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Hafner D, Dressel M, Scheffler M. Surface-resistance measurements using superconducting stripline resonators. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:014702. [PMID: 24517793 DOI: 10.1063/1.4856475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present a method to measure the absolute surface resistance of conductive samples at a set of GHz frequencies with superconducting lead stripline resonators at temperatures 1-6 K. The stripline structure can easily be applied for bulk samples and allows direct calculation of the surface resistance without the requirement of additional calibration measurements or sample reference points. We further describe a correction method to reduce experimental background on high-Q resonance modes by exploiting TEM-properties of the external cabling. We then show applications of this method to the reference materials gold, tantalum, and tin, which include the anomalous skin effect and conventional superconductivity. Furthermore, we extract the complex optical conductivity for an all-lead stripline resonator to find a coherence peak and the superconducting gap of lead.
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Affiliation(s)
- Daniel Hafner
- 1. Physikalisches Institut, Universität Stuttgart, D-70550 Stuttgart, Germany
| | - Martin Dressel
- 1. Physikalisches Institut, Universität Stuttgart, D-70550 Stuttgart, Germany
| | - Marc Scheffler
- 1. Physikalisches Institut, Universität Stuttgart, D-70550 Stuttgart, Germany
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Voo KK. Order and excitation in partially Gutzwiller projected t-t'-t"-J-U models. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:495602. [PMID: 22101308 DOI: 10.1088/0953-8984/23/49/495602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Extended t-t'-t"-J-U models in which the second-nearest-neighbor hopping (t') and third-nearest-neighbor hopping (t") are included are studied using renormalized mean field theory. The models are meant to be low-energy effective models for the Hubbard models, and hence the Heisenberg exchange integral J and Hubbard repulsion U are related by J = 4t(2)/U. The trial wavefunctions for the ground states are partially Gutzwiller projected Hartree-Fock states. The Gutzwiller projection is implemented by means of a Gutzwiller approximation, and the site double occupancy d is taken as a variational parameter. It is found that a large |t'/t| narrows the band filling range that sustains antiferromagnetism (AFM) in the ground state, enhances the d-wave singlet superconductivity (dSC) in hole overdoped systems, but suppresses the dSC in electron overdoped systems. For a system that has large |t'/t| and |t"/t'|, the superconductivity (SC) at the onset of AFM in hole doped band filling is strongly suppressed. On the excitation occurring, when an electron doped system simultaneously contains SC and AFM, the system is found to have a nodeless gap at the Fermi level. Finally, the result of this study is related to experiments on the superconducting cuprates.
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Affiliation(s)
- Khee-Kyun Voo
- Department of Communication Engineering, Oriental Institute of Technology, Banqiao Area, New Taipei City 22061, Taiwan.
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Voo KK. Antiferromagnetism and superconductivity in an electron-doped two-dimensional t-U-V model. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:275702. [PMID: 21399265 DOI: 10.1088/0953-8984/22/27/275702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The antiferromagnetism (AFM) and superconductivity (SC) in a t-U-V model for an electron-doped two-dimensional square lattice has been investigated with a mean field approximation. Mean field solutions with 2 × 2 unit structures have been sought. The major merit in this study is that all possible superconducting pairings having 2 × 2 unit structures are considered. It has been found that the spin states and orbitals in the superconducting pairing depend on the band filling, and AFM induces a staggered triplet pairing in a system with a d(x(2)-y(2)) orbital singlet SC (dSC). The ratio of the magnitude of the triplet pairing to the magnitude of the singlet pairing has been found to grow monotonically with the antiferromagnetic moment. However, this additional triplet may not have observable effects in many frequently carried out measurements. We have focused on band fillings higher than half-filled. Fundamental quantities including the density of states, local density of states, and single particle spectral weight have been discussed. This study may be related to the electron-doped high-temperature superconducting cuprates, where there have been experimental observations of AFM and SC coexisting, and the nature of the superconducting pairing has been controversial.
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Affiliation(s)
- Khee-Kyun Voo
- Department of Communication Engineering, Oriental Institute of Technology, Banqiao City, Taipei County 22061, Taiwan.
