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Jung S, Jang H, Kim J, Park J, Lee S, Seo S, Bauer ED, Park T. A Quenched Disorder in the Quantum-Critical Superconductor CeCoIn 5. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2304837. [PMID: 37985882 PMCID: PMC10767398 DOI: 10.1002/advs.202304837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 10/20/2023] [Indexed: 11/22/2023]
Abstract
Emergent inhomogeneous electronic phases in metallic quantum systems are crucial for understanding high-Tc superconductivity and other novel quantum states. In particular, spin droplets introduced by nonmagnetic dopants in quantum-critical superconductors (QCSs) can lead to a novel magnetic state in superconducting phases. However, the role of disorders caused by nonmagnetic dopants in quantum-critical regimes and their precise relation with superconductivity remain unclear. Here, the systematic evolution of a strong correlation between superconductive intertwined electronic phases and antiferromagnetism in Cd-doped CeCoIn5 is presented by measuring current-voltage characteristics under an external pressure. In the low-pressure coexisting regime where antiferromagnetic (AFM) and superconducting (SC) orders coexist, the critical current (Ic ) is gradually suppressed by the increasing magnetic field, as in conventional type-II superconductors. At pressures higher than the critical pressure where the AFM order disappears, Ic remarkably shows a sudden spike near the irreversible magnetic field. In addition, at high pressures far from the critical pressure point, the peak effect is not suppressed, but remains robust over the whole superconducting region. These results indicate that magnetic islands are protected around dopant sites despite being suppressed by the increasingly correlated effects under pressure, providing a new perspective on the role of quenched disorders in QCSs.
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Affiliation(s)
- Soon‐Gil Jung
- Department of Physics EducationSunchon National UniversitySuncheon57922South Korea
| | - Harim Jang
- Department of PhysicsSungkyunkwan UniversitySuwon16419South Korea
| | - Jihyun Kim
- Department of PhysicsSungkyunkwan UniversitySuwon16419South Korea
| | - Jin‐Hong Park
- Department of PhysicsSungkyunkwan UniversitySuwon16419South Korea
| | - Sangyun Lee
- Los Alamos National LaboratoryAlamosNM87545USA
| | - Soonbeom Seo
- Department of PhysicsChangwon National UniversityChangwon51140South Korea
| | | | - Tuson Park
- Center for Quantum Materials and Superconductivity (CQMS)Department of PhysicsSungkyunkwan UniversitySuwon16419South Korea
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2
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Rivasto E, Aye MM, Huhtinen H, Paturi P. Enhanced critical current density in optimized high-temperature superconducting bilayer thin films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 36:135702. [PMID: 38100827 DOI: 10.1088/1361-648x/ad162c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 12/15/2023] [Indexed: 12/17/2023]
Abstract
The superconducting and structural properties of bilayer thin films based on YBa2Cu3O7-x / YBa2Cu3O7-x+6%BaZrO3heterstructures have been studied. In a broad range of magnetic field strengths and temperatures, the optimal bilayer film comprises 30% YBCO at the substrate interface and 70% YBCO+6%BZO on the top. The critical current density measured for the optimal bilayer structure is shown to outperform the corresponding single layer films up to almost 60%. The obtained results are comprehensively discussed in the light of our previously published theoretical framework (Rivastoet al2023J. Phys.: Condens. Matter35075701:1-10). We conclude that the bilayering provides an efficient and easily applicable way to further increase the performance and applicability of high-temperature superconductors in various applications. Consequently, the bilayer films should be seriously considered as candidates for the upcoming generation of coated conductors.
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Affiliation(s)
- E Rivasto
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
| | - M M Aye
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
- University of Turku Graduate School (UTUGS), University of Turku, FI-20014 Turku, Finland
| | - H Huhtinen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
| | - P Paturi
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
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3
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Troyan IA, Semenok DV, Ivanova AG, Sadakov AV, Zhou D, Kvashnin AG, Kruglov IA, Sobolevskiy OA, Lyubutina MV, Perekalin DS, Helm T, Tozer SW, Bykov M, Goncharov AF, Pudalov VM, Lyubutin IS. Non-Fermi-Liquid Behavior of Superconducting SnH 4. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2303622. [PMID: 37626451 PMCID: PMC10602579 DOI: 10.1002/advs.202303622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 07/18/2023] [Indexed: 08/27/2023]
Abstract
The chemical interaction of Sn with H2 by X-ray diffraction methods at pressures of 180-210 GPa is studied. A previously unknown tetrahydride SnH4 with a cubic structure (fcc) exhibiting superconducting properties below TC = 72 K is obtained; the formation of a high molecular C2/m-SnH14 superhydride and several lower hydrides, fcc SnH2 , and C2-Sn12 H18 , is also detected. The temperature dependence of critical current density JC (T) in SnH4 yields the superconducting gap 2Δ(0) = 21.6 meV at 180 GPa. SnH4 has unusual behavior in strong magnetic fields: B,T-linear dependences of magnetoresistance and the upper critical magnetic field BC2 (T) ∝ (TC - T). The latter contradicts the Wertheimer-Helfand-Hohenberg model developed for conventional superconductors. Along with this, the temperature dependence of electrical resistance of fcc SnH4 in non-superconducting state exhibits a deviation from what is expected for phonon-mediated scattering described by the Bloch-Grüneisen model and is beyond the framework of the Fermi liquid theory. Such anomalies occur for many superhydrides, making them much closer to cuprates than previously believed.
