self-field Jc of over 10 MA/cm2 was recorded at 5 K, which is likely to be caused by a short London penetration depth. The anisotropic Ginzburg-Landau scaling for the angle dependence of Jc yielded temperature-dependent scaling parameters γJ that decreased from 1.6 at 30 K to 1.3 at 5 K. This is opposite to the behaviour of NdFeAs(O,F). Additionally, γJ of NdFeAs(O,H) is smaller than that of NdFeAs(O,F). Our results indicate that heavily electron doping by means of hydrogen substitution for oxygen in LnFeAsO is highly beneficial for achieving high Jc with low anisotropy without compromising Tc, which is favourable for high-field magnet applications.
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Affiliation(s)
- Kazumasa Iida
- Department of Materials Physics, Nagoya University, Chikusa-ku, Nagoya, 464-8603, Japan.
- JST CREST, Kawaguchi, Saitama, 332-0012, Japan.
| | - Jens Hänisch
- Institute for Technical Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Keisuke Kondo
- Department of Materials Physics, Nagoya University, Chikusa-ku, Nagoya, 464-8603, Japan
| | - Mingyu Chen
- Department of Materials Physics, Nagoya University, Chikusa-ku, Nagoya, 464-8603, Japan
| | - Takafumi Hatano
- Department of Materials Physics, Nagoya University, Chikusa-ku, Nagoya, 464-8603, Japan
- JST CREST, Kawaguchi, Saitama, 332-0012, Japan
| | - Chao Wang
- The Ultramicroscopy Research Center, Kyushu University, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Hikaru Saito
- Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan
- JST CREST, Kawaguchi, Saitama, 332-0012, Japan
| | - Satoshi Hata
- The Ultramicroscopy Research Center, Kyushu University, Nishi-ku, Fukuoka, 819-0395, Japan
- Faculty of Engineering Sciences, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan
- JST CREST, Kawaguchi, Saitama, 332-0012, Japan
| | - Hiroshi Ikuta
- Department of Materials Physics, Nagoya University, Chikusa-ku, Nagoya, 464-8603, Japan
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Tarantini C, Pak C, Su YF, Hellstrom EE, Larbalestier DC, Kametani F. Effect of heat treatments on superconducting properties and connectivity in K-doped BaFe 2As 2. Sci Rep 2021; 11:3143. [PMID: 33542331 PMCID: PMC7862683 DOI: 10.1038/s41598-021-82325-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 01/18/2021] [Indexed: 11/16/2022] Open
Abstract
Fe-based superconductors and in particular K-doped BaFe2As2 (K-Ba122) are materials of interest for possible future high-field applications. However the critical current density (Jc) in polycrystalline Ba122 is still quite low and connectivity issues are suspected to be responsible. In this work we investigated the properties of high-purity, carefully processed, K-Ba122 samples synthesized with two separate heat treatments at various temperatures between 600 and 825 °C. We performed specific heat characterization and Tc-distribution analysis up to 16 T and we compared them with magnetic Tc and Jc characterizations, and transmission-electron-microscopy (TEM) microstructures. We found no direct correlation between the magnetic Tc and Jc, whereas the specific heat Tc-distributions did provide valuable insights. In fact the best Jc-performing sample, heat treated first at 750 °C and then at 600 °C, has the peak of the Tc-distributions at the highest temperatures and the least field sensitivity, thus maximizing Hc2. We also observed that the magnetic Tc onset was always significantly lower than the specific heat Tc: although we partially ascribe the lower magnetization Tc to the small grain size (< λ, the penetration depth) of the K-Ba122 phase, this behaviour also implies the presence of some grain-boundary barriers to current flow. Comparing the Tc-distribution with Jc, our systematic synthesis study reveals that increasing the first heat treatment above 750 °C or the second one above 600 °C significantly compromises the connectivity and suppresses the vortex pinning properties. We conclude that high-purity precursors and clean processing are not yet enough to overcome all Jc limitations. However, our study suggests that a higher temperature Tc-distribution, a larger Hc2 and a better connectivity could be achieved by lowering the second heat treatment temperature below 600 °C thus enhancing, as a consequence, Jc.
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Affiliation(s)
- Chiara Tarantini
- Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA.