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Das T, Markiewicz RS, Bansil A. Nodeless d-wave superconducting pairing due to residual antiferromagnetism in underdoped Pr2-xCexCuO4-delta. PHYSICAL REVIEW LETTERS 2007; 98:197004. [PMID: 17677653 DOI: 10.1103/physrevlett.98.197004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Indexed: 05/16/2023]
Abstract
We investigate the doping dependence of the penetration depth versus temperature in electron-doped Pr(2-x)Ce(x)CuO(4-delta) using a model which assumes the uniform coexistence of (mean-field) antiferromagnetism and superconductivity. Despite the presence of a d(x2-y2) pairing gap in the underlying spectrum, we find nodeless behavior of the low-T penetration depth in the underdoped case, in accord with experimental results. As doping increases, a linear-in-T behavior of the penetration depth, characteristic of d-wave pairing, emerges as the lower magnetic band crosses the Fermi level and creates a nodal Fermi surface pocket.
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Affiliation(s)
- Tanmoy Das
- Physics Department, Northeastern University, Boston, MA 02115, USA
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Darminto D, Smilde HJH, Leca V, Blank DHA, Rogalla H, Hilgenkamp H. Phase-sensitive order parameter symmetry test experiments utilizing Nd(2-x)Ce(x)CuO(4-y)/Nb zigzag junctions. PHYSICAL REVIEW LETTERS 2005; 94:167001. [PMID: 15907157 DOI: 10.1103/physrevlett.94.167001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2004] [Indexed: 05/02/2023]
Abstract
Phase-sensitive order parameter symmetry test experiments are presented on the electron-doped high-T(c) cuprate Nd(2-x)Ce(x)CuO(4-y). These experiments have been conducted using zigzag-shaped thin film Josephson structures, in which the Nd(2-x)Ce(x)CuO(4-y) is connected to the low-T(c) superconductor Nb via an Au barrier layer. For the optimally doped as well as for the overdoped Nd(2-x)Ce(x)CuO(4-y), a clear predominant d(x2-y2)-wave behavior is observed at T=4.2 K. Both compounds were also investigated at T=1.6 K, presenting no indications for a change to a predominant s-wave symmetry with decreasing temperature.
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Sonier JE, Poon KF, Luke GM, Kyriakou P, Miller RI, Liang R, Wiebe CR, Fournier P, Greene RL. Superconductivity and field-induced magnetism in Pr2-xCexCuO4 single crystals. PHYSICAL REVIEW LETTERS 2003; 91:147002. [PMID: 14611547 DOI: 10.1103/physrevlett.91.147002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2003] [Indexed: 05/24/2023]
Abstract
We report muon-spin rotation and relaxation (muSR) measurements on single crystals of the electron-doped high-T(c) superconductor Pr2-xCexCuO4. In a zero external magnetic field, superconductivity is found to coexist with dilute Cu spins that are static on the muSR time scale. In an applied field, we observe a mu(+)-Knight shift that is primarily due to the magnetic moment induced on the Pr ions. Below the superconducting transition temperature T(c), an additional source of local magnetic field appears throughout the volume of the sample. This finding is shown to be consistent with field-induced antiferromagnetic ordering of the Cu spins. Measurements of the temperature dependence of the in-plane magnetic penetration depth lambda(ab) in the vortex state are also presented.
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Affiliation(s)
- J E Sonier
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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Biswas A, Fournier P, Qazilbash MM, Smolyaninova VN, Balci H, Greene RL. Evidence of a d- to s-wave pairing symmetry transition in the electron-doped cuprate superconductor Pr(2-x)CexCuO4. PHYSICAL REVIEW LETTERS 2002; 88:207004. [PMID: 12005593 DOI: 10.1103/physrevlett.88.207004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2001] [Indexed: 05/23/2023]
Abstract
We present point contact spectroscopy (PCS) data for junctions between a normal metal and the electron-doped cuprate superconductor Pr(2-x)CexCuO4 (PCCO). For the underdoped compositions of this cuprate ( x approximately 0.13) we observe a peak in the conductance-voltage characteristics of the point contact junctions. The shape and magnitude of this peak suggest the presence of Andreev bound states at the surface of underdoped PCCO which is evidence for a d-wave pairing symmetry. For overdoped PCCO ( x approximately 0.17) the PCS data do not show any evidence of Andreev bound states at the surface suggesting an s-wave pairing symmetry.
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Affiliation(s)
- Amlan Biswas
- Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, Maryland 20742
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Sato T, Kamiyama T, Takahashi T, Kurahashi K, Yamada K. Observation of d(x2-y2)-like superconducting gap in an electron-doped high-temperature superconductor. Science 2001; 291:1517-9. [PMID: 11222851 DOI: 10.1126/science.1058021] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
High-resolution angle-resolved photoemission spectroscopy of the electron-doped high-temperature superconductor Nd(2-x)Ce(x)CuO4 (x = 0.15, transition temperature T(c) = 22 K) has found the quasiparticle signature as well as the anisotropic d(x2-y2)-like superconducting gap. The spectral line shape at the superconducting state shows a strong anisotropic nature of the many-body interaction. The result suggests that the electron-hole symmetry is present in the high-temperature superconductors.