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Affiliation(s)
- Ivan A. Troyan
- Shubnikov Institute of CrystallographyFederal Scientific Research Center Crystallography and PhotonicsRussian Academy of Sciences59 Leninsky ProspektMoscow119333Russia
| | - Dmitrii V. Semenok
- Center for High Pressure Science and Technology Advanced Research (HPSTAR)Beijing100193China
| | - Anna G. Ivanova
- Shubnikov Institute of CrystallographyFederal Scientific Research Center Crystallography and PhotonicsRussian Academy of Sciences59 Leninsky ProspektMoscow119333Russia
| | - Andrey V. Sadakov
- V. L. Ginzburg Center for High‐Temperature Superconductivity and Quantum Materials P. N. Lebedev Physical InstituteRussian Academy of SciencesMoscow119991Russia
| | - Di Zhou
- Center for High Pressure Science and Technology Advanced Research (HPSTAR)Beijing100193China
| | - Alexander G. Kvashnin
- Skolkovo Institute of Science and TechnologyBolshoy Boulevard, 30/1Moscow121205Russia
| | - Ivan A. Kruglov
- Center for Fundamental and Applied ResearchDukhov Research Institute of Automatics (VNIIA)st. Sushchevskaya, 22Moscow127055Russia
- Laboratory of Computational Materials DiscoveryMoscow Institute of Physics and Technology9 Institutsky LaneDolgoprudny141700Russia
| | - Oleg A. Sobolevskiy
- V. L. Ginzburg Center for High‐Temperature Superconductivity and Quantum Materials P. N. Lebedev Physical InstituteRussian Academy of SciencesMoscow119991Russia
| | - Marianna V. Lyubutina
- Shubnikov Institute of CrystallographyFederal Scientific Research Center Crystallography and PhotonicsRussian Academy of Sciences59 Leninsky ProspektMoscow119333Russia
| | - Dmitry S. Perekalin
- A.N. Nesmeyanov Institute of Organoelement CompoundsRussian Academy of Sciences28 Vavilova str.Moscow119334Russia
| | - Toni Helm
- Hochfeld‐Magnetlabor Dresden (HLD‐EMFL) and Würzburg‐Dresden Cluster of ExcellenceHelmholtz‐Zentrum Dresden‐Rossendorf (HZDR)01328DresdenGermany
| | - Stanley W. Tozer
- National High Magnetic Field LaboratoryFlorida State UniversityTallahasseeFlorida32310USA
| | - Maxim Bykov
- Institute of Inorganic ChemistryUniversity of Cologne50939CologneGermany
| | - Alexander F. Goncharov
- Earth and Planets LaboratoryCarnegie Institution for Science5241 Broad Branch Road NWWashingtonDC20015USA
| | - Vladimir M. Pudalov
- V. L. Ginzburg Center for High‐Temperature Superconductivity and Quantum Materials P. N. Lebedev Physical InstituteRussian Academy of SciencesMoscow119991Russia
- HSE Tikhonov Moscow Institute of Electronics and Mathematics National Research University Higher School of Economics20 Myasnitskaya ulitsaMoscow101000Russia
| | - Igor S. Lyubutin
- Shubnikov Institute of CrystallographyFederal Scientific Research Center Crystallography and PhotonicsRussian Academy of Sciences59 Leninsky ProspektMoscow119333Russia
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4
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Tuomola A, Rivasto E, Aye MM, Zhao Y, Huhtinen H, Paturi P. Defining optimal thickness for maximal self-fieldJcin YBCO/CeO 2multilayers grown on buffered metal. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:475001. [PMID: 37552999 DOI: 10.1088/1361-648x/acee3d] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 08/08/2023] [Indexed: 08/10/2023]
Abstract
The effect of multilayering YBa2Cu3O6+x(YBCO) thin films with sequentially deposited CeO2layers between YBCO layers grown on buffered metallic template is investigated to optimize the self-field critical current densityJc(0). We have obtained that the improvement inJc(0)clearly depends on the YBCO layer thickness and temperature, where at high temperatureJc(0)can be increased even 50% when compared with the single layer YBCO films. Based on our experimental results and theoretical approach to the growth mechanism during multilayer deposition, we have defined a critical thickness for the YBCO layer, where the maximal self-fieldJc(0)is strongly related to the competing issues between the uniform and nonuniform strain relaxation and the formation of dislocations and other defects during the film growth. Our results can be directly utilized in the future coated conductor technology, when maximizing the overall in-fieldJc(B)by combining both the optimal crystalline quality and flux pinning properties typically in bilayer film structures.
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Affiliation(s)
- A Tuomola
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
| | - E Rivasto
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
- University of Turku Graduate School (UTUGS), University of Turku, FI-20014 Turku, Finland
| | - M M Aye
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
- University of Turku Graduate School (UTUGS), University of Turku, FI-20014 Turku, Finland
| | - Y Zhao
- School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - H Huhtinen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
| | - P Paturi
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
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5
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Talantsev EF, Valova-Zaharevskaya EG, Deryagina IL, Popova EN. Characteristic Length for Pinning Force Density in Nb 3Sn. MATERIALS (BASEL, SWITZERLAND) 2023; 16:5185. [PMID: 37512460 PMCID: PMC10383299 DOI: 10.3390/ma16145185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 07/30/2023]
Abstract
The pinning force density, Fp, is one of the main parameters that characterize the resilience of a superconductor to carrying a dissipative-free transport current in an applied magnetic field. Kramer (1973) and Dew-Hughes (1974) proposed a widely used scaling law for this quantity, where one of the parameters is the pinning force density maximum, Fp,max, which represents the maximal performance of a given superconductor in an applied magnetic field at a given temperature. Since the late 1970s to the present, several research groups have reported experimental data on the dependence of Fp,max on the average grain size, d, in Nb3Sn-based conductors. Fp,maxd datasets were analyzed and a scaling law for the dependence Fp,maxd=A×ln1/d+B was proposed. Despite the fact that this scaling law is widely accepted, it has several problems; for instance, according to this law, at T=4.2 K and d≥650 nm, Nb3Sn should lose its superconductivity, which is in striking contrast to experiments. Here, we reanalyzed the full inventory of publicly available Fp,maxd data for Nb3Sn conductors and found that the dependence can be described by the exponential law, in which the characteristic length, δ, varies within a remarkably narrow range of δ=175±13 nm for samples fabricated using different technologies. The interpretation of this result is based on the idea that the in-field supercurrent flows within a thin surface layer (thickness of δ) near grain boundary surfaces (similar to London's law, where the self-field supercurrent flows within a thin surface layer with a thickness of the London penetration depth, λ, and the surface is a superconductor-vacuum surface). An alternative interpretation is that δ represents the characteristic length of the exponential decay flux pinning potential from the dominant defects in Nb3Sn superconductors, which are grain boundaries.