| | - Chongin Pak
- Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - Yi-Feng Su
- Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA.,Oak Ridge National Laboratory, Oak Ridge, USA
| | - Eric E Hellstrom
- Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - David C Larbalestier
- Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - Fumitake Kametani
- Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
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Kauffmann-Weiss S, Iida K, Tarantini C, Boll T, Schneider R, Ohmura T, Matsumoto T, Hatano T, Langer M, Meyer S, Jaroszynski J, Gerthsen D, Ikuta H, Holzapfel B, Hänisch J. Microscopic origin of highly enhanced current carrying capabilities of thin NdFeAs(O,F) films. NANOSCALE ADVANCES 2019; 1:3036-3048. [PMID: 36133600 PMCID: PMC9417295 DOI: 10.1039/c9na00147f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 06/03/2019] [Indexed: 06/16/2023]
Abstract
Fe-based superconductors present a large variety of compounds whose physical properties strongly depend on the crystal structure and chemical composition. Among them, the so-called 1111 compounds show the highest critical temperature T c in the bulk form. Here we demonstrate the realization of excellent superconducting properties in NdFeAs(O1-x F x ). We systematically investigated the correlation between the microstructure at the nanoscale and superconductivity in an epitaxial 22 nm NdFeAs(O1-x F x ) thin film on a MgO single crystalline substrate (T c = 44.7 K). Atomic resolution analysis of the microstructure by transmission electron microscopy and atom probe tomography identified several defects and other inhomogeneities at the nanoscale that can act as extrinsic pinning centers. X-Ray diffraction and transmission electron microscopy displayed a broad variation of the a-axis lattice parameter either due to a partially strained layer at the interface to the substrate, high local strain at dislocation arrays, mosaicity, or due to composition variation within the film. The electrical transport properties are substantially affected by intrinsic pinning and a matching field corresponding to the film thickness and associated with the Bean-Livingston surface barrier of the surfaces. The thin film showed a self-field critical current density J c(4.2 K) of ∼7.6 MA cm-2 and a record pinning force density of F p ≈ 1 TN m-3 near 35 T for H‖ab at 4.2 K. These investigations highlight the role of the microstructure in fine-tuning and possibly functionalizing the superconductivity of Fe-based superconductors.
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Affiliation(s)
- Sandra Kauffmann-Weiss
- Institute for Technical Physics (ITEP), Karlsruhe Institute of Technology (KIT) 76344 Eggenstein-Leopoldshafen Germany
| | - Kazumasa Iida
- Department of Materials Physics, Nagoya University Furo-cho, Chikusa-ku Nagoya 464-8603 Japan
- Department of Crystalline Materials Science, Nagoya University Furo-cho, Chikusa-ku Nagoya 464-8603 Japan
| | - Chiara Tarantini
- Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University 2031 East Paul Dirac Drive Tallahassee Florida 32310 USA
| | - Torben Boll
- Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology (KIT) 76344 Eggenstein-Leopoldshafen Germany
- Institute for Applied Materials (IAM-WK), Karlsruhe Institute of Technology (KIT) 76344 Karlsruhe Germany
| | - Reinhard Schneider
- Laboratory for Electron Microscopy (LEM), Karlsruhe Institute of Technology (KIT) Engesserstraße 7 76131 Karlsruhe Germany
| | - Taito Ohmura
- Department of Crystalline Materials Science, Nagoya University Furo-cho, Chikusa-ku Nagoya 464-8603 Japan
| | - Takuya Matsumoto
- Department of Materials Physics, Nagoya University Furo-cho, Chikusa-ku Nagoya 464-8603 Japan
| | - Takafumi Hatano
- Department of Materials Physics, Nagoya University Furo-cho, Chikusa-ku Nagoya 464-8603 Japan
- Department of Crystalline Materials Science, Nagoya University Furo-cho, Chikusa-ku Nagoya 464-8603 Japan
| | - Marco Langer
- Institute for Technical Physics (ITEP), Karlsruhe Institute of Technology (KIT) 76344 Eggenstein-Leopoldshafen Germany
| | - Sven Meyer
- Institute for Technical Physics (ITEP), Karlsruhe Institute of Technology (KIT) 76344 Eggenstein-Leopoldshafen Germany
| | - Jan Jaroszynski
- Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University 2031 East Paul Dirac Drive Tallahassee Florida 32310 USA
| | - Dagmar Gerthsen
- Laboratory for Electron Microscopy (LEM), Karlsruhe Institute of Technology (KIT) Engesserstraße 7 76131 Karlsruhe Germany
| | - Hiroshi Ikuta
- Department of Materials Physics, Nagoya University Furo-cho, Chikusa-ku Nagoya 464-8603 Japan
- Department of Crystalline Materials Science, Nagoya University Furo-cho, Chikusa-ku Nagoya 464-8603 Japan
| | - Bernhard Holzapfel
- Institute for Technical Physics (ITEP), Karlsruhe Institute of Technology (KIT) 76344 Eggenstein-Leopoldshafen Germany
| | - Jens Hänisch
- Institute for Technical Physics (ITEP), Karlsruhe Institute of Technology (KIT) 76344 Eggenstein-Leopoldshafen Germany
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Lao M, Hänisch J, Kauffmann-Weiss S, Gehring R, Fillinger H, Drechsler A, Holzapfel B. High current variable temperature electrical characterization system for superconducting wires and tapes with continuous sample rotation in a split coil magnet. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:015106. [PMID: 30709201 DOI: 10.1063/1.5078447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 12/14/2018] [Indexed: 06/09/2023]
Abstract
A new state-of-the-art electrical transport measurement system was developed for the characterization of industrially produced coated conductors (CCs). The current leads are rated to a conduct current of up to 1000 A, which opens up the possibility of measuring the critical current Ic of tapes at a wide range of temperatures. The setup operates in a He-gas flow cryostat that provides stable temperatures between 1.8 and 200 K. The setup is equipped with a split-coil magnet that can apply fields of up to 6 T. A continuous rotation of the sample with respect to the magnetic field with an angular resolution of 0.5° enables characterization of anisotropic Ic of different tapes. In the measured voltage-current curves, weak sample heating mostly occurs from the dissipation in the tape during the Ic transition. It is demonstrated that the system can provide reliable data on the properties of CCs at temperatures lower than 77 K for a magnet design and other applications. The results allow the study of vortex pinning for further prospects of engineering the microstructure of the superconducting layer as well as to assess the performance of various tapes with different architectures to achieve optimum performance at different operating temperatures and magnetic fields.