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Affiliation(s)
- T Sato
- Department of Physics, Tohoku University, Sendai 980-8578, Japan., Institute for Chemical Research, Kyoto University, Uji 611-0011, Japan
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Kokales JD, Fournier P, Mercaldo LV, Talanov VV, Greene RL, Anlage SM. Microwave electrodynamics of electron-doped cuprate superconductors. PHYSICAL REVIEW LETTERS 2000; 85:3696-3699. [PMID: 11030984 DOI: 10.1103/physrevlett.85.3696] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2000] [Indexed: 05/23/2023]
Abstract
We report microwave cavity perturbation measurements of the temperature dependence of the penetration depth, lambda(T), and conductivity, sigma(T) of Pr(2-x)Ce(x)CuO(4-delta) (PCCO) crystals, as well as parallel-plate resonator measurements of lambda(T) in PCCO thin films. Penetration depth measurements are also presented for a Nd(2-x)Ce(x)CuO(4-delta) (NCCO) crystal. We find that Deltalambda(T) has a power-law behavior for T<T(c)/3, and conclude that the electron-doped cuprate superconductors have nodes in the superconducting gap. Furthermore, using the surface impedance, we have derived the real part of the conductivity, sigma(1)(T), below T(c) and found a behavior similar to that observed in hole-doped cuprates.
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Affiliation(s)
- JD Kokales
- Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
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Tsuei CC, Kirtley JR. Phase-sensitive evidence for d-wave pairing symmetry in electron-doped cuprate superconductors. PHYSICAL REVIEW LETTERS 2000; 85:182-185. [PMID: 10991189 DOI: 10.1103/physrevlett.85.182] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2000] [Indexed: 05/23/2023]
Abstract
We present phase-sensitive evidence that the electron-doped cuprates Nd(1.85)Ce(0.15)CuO(4-y) (NCCO) and Pr(1.85)Ce(0.15)CuO(4-y) (PCCO) have d-wave pairing symmetry. This evidence was obtained by observing the half-flux quantum effect, using a scanning SQUID microscope, in c-axis-oriented films of NCCO or PCCO epitaxially grown on tricrystal [100] SrTiO3 substrates designed to be frustrated for a d(x(2)-y(2)) order parameter. Samples with two other configurations, designed to be unfrustrated for a d-wave superconductor, do not show the half-flux quantum effect.
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Affiliation(s)
- CC Tsuei
- IBM T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598, USA
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Karpinska K, Cieplak MZ, Guha S, Malinowski A, Skoskiewicz T, Plesiewicz W, Berkowski M, Boyce B, Lemberger TR, Lindenfeld P. Metallic nonsuperconducting phase and D-wave superconductivity in Zn-substituted La1.85Sr0.15CuO4. PHYSICAL REVIEW LETTERS 2000; 84:155-158. [PMID: 11015858 DOI: 10.1103/physrevlett.84.155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/1999] [Indexed: 05/23/2023]
Abstract
Measurements of the resistivity, magnetoresistance, and penetration depth were made on films of La1.85Sr0.15CuO4, with up to 12 at. % of Zn substituted for the Cu. The results show that the quadratic temperature dependence of the inverse square of the penetration depth, indicative of d-wave superconductivity, is not affected by doping. The suppression of superconductivity leads to a metallic nonsuperconducting phase, as expected for a pairing mechanism related to spin fluctuations. The metal-insulator transition occurs in the vicinity of k(F)l approximately 1, and appears to be disorder driven, with the carrier concentration unaffected by doping.
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Affiliation(s)
- K Karpinska
- Institute of Physics, Polish Academy of Sciences, 02 668 Warsaw, Poland
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Cooper JR. Power-law dependence of the ab-plane penetration depth in Nd1.85Ce0.15CuO4-y. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:R3753-R3755. [PMID: 9986364 DOI: 10.1103/physrevb.54.r3753] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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13
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Anlage SM, Wu DH, Mao J, Mao SN, Xi XX, Venkatesan T, Peng JL, Greene RL. Electrodynamics of Nd1.85Ce0.15CuO4: Comparison with Nb and YBa2Cu3O7- delta. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:523-535. [PMID: 9974571 DOI: 10.1103/physrevb.50.523] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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