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Affiliation(s)
- Evgeny F Talantsev
- M. N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskaya St., 620108 Ekaterinburg, Russia
- NANOTECH Centre, Ural Federal University, 19 Mira St., 620002 Ekaterinburg, Russia
| | - Evgeniya G Valova-Zaharevskaya
- M. N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskaya St., 620108 Ekaterinburg, Russia
| | - Irina L Deryagina
- M. N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskaya St., 620108 Ekaterinburg, Russia
| | - Elena N Popova
- M. N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskaya St., 620108 Ekaterinburg, Russia
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6
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Talantsev EF. D-Wave Superconducting Gap Symmetry as a Model for Nb1−xMoxB2 (x = 0.25; 1.0) and WB2 Diborides. Symmetry (Basel) 2023. [DOI: 10.3390/sym15040812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
Abstract
Recently, Pei et al. (National Science Review2023, nwad034, 10.1093/nsr/nwad034) reported that ambient pressure β-MoB2 (space group: R3¯m) exhibits a phase transition to α-MoB2 (space group: P6/mmm) at pressure P~70 GPa, which is a high-temperature superconductor exhibiting Tc=32 K at P~110 GPa. Although α-MoB2 has the same crystalline structure as ambient-pressure MgB2 and the superconducting critical temperatures of α-MoB2 and MgB2 are very close, the first-principles calculations show that in α-MoB2, the states near the Fermi level, εF, are dominated by the d-electrons of Mo atoms, while in MgB2, the p-orbitals of boron atomic sheets dominantly contribute to the states near the εF. Recently, Hire et al. (Phys. Rev. B2022, 106, 174515) reported that the P6/mmm-phase can be stabilized at ambient pressure in Nb1−xMoxB2 solid solutions, and that these ternary alloys exhibit Tc~8 K. Additionally, Pei et al. (Sci. China-Phys. Mech. Astron. 2022, 65, 287412) showed that compressed WB2 exhibited Tc~15 K at P~121 GPa. Here, we aimed to reveal primary differences/similarities in superconducting state in MgB2 and in its recently discovered diboride counterparts, Nb1−xMoxB2 and highly-compressed WB2. By analyzing experimental data reported for P6/mmm-phases of Nb1−xMoxB2 (x = 0.25; 1.0) and highly compressed WB2, we showed that these three phases exhibit d-wave superconductivity. We deduced 2Δm(0)kBTc=4.1±0.2 for α-MoB2, 2Δm(0)kBTc=5.3±0.1 for Nb0.75Mo0.25B2, and 2Δm(0)kBTc=4.9±0.2 for WB2. We also found that Nb0.75Mo0.25B2 exhibited high strength of nonadiabaticity, which was quantified by the ratio of TθTF=3.5, whereas MgB2, α-MoB2, and WB2 exhibited TθTF~0.3, which is similar to the TθTF in pnictides, A15 alloys, Heusler alloys, Laves phase compounds, cuprates, and highly compressed hydrides.
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7
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Zhang W, Liu X, Wang L, Tsang CW, Wang Z, Lam ST, Wang W, Xie J, Zhou X, Zhao Y, Wang S, Tallon J, Lai KT, Goh SK. Nodeless Superconductivity in Kagome Metal CsV 3Sb 5 with and without Time Reversal Symmetry Breaking. NANO LETTERS 2023; 23:872-879. [PMID: 36662599 PMCID: PMC9912374 DOI: 10.1021/acs.nanolett.2c04103] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 01/13/2023] [Indexed: 06/17/2023]
Abstract
The kagome metal CsV3Sb5 features an unusual competition between the charge-density-wave (CDW) order and superconductivity. Evidence for time reversal symmetry breaking (TRSB) inside the CDW phase has been accumulating. Hence, the superconductivity in CsV3Sb5 emerges from a TRSB normal state, potentially resulting in an exotic superconducting state. To reveal the pairing symmetry, we first investigate the effect of nonmagnetic impurity. Our results show that the superconducting critical temperature is insensitive to disorder, pointing to conventional s-wave superconductivity. Moreover, our measurements of the self-field critical current (Ic,sf), which is related to the London penetration depth, also confirm conventional s-wave superconductivity with strong coupling. Finally, we measure Ic,sf where the CDW order is removed by pressure and superconductivity emerges from the pristine normal state. Our results show that s-wave gap symmetry is retained, providing strong evidence for the presence of conventional s-wave superconductivity in CsV3Sb5 irrespective of the presence of the TRSB.
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Affiliation(s)
- Wei Zhang
- Department
of Physics, The Chinese University of Hong
Kong, Shatin, Hong Kong, China
| | - Xinyou Liu
- Department
of Physics, The Chinese University of Hong
Kong, Shatin, Hong Kong, China
| | - Lingfei Wang
- Department
of Physics, The Chinese University of Hong
Kong, Shatin, Hong Kong, China
| | - Chun Wai Tsang
- Department
of Physics, The Chinese University of Hong
Kong, Shatin, Hong Kong, China
| | - Zheyu Wang
- Department
of Physics, The Chinese University of Hong
Kong, Shatin, Hong Kong, China
| | - Siu Tung Lam
- Department
of Physics, The Chinese University of Hong
Kong, Shatin, Hong Kong, China
| | - Wenyan Wang
- Department
of Physics, The Chinese University of Hong
Kong, Shatin, Hong Kong, China
| | - Jianyu Xie
- Department
of Physics, The Chinese University of Hong
Kong, Shatin, Hong Kong, China
| | - Xuefeng Zhou
- Department
of Physics, Southern University of Science
and Technology, Shenzhen, Guangdong518055, China
| | - Yusheng Zhao
- Department
of Physics, Southern University of Science
and Technology, Shenzhen, Guangdong518055, China
| | - Shanmin Wang
- Department
of Physics, Southern University of Science
and Technology, Shenzhen, Guangdong518055, China
| | - Jeff Tallon
- Robinson
Institute, Victoria University of Wellington, P.O. Box 600, Wellington6140, New Zealand
| | - Kwing To Lai
- Department
of Physics, The Chinese University of Hong
Kong, Shatin, Hong Kong, China
- Shenzhen
Research Institute, The Chinese University
of Hong Kong, Shatin, Hong Kong, China
| | - Swee K. Goh
- Department
of Physics, The Chinese University of Hong
Kong, Shatin, Hong Kong, China
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8
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Talantsev EF. Quantifying Nonadiabaticity in Major Families of Superconductors. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 13:71. [PMID: 36615981 PMCID: PMC9824585 DOI: 10.3390/nano13010071] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/17/2022] [Accepted: 12/19/2022] [Indexed: 06/17/2023]
Abstract
The classical Bardeen−Cooper−Schrieffer and Eliashberg theories of the electron−phonon-mediated superconductivity are based on the Migdal theorem, which is an assumption that the energy of charge carriers, kBTF, significantly exceeds the phononic energy, ℏωD, of the crystalline lattice. This assumption, which is also known as adiabatic approximation, implies that the superconductor exhibits fast charge carriers and slow phonons. This picture is valid for pure metals and metallic alloys because these superconductors exhibit ℏωDkBTF<0.01. However, for n-type-doped semiconducting SrTiO3, this adiabatic approximation is not valid, because this material exhibits ℏωDkBTF≅50. There is a growing number of newly discovered superconductors which are also beyond the adiabatic approximation. Here, leaving aside pure theoretical aspects of nonadiabatic superconductors, we classified major classes of superconductors (including, elements, A-15 and Heusler alloys, Laves phases, intermetallics, noncentrosymmetric compounds, cuprates, pnictides, highly-compressed hydrides, and two-dimensional superconductors) by the strength of nonadiabaticity (which we defined by the ratio of the Debye temperature to the Fermi temperature, TθTF). We found that the majority of analyzed superconductors fall into the 0.025≤TθTF≤0.4 band. Based on the analysis, we proposed the classification scheme for the strength of nonadiabatic effects in superconductors and discussed how this classification is linked with other known empirical taxonomies in superconductivity.