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Affiliation(s)
- M Lao
- Institute of Technical Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - J Hänisch
- Institute of Technical Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - S Kauffmann-Weiss
- Institute of Technical Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - R Gehring
- Institute of Technical Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - H Fillinger
- Institute of Technical Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - A Drechsler
- Institute of Technical Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - B Holzapfel
- Institute of Technical Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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Vallès F, Palau A, Rouco V, Mundet B, Obradors X, Puig T. Angular flux creep contributions in YBa 2Cu 3O 7-δ nanocomposites from electrical transport measurements. Sci Rep 2018; 8:5924. [PMID: 29651116 PMCID: PMC5897461 DOI: 10.1038/s41598-018-24392-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 03/23/2018] [Indexed: 11/14/2022] Open
Abstract
The shape of the electric-field—current-density (E-J) curve is determined by flux pinning and also by dynamics of vortices. Here, we propose a novel methodology to study the normalized flux creep rate S in YBa2Cu3O7−δ measured from E-J curves obtained by electrical transport measurements that provides a fast and versatile way to foresee the flux magnetic relaxation in films and disentangle angular flux creep contributions by the scaling of the isotropic contribution of S. After a detailed comparison of various pristine and nanocomposite films with differentiated nanostructures, we focus on the roles that intrinsic pinning and stacking faults (YBa2Cu4O8-intergrowths) play when the magnetic field is applied parallel to the superconducting CuO2 planes. This study reveals that the emerging intergrowths provide advanced pinning properties that additionally reduce the thermal activated flux magnetic relaxation. For this purpose, creep analysis becomes a very appropriate tool to elucidate the dominance of the different pinning sites at different regions of the magnetic-field—temperature diagram.
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Affiliation(s)
- F Vallès
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193, Bellaterra, Spain.
| | - A Palau
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193, Bellaterra, Spain
| | - V Rouco
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193, Bellaterra, Spain
| | - B Mundet
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193, Bellaterra, Spain
| | - X Obradors
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193, Bellaterra, Spain
| | - T Puig
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193, Bellaterra, Spain
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Grimaldi G, Leo A, Nigro A, Pace S, Braccini V, Bellingeri E, Ferdeghini C. Angular dependence of vortex instability in a layered superconductor: the case study of Fe(Se,Te) material. Sci Rep 2018; 8:4150. [PMID: 29515198 PMCID: PMC5841287 DOI: 10.1038/s41598-018-22417-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 02/19/2018] [Indexed: 11/09/2022] Open
Abstract
Anisotropy effects on flux pinning and flux flow are strongly effective in cuprate as well as iron-based superconductors due to their intrinsically layered crystallographic structure. However Fe(Se,Te) thin films grown on CaF2 substrate result less anisotropic with respect to all the other iron based superconductors. We present the first study on the angular dependence of the flux flow instability, which occurs in the flux flow regime as a current driven transition to the normal state at the instability point (I*, V*) in the current-voltage characteristics. The voltage jumps are systematically investigated as a function of the temperature, the external magnetic field, and the angle between the field and the Fe(Se,Te) film. The scaling procedure based on the anisotropic Ginzburg-Landau approach is successfully applied to the observed angular dependence of the critical voltage V*. Anyway, we find out that Fe(Se,Te) represents the case study of a layered material characterized by a weak anisotropy of its static superconducting properties, but with an increased anisotropy in its vortex dynamics due to the predominant perpendicular component of the external applied magnetic field. Indeed, I* shows less sensitivity to angle variations, thus being promising for high field applications.
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Affiliation(s)
| | - Antonio Leo
- CNR SPIN, Salerno, Fisciano, 84084, Italy
- Physics Department, University of Salerno, Fisciano, 84084, Italy
| | - Angela Nigro
- CNR SPIN, Salerno, Fisciano, 84084, Italy
- Physics Department, University of Salerno, Fisciano, 84084, Italy
| | - Sandro Pace
- CNR SPIN, Salerno, Fisciano, 84084, Italy
- Physics Department, University of Salerno, Fisciano, 84084, Italy
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