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

Shaginyan, V. R.; Stephanovich, V. A.; Msezane, A. Z.; Japaridze, G. S.; Попов, К. Г.

doi:10.1039/c7cp02720f

Cited by 15 publications

(34 citation statements)

References 33 publications

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“…On the contrary to [30] it was shown in recent work [33] that the linear dependence of T c on the number of Cooper pairs observed in [28] in the overdoped La 2−x Sr x Cu 2 O crystals can be described by BCS model for plasmon mechanism of SC. It seems nevertheless that the special case considered in [30] can not explain the general character of results obtained in [28].…”

Section: Comparison With the Experimentsmentioning

confidence: 71%

Superconducting properties of a nonideal bipolaron gas

Лахно

2019

Physica C: Superconductivity and its Applications

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The properties of a Bose gas of translation-invariant (TI) bipolarons analogous to Cooper pairs are considered. As in the BCS theory, the description of a TI-bipolaron gas is based on the electron-phonon interaction and FroehlichHamiltonian. As distinct from the BCS theory, when the correlation length greatly exceeds the mean distance between the pairs, here we deal with the opposite case when the correlation length is much less than the distance between the pairs. We calculate the critical temperature of the transition of a TI-bipolaron Bose-gas into the superconducting state, its energy, heat capacity and heat of the transition. The results obtained are used to explain the experiments on high-temperature superconductors. Possible ways of raising the critical temperature of high-temperature superconductors are discussed.

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Section: Comparison With the Experimentsmentioning

confidence: 71%

Superconducting properties of a nonideal bipolaron gas

Лахно

2019

Physica C: Superconductivity and its Applications

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“…On the other hand, thermal fluctuations destroy LFL behavior and generate NFL features related to the FC state. In fact, at T = 0 the FC state is represented by the superconducting state with the superconducting gap ∆ = 0, while the superconducting order parameter κ = n(p)(1 − n(p)) is finite in the region (p i − p f ) [16,31,46], for in the region n(p) < 1.…”

Section: Thermodynamic Propertiesmentioning

confidence: 99%

Thermodynamic, Dynamic, and Transport Properties of Quantum Spin Liquid in Herbertsmithite from an Experimental and Theoretical Point of View

et al. 2019

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In our review we focus on the quantum spin liquid (QSL), defining the thermodynamic, transport and relaxation properties of geometrically frustrated magnet (insulators) represented by herbertsmithite ZnCu3(OH)6Cl2. QSL is a quantum state of matter having neither magnetic order nor gapped excitations even at zero temperature. QSL along with heavy fermion metals can form a new state of matter induced by the topological fermion condensation quantum phase transition. The observation of QSL in actual materials such as herbertsmithite is of fundamental significance both theoretically and technologically, as it could open a path to creation of topologically protected states for quantum information processing and quantum computation. It is therefore of great importance to establish the presence of a gapless QSL state in one of the most prospective material herbertsmithite. In this respect, interpretation of current theoretical and experimental studies of herbertsmithite are controversial in their implications. Based on published experimental data augmented by our theoretical analysis, we present evidence for the the existence of a QSL in the geometrically frustrated insulator herbertsmithite ZnCu3(OH)6Cl2, providing a strategy for unambiguous identification of such a state in other materials. To clarify the nature of QSL in herbertsmithite, we recommend measurements of heat transport, low-energy inelastic neutron scattering, and optical conductivity σ in ZnCu3(OH)6Cl2 crystals subject to an external magnetic field at low temperatures. Our analysis of the behavior of σ in herbertsmithite justifies this set of measurements, which can provide conclusive experimental demonstration of the nature of its spinon-composed quantum spin liquid. Theoretical study of the optical conductivity of herbertsmithite allows us to expose the physical mechanisms responsible for its temperature and magnetic-field dependence. We also suggest that artificially or spontaneous introducing inhomogeneity at nanoscale into ZnCu3(OH)6Cl2 can both stabilize its QSL and simplify its chemical preparation, and can provide for tests that elucidate the role of impurities. We make predictions of the results of specified measurements related to the dynamical, thermodynamic and transport properties in the case of a gapless QSL.

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“…Among them is the Leggett theorem violation with n s << n t [16]. Indeed, in this case the Leggett theorem does not apply since the T-and C-invariance are violated in the systems with FC [2,3,17].…”

Section: Introductionmentioning

confidence: 99%

Flat bands and strongly correlated Fermi systems

et al. 2019

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Some materials can have the dispersionless parts in their electronic spectra. These parts are usually called flat bands and generate the corps of unusual physical properties of such materials. These flat bands are induced by the condensation of fermionic quasiparticles [1-3], being very similar to the Bose condensation. The difference is that fermions to condense, the Fermi surface should change its topology [1-4], leading to violation of time-reversal (T) and particle-hole (C) symmetries. Thus, the famous Landau theory of Fermi liquids does not work for the systems with fermion condensate (FC) so that several experimentally observable anomalies have not been explained so far.Here we use FC approach to explain recent observations of the asymmetric tunneling conductivity in heavy-fermion compounds and graphene [5][6][7] and its restoration in magnetic fields, as well as the violation of Leggett theorem [8,9], recently observed experimentally [10,11] in overdoped cuprates, and recent observation of the challenging universal scaling connecting linear-T -dependent resistivity to the superconducting superfluid density [12].

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

Cited by 15 publications

References 33 publications

Superconducting properties of a nonideal bipolaron gas

Superconducting properties of a nonideal bipolaron gas

Thermodynamic, Dynamic, and Transport Properties of Quantum Spin Liquid in Herbertsmithite from an Experimental and Theoretical Point of View

Flat bands and strongly correlated Fermi systems

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