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Affiliation(s)
- Evgueni F. Talantsev
- M. N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18 S. Kovalevskoy Str., 620108 Ekaterinburg, Russia; ; Tel.: +7-912-676-0374
- NANOTECH Centre, Ural Federal University, 19 Mira Str., 620002 Ekaterinburg, Russia
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9
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Semenok DV, Troyan IA, Sadakov AV, Zhou D, Galasso M, Kvashnin AG, Ivanova AG, Kruglov IA, Bykov AA, Terent'ev KY, Cherepakhin AV, Sobolevskiy OA, Pervakov KS, Seregin AY, Helm T, Förster T, Grockowiak AD, Tozer SW, Nakamoto Y, Shimizu K, Pudalov VM, Lyubutin IS, Oganov AR. Effect of Magnetic Impurities on Superconductivity in LaH 10. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2204038. [PMID: 35829689 DOI: 10.1002/adma.202204038] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/17/2022] [Indexed: 06/15/2023]
Abstract
Polyhydrides are a novel class of superconducting materials with extremely high critical parameters, which is very promising for sensor applications. On the other hand, a complete experimental study of the best so far known superconductor, lanthanum superhydride LaH10 , encounters a serious complication because of the large upper critical magnetic field HC2 (0), exceeding 120-160 T. It is found that partial replacement of La atoms by magnetic Nd atoms results in significant suppression of superconductivity in LaH10 : each at% of Nd causes a decrease in TC by 10-11 K, helping to control the critical parameters of this compound. Strong pulsed magnetic fields up to 68 T are used to study the Hall effect, magnetoresistance, and the magnetic phase diagram of ternary metal polyhydrides for the first time. Surprisingly, (La,Nd)H10 demonstrates completely linear HC2 (T) ∝ |T - TC |, which calls into question the applicability of the Werthamer-Helfand-Hohenberg model for polyhydrides. The suppression of superconductivity in LaH10 by magnetic Nd atoms and the robustness of TC with respect to nonmagnetic impurities (e.g., Y, Al, C) under Anderson's theorem gives new experimental evidence of the isotropic (s-wave) character of conventional electron-phonon pairing in lanthanum decahydride.
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Affiliation(s)
- Dmitrii V Semenok
- Materials Discovery Laboratory, Skolkovo Institute of Science and Technology, Bolshoy Boulevard, 30/1, Moscow, 121205, Russia
| | - Ivan A Troyan
- Shubnikov Institute of Crystallography, Federal Scientific Research Center "Crystallography and Photonics", Russian Academy of Sciences, 59 Leninsky Prospekt, Moscow, 119333, Russia
| | - Andrey V Sadakov
- V.L. Ginzburg Center for High-Temperature Superconductivity and Quantum Materials, P. N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Di Zhou
- Materials Discovery Laboratory, Skolkovo Institute of Science and Technology, Bolshoy Boulevard, 30/1, Moscow, 121205, Russia
| | - Michele Galasso
- Materials Discovery Laboratory, Skolkovo Institute of Science and Technology, Bolshoy Boulevard, 30/1, Moscow, 121205, Russia
| | - Alexander G Kvashnin
- Materials Discovery Laboratory, Skolkovo Institute of Science and Technology, Bolshoy Boulevard, 30/1, Moscow, 121205, Russia
| | - Anna G Ivanova
- Shubnikov Institute of Crystallography, Federal Scientific Research Center "Crystallography and Photonics", Russian Academy of Sciences, 59 Leninsky Prospekt, Moscow, 119333, Russia
| | - Ivan A Kruglov
- Center for Fundamental and Applied Research, Dukhov Research Institute of Automatics (VNIIA), st. Sushchevskaya, 22, Moscow, 127055, Russia
- Laboratory of Computational Materials Discovery, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny, 141700, Russia
| | - Alexey A Bykov
- Crystal Physics Laboratory, NRC "Kurchatov Institute" PNPI, 1, mkr. Orlova roshcha, Gatchina, 188300, Russia
| | - Konstantin Y Terent'ev
- Kirensky Institute of Physics, Siberian Branch of the Russian Academy of Sciences, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russia
| | - Alexander V Cherepakhin
- Kirensky Institute of Physics, Siberian Branch of the Russian Academy of Sciences, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russia
| | - Oleg A Sobolevskiy
- V.L. Ginzburg Center for High-Temperature Superconductivity and Quantum Materials, P. N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Kirill S Pervakov
- V.L. Ginzburg Center for High-Temperature Superconductivity and Quantum Materials, P. N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Alexey Yu Seregin
- Shubnikov Institute of Crystallography, Federal Scientific Research Center "Crystallography and Photonics", Russian Academy of Sciences, 59 Leninsky Prospekt, Moscow, 119333, Russia
- Synchrotron radiation source "KISI-Kurchatov", National Research Center "Kurchatov Institute", Moscow, 123182, Russia
| | - Toni Helm
- Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328, Dresden, Germany
| | - Tobias Förster
- Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328, Dresden, Germany
| | - Audrey D Grockowiak
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
- Brazilian Synchrotron Light Laboratory (LNLS/Sirius), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, 13083-100, Brazil
| | - Stanley W Tozer
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - Yuki Nakamoto
- KYOKUGEN, Graduate School of Engineering Science, Osaka University, Machikaneyamacho 1-3, Toyonaka, Osaka, 560-8531, Japan
| | - Katsuya Shimizu
- KYOKUGEN, Graduate School of Engineering Science, Osaka University, Machikaneyamacho 1-3, Toyonaka, Osaka, 560-8531, Japan
| | - Vladimir M Pudalov
- V.L. Ginzburg Center for High-Temperature Superconductivity and Quantum Materials, P. N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991, Russia
- HSE Tikhonov Moscow Institute of Electronics and Mathematics, National Research University Higher School of Economics, 20 Myasnitskaya ulitsa, Moscow, 101000, Russia
| | - Igor S Lyubutin
- Shubnikov Institute of Crystallography, Federal Scientific Research Center "Crystallography and Photonics", Russian Academy of Sciences, 59 Leninsky Prospekt, Moscow, 119333, Russia
| | - Artem R Oganov
- Materials Discovery Laboratory, Skolkovo Institute of Science and Technology, Bolshoy Boulevard, 30/1, Moscow, 121205, Russia
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10
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Talantsev EF. Method to extracting the penetration field in superconductors from DC magnetization data. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:053912. [PMID: 35649804 DOI: 10.1063/5.0081288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 05/04/2022] [Indexed: 06/15/2023]
Abstract
The lower critical field, Bc1, is one of the fundamental quantities of a superconductor that directly manifests the Cooper pair bulk density in the material. Although this field can be measured using several techniques, the most conventional method is to calculate this field from the experimentally measured DC penetration field, Bp, which is defined as the starting point of the deviation of the DC magnetization curve, M(Bappl), from a linear dependence. Surprisingly, we found no mathematical routine that describes how this starting point of deviation can be found. Here, we propose the extraction of Bp from the fit of the M(Bappl) dataset to the power law, where the threshold criterion Mc can be established by a convention. The advantage of this approach is that the procedure extracts one additional characteristic parameter: the power-law exponent. We demonstrated the applicability of this approach to polycrystalline ThIr3, WB4.2, BaTi2Bi2O, and Th4H15; thin films of Pb and MgB2; and Nb single crystal. In most reports, Bc1(T) analysis is limited by the extraction of the London penetration depth. We advanced the analysis to extract primary thermodynamic superconducting parameters [i.e., the ground state superconducting energy gap, Δ(0); the relative jump in electronic specific heat at transition temperature, ΔCγTc; and the gap-to-transition temperature ratio, 2Δ0kBTc] from Bc1(T) data. This extraction was performed for Nb, ThIr3, TaRh2B2, and NbRh2B2.
