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Volovik, G. E.; Pudalov, V. M.

doi:10.1134/s002136401624005x

Cited by 54 publications

(91 citation statements)

References 52 publications

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“…For a d-wave superconductor Volovik predicted an H 1/2 dependence associated with extended quasiparticle states near line nodes. 25 This effect was first observed by Moler et al 26 in a cuprate superconductor. It has been suggested that this H 1/2 dependence is modified to HlnH at low fields in a dirty superconductor.…”

Section: Discussionmentioning

confidence: 75%

Specific Heat of Ba_0.59K_0.41Fe₂As₂, an Fe-Pnictide Superconductor with T_c = 36.9 K, and a New Method for Identifying the Electron Contribution

et al. 2015

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We report measurements of the specific heat of Ba 0.59 K 0.41 Fe 2 As 2 , an Fe-pnictide superconductor with T c = 36.9 K, for which there are suggestions of an unusual electron pairing mechanism. We use a new method of analysis of the data to derive the parameters characteristic of the electron contribution. It is based on comparisons of α-model expressions for the electron contribution with the total specific heat, which give the electron contribution directly. It obviates the need in the conventional analyses for an independent, necessarily approximate, determination of the lattice contribution, which is subtracted from the total specific heat to obtain the electron contribution. It eliminates the uncertainties and errors in the electron contribution that follow from the approximations in the determination of the lattice contribution. Our values of the parameters characteristic of the electron contribution differ significantly from those obtained in conventional analyses of specific-heat data for five similar holedoped BaFe 2 As 2 superconductors, which also differ significantly among themselves. For Ba 0.59 K 0.41 Fe 2 As 2 the electron density of states is comprised of contributions from two electron bands with superconducting-state energy gaps that differ by a factor 3.8, with 77% coming from the band with the larger gap. The variation of the specific heat with magnetic field is consistent with extended s-wave pairing, one of the theoretical predictions. The relation between the densities of states and the energy gaps in the two bands is not consistent with a theoretical model based on interband interactions alone. Comparison of the normal-state density of states with band-structure calculations shows an extraordinarily large effective mass 2 enhancement, for which there is no precedent in similar materials and no theoretical explanation.

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Section: Discussionmentioning

confidence: 75%

Specific Heat of Ba_0.59K_0.41Fe₂As₂, an Fe-Pnictide Superconductor with T_c = 36.9 K, and a New Method for Identifying the Electron Contribution

et al. 2015

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“…Here we show that the physical mechanism, responsible for above non-BCS behavior of overdoped LSCO, stems from the topological fermion condensation quantum phase transition (FCQPT) accompanied by so-called fermion condensation (FC) phenomenon generating flat bands [8][9][10][11][12][13][14] . We note that flat bands and extended saddle point singularity play important role in the theory of HTSC, see e.g.…”

Section: Introductionmentioning

confidence: 99%

“…These observations representing the intrinsic LSCO properties provide unique opportunities for checking and expanding our understanding of the physical mechanisms responsible for high-T c superconductivity. We note, that that knowing the responsible mechanism can open avenue for chemical preparation of high-T c materials with T c as high as room temperature [8][9][10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

The influence of topological phase transition on the superfluid density of overdoped copper oxides

Shaginyan

Stephanovich

Msezane

et al. 2017

Phys. Chem. Chem. Phys.

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We show that a topological quantum phase transition, generating flat bands and altering Fermi surface topology, is a primary reason for the exotic behavior of the overdoped high-temperature superconductors represented by La2−xSrxCuO4, whose superconductivity features differ from what is described by the classical Bardeen-Cooper-Schrieffer theory [J.I. Boẑović, X. He, J. Wu, and A. T. Bollinger, Nature 536, 309 (2016)]. We demonstrate that 1) at temperature T = 0, the superfluid density ns turns out to be considerably smaller than the total electron density; 2) the critical temperature Tc is controlled by ns rather than by doping, and is a linear function of the ns; 3) at T > Tc the resistivity ρ(T ) varies linearly with temperature, ρ(T ) ∝ αT , where α diminishes with Tc → 0, while in the normal overdoped (non superconducting) region with Tc = 0, the resistivity becomes ρ(T ) ∝ T 2 . The theoretical results presented are in good agreement with recent experimental observations, closing the colossal gap between these empirical findings and Bardeen-Cooper-Schrieffer-like theories.