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Affiliation(s)
- Evgueni F Talantsev
- M.N. Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskoy St., Ekaterinburg 620108, Russia
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11
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Superconductivity emerging from a stripe charge order in IrTe 2 nanoflakes. Nat Commun 2021; 12:3157. [PMID: 34039981 PMCID: PMC8154908 DOI: 10.1038/s41467-021-23310-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 04/21/2021] [Indexed: 11/09/2022] Open
Abstract
Superconductivity in the vicinity of a competing electronic order often manifests itself with a superconducting dome, centered at a presumed quantum critical point in the phase diagram. This common feature, found in many unconventional superconductors, has supported a prevalent scenario in which fluctuations or partial melting of a parent order are essential for inducing or enhancing superconductivity. Here we present a contrary example, found in IrTe2 nanoflakes of which the superconducting dome is identified well inside the parent stripe charge ordering phase in the thickness-dependent phase diagram. The coexisting stripe charge order in IrTe2 nanoflakes significantly increases the out-of-plane coherence length and the coupling strength of superconductivity, in contrast to the doped bulk IrTe2. These findings clarify that the inherent instabilities of the parent stripe phase are sufficient to induce superconductivity in IrTe2 without its complete or partial melting. Our study highlights the thickness control as an effective means to unveil intrinsic phase diagrams of correlated van der Waals materials. Superconductivity often appears due to suppression of competing electronic orders. Here, the authors present a contrary example showing a superconducting dome inside the parent phase with a stripe charge order in IrTe2 nanoflakes and identify their unusual superconducting properties.
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12
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Collomb D, Zhang M, Yuan W, Bending SJ. Imaging of Strong Nanoscale Vortex Pinning in GdBaCuO High-Temperature Superconducting Tapes. NANOMATERIALS 2021; 11:nano11051082. [PMID: 33922201 PMCID: PMC8145501 DOI: 10.3390/nano11051082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/09/2021] [Accepted: 04/17/2021] [Indexed: 11/16/2022]
Abstract
The high critical current density of second-generation high-temperature superconducting (2G-HTS) tapes is the result of the systematic optimisation of the pinning landscape for superconducting vortices through careful engineering of the size and density of defects and non-superconducting second phases. Here, we use scanning Hall probe microscopy to conduct a vortex-resolved study of commercial GdBaCuO tapes in low fields for the first time and complement this work with “local” magnetisation and transport measurements. Magnetic imaging reveals highly disordered vortex patterns reflecting the presence of strong pinning from a dense distribution of nanoscale Gd2O3 second-phase inclusions in the superconducting film. However, we find that the measured vortex profiles are unexpectedly broad, with full-width-half-maxima typically of 6 μm, and exhibit almost no temperature dependence in the range 10–85 K. Since the lateral displacements of pinned vortex cores are not expected to exceed the superconducting layer thickness, this suggests that the observed broadening is caused by the disruption of the circulating supercurrents due to the high density of nanoscale pinning sites. Deviations of our local magnetisation data from an accepted 2D Bean critical state model also indicate that critical state profiles relax quite rapidly by flux creep. Our measurements provide important information about the role second-phase defects play in enhancing the critical current in these tapes and demonstrate the power of magnetic imaging as a complementary tool in the optimisation of vortex pinning phenomena in 2G-HTS tapes.
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Affiliation(s)
- David Collomb
- Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK;
- Correspondence:
| | - Min Zhang
- Applied Superconductivity Laboratory, Department of Electronics and Electrical Engineering, University of Strathclyde, Glasgow G1 1XQ, UK; (M.Z.); (W.Y.)
| | - Weijia Yuan
- Applied Superconductivity Laboratory, Department of Electronics and Electrical Engineering, University of Strathclyde, Glasgow G1 1XQ, UK; (M.Z.); (W.Y.)
| | - Simon J. Bending
- Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK;
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13
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Ultra-high critical current densities of superconducting YBa 2Cu 3O 7-δ thin films in the overdoped state. Sci Rep 2021; 11:8176. [PMID: 33854183 PMCID: PMC8047038 DOI: 10.1038/s41598-021-87639-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 03/24/2021] [Indexed: 02/02/2023] Open
Abstract
The functional properties of cuprates are strongly determined by the doping state and carrier density. We present an oxygen doping study of YBa2Cu3O7-δ (YBCO) thin films from underdoped to overdoped state, correlating the measured charge carrier density, [Formula: see text], the hole doping, p, and the critical current density, [Formula: see text]. Our results show experimental demonstration of strong increase of [Formula: see text] with [Formula: see text], up to Quantum Critical Point (QCP), due to an increase of the superconducting condensation energy. The ultra-high [Formula: see text] achieved, 90 MA cm-2 at 5 K corresponds to about a fifth of the depairing current, i.e. a value among the highest ever reported in YBCO films. The overdoped regime is confirmed by a sudden increase of [Formula: see text], associated to the reconstruction of the Fermi-surface at the QCP. Overdoping YBCO opens a promising route to extend the current carrying capabilities of rare-earth barium copper oxide (REBCO) coated conductors for applications.
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14
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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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15
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He X, Wen Y, Zhang C, Lai Z, Chudnovsky EM, Zhang X. Enhancement of critical current density in a superconducting NbSe 2 step junction. NANOSCALE 2020; 12:12076-12082. [PMID: 32478360 DOI: 10.1039/d0nr03902k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We investigate the transport properties of a NbSe2 nanodevice consisting of a thin region, a thick region and a step junction. The superconducting critical current density of each region of the nanodevice has been studied as a function of temperature and magnetic field. We find that the critical current density has similar values for both the thin and thick regions away from the junction, while the critical current density of the thin region of the junction increases to approximately 1.8 times as compared with the values obtained for the other regions. We attribute such an enhancement of critical current density to the vortex pinning at the surface step. Our study verifies the enhancement of the critical current density by the geometrical-type pinning and sheds light on the application of 2D superconductors.
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Affiliation(s)
- Xin He
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
| | - Yan Wen
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
| | - Chenhui Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
| | - Zhiping Lai
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
| | - Eugene M Chudnovsky
- Physics Department, Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589, USA.
| | - Xixiang Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
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16
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Nobukane H, Yanagihara K, Kunisada Y, Ogasawara Y, Isono K, Nomura K, Tanahashi K, Nomura T, Akiyama T, Tanda S. Co-appearance of superconductivity and ferromagnetism in a Ca 2RuO 4 nanofilm crystal. Sci Rep 2020; 10:3462. [PMID: 32103095 PMCID: PMC7044234 DOI: 10.1038/s41598-020-60313-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 02/10/2020] [Indexed: 12/03/2022] Open
Abstract
By tuning the physical and chemical pressures of layered perovskite materials we can realize the quantum states of both superconductors and insulators. By reducing the thickness of a layered crystal to a nanometer level, a nanofilm crystal can provide novel quantum states that have not previously been found in bulk crystals. Here we report the realization of high-temperature superconductivity in Ca2RuO4 nanofilm single crystals. Ca2RuO4 thin film with the highest transition temperature Tc (midpoint) of 64 K exhibits zero resistance in electric transport measurements. The superconducting critical current exhibited a logarithmic dependence on temperature and was enhanced by an external magnetic field. Magnetic measurements revealed a ferromagnetic transition at 180 K and diamagnetic magnetization due to superconductivity. Our results suggest the co-appearance of superconductivity and ferromagnetism in Ca2RuO4 nanofilm crystals. We also found that the induced bias current and the tuned film thickness caused a superconductor-insulator transition. The fabrication of micro-nanocrystals made of layered material enables us to discuss rich superconducting phenomena in ruthenates.
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Affiliation(s)
- Hiroyoshi Nobukane
- Department of Physics, Hokkaido University, Sapporo, 060-0810, Japan. .,Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo, 060-8628, Japan.
| | - Kosei Yanagihara
- Department of Physics, Hokkaido University, Sapporo, 060-0810, Japan
| | - Yuji Kunisada
- Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, Sapporo, 060-0828, Japan
| | - Yunito Ogasawara
- Department of Physics, Hokkaido University, Sapporo, 060-0810, Japan
| | - Kakeru Isono
- Department of Physics, Hokkaido University, Sapporo, 060-0810, Japan
| | - Kazushige Nomura
- Department of Physics, Hokkaido University, Sapporo, 060-0810, Japan
| | - Keita Tanahashi
- Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, Sapporo, 060-0828, Japan
| | - Takahiro Nomura
- Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, Sapporo, 060-0828, Japan
| | - Tomohiro Akiyama
- Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo, 060-8628, Japan.,Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, Sapporo, 060-0828, Japan
| | - Satoshi Tanda
- Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo, 060-8628, Japan.,Department of Applied Physics, Hokkaido University, Sapporo, 060-8628, Japan
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17
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Talantsev EF, Mataira RC, Crump WP. Classifying superconductivity in Moiré graphene superlattices. Sci Rep 2020; 10:212. [PMID: 31937784 PMCID: PMC6959361 DOI: 10.1038/s41598-019-57055-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 12/20/2019] [Indexed: 11/08/2022] Open
Abstract
Several research groups have reported on the observation of superconductivity in bilayer graphene structures where single atomic layers of graphene are stacked and then twisted at angles θ forming Moiré superlattices. The characterization of the superconducting state in these 2D materials is an ongoing task. Here we investigate the pairing symmetry of bilayer graphene Moiré superlattices twisted at θ = 1.05°, 1.10° and 1.16° for carrier doping states varied in the range of n = (0.5 - 1.5) · 1012 cm-2 (where superconductivity can be realized) by analyzing the temperature dependence of the upper critical field Bc2(T) and the self-field critical current Jc(sf,T) within currently available models - all of which start from phonon-mediated BCS theory - for single- and two-band s-, d-, p- and d + id-wave gap symmetries. Extracted superconducting parameters show that only s-wave and a specific kind of p-wave symmetries are likely to be dominant in bilayer graphene Moiré superlattices. More experimental data is required to distinguish between the s- and remaining p-wave symmetries as well as the suspected two-band superconductivity in these 2D superlattices.
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Affiliation(s)
- E F Talantsev
- M.N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskoy St., Ekaterinburg, 620108, Russia.
- NANOTECH Centre, Ural Federal University, 19 Mira St., Ekaterinburg, 620002, Russia.
| | - R C Mataira
- Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5040, New Zealand
| | - W P Crump
- Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5040, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, P.O. Box 33436, Lower Hutt, 5046, New Zealand
- Aalto University, Foundation sr, PO Box 11000, FI-00076, AALTO, Finland
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18
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Talantsev EF. DC Self-Field Critical Current in Superconductor Dirac-Cone Material/Superconductor Junctions. NANOMATERIALS (BASEL, SWITZERLAND) 2019; 9:E1554. [PMID: 31683857 PMCID: PMC6915389 DOI: 10.3390/nano9111554] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/24/2019] [Accepted: 10/29/2019] [Indexed: 11/18/2022]
Abstract
Recently, several research groups have reported on anomalous enhancement of the self-field critical currents, Ic(sf,T), at low temperatures in superconductor/Dirac-cone material/superconductor (S/DCM/S) junctions. Some papers attributed the enhancement to the low-energy Andreev bound states arising from winding of the electronic wave function around DCM. In this paper, Ic(sf,T) in S/DCM/S junctions have been analyzed by two approaches: modified Ambegaokar-Baratoff and ballistic Titov-Beenakker models. It is shown that the ballistic model, which is traditionally considered to be a basic model to describe Ic(sf,T) in S/DCM/S junctions, is an inadequate tool to analyze experimental data from these type of junctions, while Ambegaokar-Baratoff model, which is generally considered to be a model for Ic(sf,T) in superconductor/insulator/superconductor junctions, provides good experimental data description. Thus, there is a need to develop a new model for self-field critical currents in S/DCM/S systems.
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Affiliation(s)
- Evgueni F Talantsev
- M. N. Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskoy St., Ekaterinburg 620108, Russia.
- NANOTECH Centre, Ural Federal University, 19 Mira St., Ekaterinburg 620002, Russia.