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“…[36], and for x = 7 from [37] (dash-dot line), and introduce each one in Eq. (20) to perform the integrals numerically. The difference between the first two curves and the third one is small in the 20 K < T < 80 K interval and for T > 80 K it widens progressively.…”

Section: A Lattice Specific Heatmentioning

confidence: 99%

“…[16] and references therein), and its superconducting counterpart that evolves as γ 0 when the temperature approaches zero. Secondly, there is a quadratic αT 2 term for zero magnetic field [17][18][19] below T c (not exhibited in conventional superconductors), which changes to a H 1/2 T component in the presence of an external magnetic field [20] H, attributable to the superconducting part of the electronic specific heat C es . The reported values for this two constants depend strongly on the conditions of each experiment [17] and on the theoretical method used to relate the different parts of the total specific heat.…”

Section: Introductionmentioning

confidence: 99%

Specific heat of underdoped cuprate superconductors from a phenomenological layered Boson–Fermion model

Salas

Fortes

Solís

et al. 2016

Physica C: Superconductivity and its Applications

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We adapt the Boson-Fermion superconductivity model to include layered systems such as underdoped cuprate superconductors. These systems are represented by an infinite layered structure containing a mixture of paired and unpaired fermions. The former, which stand for the superconducting carriers, are considered as noninteracting zero spin composite-bosons with a linear energymomentum dispersion relation in the CuO2 planes where superconduction is predominant, coexisting with the unpaired fermions in a pattern of stacked slabs. The inter-slab, penetrable, infinite planes are generated by a Dirac comb potential, while paired and unpaired electrons (or holes) are free to move parallel to the planes. Composite-bosons condense at a critical temperature at which they exhibit a jump in their specific heat. These two values are assumed to be equal to the superconducting critical temperature Tc and the specific heat jump reported for YBa2Cu3O6.80 to fix our model parameters namely, the plane impenetrability and the fraction of superconducting charge carriers. We then calculate the isochoric and isobaric electronic specific heats for temperatures lower than Tc of both, the composite-bosons and the unpaired fermions, which matches recent experimental curves. From the latter, we extract the linear coefficient (γn) at Tc, as well as the quadratic (αT 2 ) term for low temperatures. We also calculate the lattice specific heat from the ARPES phonon spectrum, and add it to the electronic part, reproducing the experimental total specific heat at and below Tc within a 5% error range, from which the cubic (ßT 3 ) term for low temperatures is obtained. In addition, we show that this model reproduces the cuprates mass anisotropies.

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Graphite on graphite

Cited by 54 publications

References 52 publications

Specific Heat of Ba_0.59K_0.41Fe₂As₂, an Fe-Pnictide Superconductor with T_c = 36.9 K, and a New Method for Identifying the Electron Contribution

Specific Heat of Ba_0.59K_0.41Fe₂As₂, an Fe-Pnictide Superconductor with T_c = 36.9 K, and a New Method for Identifying the Electron Contribution

The influence of topological phase transition on the superfluid density of overdoped copper oxides

Specific heat of underdoped cuprate superconductors from a phenomenological layered Boson–Fermion model

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Graphite on graphite

Cited by 54 publications

References 52 publications

Specific Heat of Ba0.59K0.41Fe2As2, an Fe-Pnictide Superconductor with Tc = 36.9 K, and a New Method for Identifying the Electron Contribution

Specific Heat of Ba0.59K0.41Fe2As2, an Fe-Pnictide Superconductor with Tc = 36.9 K, and a New Method for Identifying the Electron Contribution

The influence of topological phase transition on the superfluid density of overdoped copper oxides

Specific heat of underdoped cuprate superconductors from a phenomenological layered Boson–Fermion model

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Product

Resources

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Specific Heat of Ba_0.59K_0.41Fe₂As₂, an Fe-Pnictide Superconductor with T_c = 36.9 K, and a New Method for Identifying the Electron Contribution

Specific Heat of Ba_0.59K_0.41Fe₂As₂, an Fe-Pnictide Superconductor with T_c = 36.9 K, and a New Method for Identifying the Electron Contribution