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19
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Abstract
The possibility of p-wave pairing in superconductors has been proposed more than five decades ago, but has not yet been convincingly demonstrated. One difficulty is that some p-wave states are thermodynamically indistinguishable from s-wave, while others are very similar to d-wave states. Here we studied the self-field critical current of NdFeAs(O,F) thin films in order to extract absolute values of the London penetration depth, the superconducting energy gap, and the relative jump in specific heat at the superconducting transition temperature, and find that all the deduced physical parameters strongly indicate that NdFeAs(O,F) is a bulk p-wave superconductor. Further investigation revealed that single atomic layer FeSe also shows p-wave pairing. In an attempt to generalize these findings, we re-examined the whole inventory of superfluid density measurements in iron-based superconductors and show quite generally that single-band weak-coupling p-wave superconductivity is exhibited in iron-based superconductors.
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20
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Talantsev EF, Strickland NM, Wimbush SC, Brooks J, Pantoja AE, Badcock RA, Storey JG, Tallon JL. The onset of dissipation in high-temperature superconductors: magnetic hysteresis and field dependence. Sci Rep 2018; 8:14463. [PMID: 30262898 PMCID: PMC6160411 DOI: 10.1038/s41598-018-32811-6] [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: 06/13/2018] [Accepted: 09/13/2018] [Indexed: 11/10/2022] Open
Abstract
Recently, we showed that the self-field transport critical current, Ic(sf), of a superconducting wire can be defined in a more fundamental way than the conventional (and arbitrary) electric field criterion, Ec = 1 μV/cm. We defined Ic(sf) as the threshold current, Ic,B, at which the perpendicular component of the local magnetic flux density, B⊥, measured at any point on the surface of a high-temperature superconducting tape abruptly crosses over from a non-linear to a linear dependence with increasing transport current. This effect results from the current distribution across the tape width progressively transitioning from non-uniform to uniform. The completion of this progressive transition was found to be singular. It coincides with the first discernible onset of dissipation and immediately precedes the formation of a measureable electric field. Here, we show that the same Ic,B definition of critical currents applies in the presence of an external applied magnetic field, Ba. In all experimental data presented here Ic,B is found to be significantly (10–30%) lower than Ic,E determined by the common electric field criterion of Ec = 1 µV/cm, and Ec to be up to 50 times lower at Ic,B than at Ic,E.
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Affiliation(s)
- E F Talantsev
- M.N. Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskoy St, Ekaterinburg, 620108, Russia. .,NANOTECH Centre, Ural Federal University, 19 Mira St., Еkaterinburg, 620002, Russia.
| | - N M Strickland
- Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand
| | - S C Wimbush
- Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand.,The MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, P O Box 600, Wellington, 6140, New Zealand
| | - J Brooks
- Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand
| | - A E Pantoja
- Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand
| | - R A Badcock
- Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand
| | - J G Storey
- Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand.,The MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, P O Box 600, Wellington, 6140, New Zealand
| | - J L Tallon
- Robinson Research Institute, Victoria University of Wellington, 69 Gracefield Road, Lower Hutt, 5010, New Zealand.,The MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, P O Box 600, Wellington, 6140, New Zealand
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21
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Paturi P, Malmivirta M, Hynninen T, Huhtinen H. Angle dependent molecular dynamics simulation of flux pinning in YBCO superconductors with artificial pinning sites. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:315902. [PMID: 29957598 DOI: 10.1088/1361-648x/aad02b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A molecular dynamics (MD) simulation to simulate the vortices in superconductors with artificial pinning sites is presented. The simulation reproduces the correct anisotropic behavior in angular dependence of critical current. We also show that the shape of the [Formula: see text] curve depends on the size of the pinning sites and the change from p = 0.5 to [Formula: see text] is due to the breaking of the vortex lattice to individually acting vortices. The results beautifully correspond to experimental data. Furthermore, we found that the size and shape of the c-axis peak observed with columnar pinning sites in [Formula: see text] also depends on the size of the rods, larger pinning sites leading to wider peaks. The results obtained from the MD-simulation are similar to those of the much more computationally intensive Ginzburg-Landau simulations. Furthermore, the MD-simulations can provide insight to the vortex dynamics within the samples.
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Affiliation(s)
- P Paturi
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, Finland
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22
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Qu DX, Teslich NE, Dai Z, Chapline GF, Schenkel T, Durham SR, Dubois J. Onset of a Two-Dimensional Superconducting Phase in a Topological-Insulator-Normal-Metal Bi_{1-x}Sb_{x}/Pt Junction Fabricated by Ion-Beam Techniques. PHYSICAL REVIEW LETTERS 2018; 121:037001. [PMID: 30085782 DOI: 10.1103/physrevlett.121.037001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 05/01/2018] [Indexed: 06/08/2023]
Abstract
Inducing superconductivity in a topological insulator can lead to novel quantum effects. However, experimental approaches to turn a topological insulator into a superconductor are limited. Here, we report on superconductivity in topological insulator Bi_{0.91}Sb_{0.09} induced via focused ion-beam deposition of a Pt thin film. The superconducting phase exhibits a Berezinski-Kosterlitz-Thouless transition, demonstrative of its two-dimensional character. From the in-plane upper critical field measurements, we estimate the superconducting thickness to be ∼17 nm for a 5.5-μm-thick sample. Our results provide evidence that the interface superconductivity could originate from the surface states of Bi_{0.91}Sb_{0.09}.
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Affiliation(s)
- Dong-Xia Qu
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Nick E Teslich
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Zurong Dai
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - George F Chapline
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Thomas Schenkel
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Sean R Durham
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Jonathan Dubois
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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Dimensional crossover and incipient quantum size effects in superconducting niobium nanofilms. Sci Rep 2018; 8:4710. [PMID: 29549273 PMCID: PMC5856833 DOI: 10.1038/s41598-018-22983-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 02/22/2018] [Indexed: 11/18/2022] Open
Abstract
Superconducting and normal state properties of Niobium nanofilms have been systematically investigated as a function of film thickness, on different substrates. The width of the superconducting-to-normal transition for all films is remarkably narrow, confirming their high quality. The superconducting critical current density exhibits a pronounced maximum for thickness around 25 nm, marking the 3D-to-2D crossover. The magnetic penetration depth shows a sizeable enhancement for the thinnest films. Additional amplification effects of the superconducting properties have been obtained with sapphire substrates or squeezing the lateral size of the nanofilms. For thickness close to 20 nm we measured a doubled perpendicular critical magnetic field compared to its large thickness value, indicating shortening of the correlation length and the formation of small Cooper pairs. Our data analysis indicates an exciting interplay between quantum-size and proximity effects together with strong-coupling effects and the importance of disorder in the thinnest films, placing these nanofilms close to the BCS-BEC crossover regime.
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24
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A peak in the critical current for quantum critical superconductors. Nat Commun 2018; 9:434. [PMID: 29382852 PMCID: PMC5789853 DOI: 10.1038/s41467-018-02899-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 01/08/2018] [Indexed: 11/09/2022] Open
Abstract
Generally, studies of the critical current Ic are necessary if superconductors are to be of practical use, because Ic sets the current limit below which there is a zero-resistance state. Here, we report a peak in the pressure dependence of the zero-field Ic, Ic(0), at a hidden quantum critical point (QCP), where a continuous antiferromagnetic transition temperature is suppressed by pressure toward 0 K in CeRhIn5 and 4.4% Sn-doped CeRhIn5. The Ic(0)s of these Ce-based compounds under pressure exhibit a universal temperature dependence, underlining that the peak in zero-field Ic(P) is determined predominantly by critical fluctuations associated with the hidden QCP. The dc conductivity σdc is a minimum at the QCP, showing anti-correlation with Ic(0). These discoveries demonstrate that a quantum critical point hidden inside the superconducting phase in strongly correlated materials can be exposed by the zero-field Ic, therefore providing a direct link between a QCP and unconventional superconductivity.
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25
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Talantsev EF, Pantoja AE, Crump WP, Tallon JL. Current distribution across type II superconducting films: a new vortex-free critical state. Sci Rep 2018; 8:1716. [PMID: 29379094 PMCID: PMC5789066 DOI: 10.1038/s41598-018-20279-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 01/16/2018] [Indexed: 11/30/2022] Open
Abstract
The current distribution across the thickness of a current-carrying rectangular film in the Meissner state was established long ago by the London brothers. The distribution across the width is more complicated but was later shown to be highly non-uniform, diverging at the edges. Accordingly, the standard view for type II superconductors is that vortices enter at the edges and, with increasing current, are driven inwards until they self-annihilate at the centre, causing dissipation. This condition is presumed to define the critical current. However we have shown that, under self-field (no external field), the transport critical current is a London surface current where the surface current density equals the critical field divided by λ, across the entire width. The critical current distribution must therefore be uniform. Here we report studies of the current and field distribution across commercial YBa2Cu3 O7 conductors and confirm the accepted non-uniform distribution at low current but demonstrate a radical crossover to a uniform distribution at critical current. This crossover ends discontinuously at a singularity and calculations quantitatively confirm these results in detail. The onset of self-field dissipation is, unexpectedly, thermodynamic in character and the implied vortex-free critical state seems to require new physics.
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Affiliation(s)
- E F Talantsev
- Robinson Research Institute, Victoria University of Wellington, P.O. Box 33436, Lower Hutt, 5046, New Zealand.
| | - A E Pantoja
- Robinson Research Institute, Victoria University of Wellington, P.O. Box 33436, Lower Hutt, 5046, New Zealand
| | - W P Crump
- Robinson Research Institute, Victoria University of Wellington, P.O. Box 33436, Lower Hutt, 5046, New Zealand
| | - J L Tallon
- Robinson Research Institute, Victoria University of Wellington, P.O. Box 33436, Lower Hutt, 5046, New Zealand. .,MacDiarmid Institute for Advanced Materials and Nanotechnology, P.O. Box 33436, Lower Hutt, 5046, New Zealand.
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26
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Talantsev EF, Crump WP, Tallon JL. Universal scaling of the self-field critical current in superconductors: from sub-nanometre to millimetre size. Sci Rep 2017; 7:10010. [PMID: 28855601 PMCID: PMC5577115 DOI: 10.1038/s41598-017-10226-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 08/08/2017] [Indexed: 11/08/2022] Open
Abstract
Universal scaling behaviour in superconductors has significantly elucidated fluctuation and phase transition phenomena in these materials. However, universal behaviour for the most practical property, the critical current, was not contemplated because prevailing models invoke nucleation and migration of flux vortices. Such migration depends critically on pinning, and the detailed microstructure naturally differs from one material to another, even within a single material. Through microstructural engineering there have been ongoing improvements in the field-dependent critical current, thus illustrating its non-universal behaviour. But here we demonstrate the universal size scaling of the self-field critical current for any superconductor, of any symmetry, geometry or band multiplicity. Key to our analysis is the huge range of sample dimensions, from single-atomic-layer to mm-scale. These have widely variable microstructure with transition temperatures ranging from 1.2 K to the current record, 203 K. In all cases the critical current is governed by a fundamental surface current density limit given by the relevant critical field divided by the penetration depth.
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Affiliation(s)
- E F Talantsev
- Robinson Research Institute, Victoria University of Wellington, P.O. Box 33436, Lower Hutt, 5046, New Zealand.
| | - W P Crump
- Robinson Research Institute, Victoria University of Wellington, P.O. Box 33436, Lower Hutt, 5046, New Zealand
| | - J L Tallon
- Robinson Research Institute, Victoria University of Wellington, P.O. Box 33436, Lower Hutt, 5046, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, P.O. Box 33436, Lower Hutt, 5046, New Zealand
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27
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Nappi C, Camerlingo C, Enrico E, Bellingeri E, Braccini V, Ferdeghini C, Sarnelli E. Current Induced Resistive State in Fe(Se,Te) Superconducting Nanostrips. Sci Rep 2017; 7:4115. [PMID: 28646157 PMCID: PMC5482902 DOI: 10.1038/s41598-017-04425-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 05/16/2017] [Indexed: 11/21/2022] Open
Abstract
We study the current-voltage characteristics of Fe(Se,Te) thin films deposited on CaF2 substrates in form of nanostrips (width w ~ λ, λ the London penetration length). In view of a possible application of these materials to superconductive electronics and micro-electronics we focus on transport properties in small magnetic field, the one generated by the bias current. From the characteristics taken at different temperatures we derive estimates for the pinning potential U and the pinning potential range δ for the magnetic flux lines (vortices). Since the sample lines are very narrow, the classical creep flow model provides a sufficiently accurate interpretation of the data only when the attractive interaction between magnetic flux lines of opposite sign is taken into account. The observed voltages and the induced depression of the critical current of the nanostrips are compatible with the presence of a low number ([Formula: see text]) magnetic field lines at the equilibrium, a strongly inhomogeneous current density distribution at the two ends of the strips and a reduced Bean Livingston barrier. In particular, we argue that the sharp corners defining the bridge geometry represent points of easy magnetic flux lines injection. The results are relevant for creep flow analysis in superconducting Fe(Se,Te) nanostrips.
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Affiliation(s)
- Ciro Nappi
- CNR-SPIN, Sede secondaria di Napoli, I-80078, Pozzuoli, Napoli (NA), Italy.
| | - Carlo Camerlingo
- CNR-SPIN, Sede secondaria di Napoli, I-80078, Pozzuoli, Napoli (NA), Italy
| | - Emanuele Enrico
- INRIM, Istituto Nazionale di Ricerca Metrologica, I-10135, Torino, Italy
| | | | | | | | - Ettore Sarnelli
- CNR-SPIN, Sede secondaria di Napoli, I-80078, Pozzuoli, Napoli (NA), Italy.
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