The disordered Bose condensate in two dimensions: application to high-Tc superconductors

Gold, A.

doi:10.1016/0921-4534(92)90710-t

Cited by 20 publications

(17 citation statements)

References 35 publications

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“…We believe the model considered to be of importance on its own right, as it exhibits a rather non-trivial behaviour and allows a fully analytic treatment. The comparison of our results with those, obtained for the other model of the disordered Bose systems numerically and semi-analytically within the same theoretical framework 6,7 , leads to the conclusion, that in both cases the phase diagram and the optical spectra are essentially the same and are fairly weakly sensitive to the character of the interparticle interaction, the impurity potential and the dimensionality of the systems. Thus, we hope the present study may shed light on the behaviour of more realistic models, that do not permit such an elementary analysis.…”

Section: Discussionsupporting

confidence: 65%

Superfluid–Bose-glass transition in two dimensions at T = 0: Analytic solution of a mode-coupling toy model

Zenkov¹

2005

Europhys. Lett.

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Analytic expression for the memory function and the optical conductivity of the two-dimensional Bose gas with logarithmic interaction at T = 0 in presence of point-like impurities is obtained within the mode-coupling approximation. Depending on the value of a dimensionless combination of the model parameters proportional to the strength of the impurity potential, two different phases are distinguished, viz. the disordered superfluid and insulator (Bose glass), separated by an intermediate (quasi)metal state.

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Section: Discussionsupporting

confidence: 65%

Superfluid–Bose-glass transition in two dimensions at T = 0: Analytic solution of a mode-coupling toy model

Zenkov¹

2005

Europhys. Lett.

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“…There are the following experimental facts also: (i) the small value of the entropy (or the large single particle condensate fraction n B0 in our context) observed in HTSC at T < T c 31 in comparison with its value expected for an ideal 3D-BG; (ii) the kink-like increase of the entropy 34 ; (iii) the SF density change n S (t) = n S (0)[1 − (T /T c ) 4 ] (with n S0 = 4n S (0) which corresponds to our n B0 (0) = 0.25 and γ B 1.4 at ξ BA /T BEC = 20) for HTSC 192,206 and HFSC 207 ; (iv) the crossing of the magnetization (including specific heat) curves at a characteristic temperature T * near T c (these anomalies of the magnetization and specific heat perhaps occur in the range T * B < T * < T c and are caused by the decreasing of T * B and increasing of T c (= T B ) under magnetic fields just as in the PME (see Fig. 1 in Ref.…”

Section: Other Confirmationsmentioning

confidence: 98%

The Microscopic Theory of Superfluidity and Superconductivity Driven by Single Particle and Pair Condensation of Attracting Bosons

Dzhumanov

1998

Int. J. Mod. Phys. B

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A original microscopic theory of superfluidity and superconductivity driven by the single particle (SPC) and pair condensation (PC) of attracting bosons both in Fermi and in Bose systems is developed. This theory (as distinct from the existing theories) for Fermi systems contains two order parameters ∆ F and ∆ B characterizing the attracting fermion pairs and boson pairs, respectively. In such systems superconducting (SC) phase transition is accompanied, as a rule, by the formation of k-space composite bosons (e.g. Cooper pairs and bipolarons) with their subsequent transition to the superfluid (SF) state by attractive SPC and PC. A novel Fermi-liquid and SF Bose-liquid theories are elaborated for description this two-stage Fermi-Bose-liquid (FBL) scenario of SC (or SF) transition. The crossover from k-to real (r)-space pairing regime for BCS-like coupling constants γ F 0.7 − 0.9 and the irrelevance of r-space pairs to the superconductivity are shown. The developed SF Bose-liquid theory predicts the first-order phase transition SPC ↔ PC of attracting 3d-bosons with the kink-like behaviors of all SC (SF) parameters near T = T * B < Tc in accordance with the observations in 4 He, 3 He and superconductors. It is argued that the coexistence of the order parameters ∆ F and ∆ B leads to the superconductivity by two FBL scenarios. One of these scenarios is realized in the so-called fermion (type I, II and III) superconductors (FSC) (where formation of k-space composite bosons and their condensation occur at the same temperature) and the other in the boson (type II and III) superconductors (BSC) (where BCS-like pairing take place in the normal state with manifesting of the second-order phase transition and opening of the pseudogap at T = T F > Tc). There the gapless superfluidity (superconductivity) is caused by the gapless excitation spectrum of bosons at T ≤ T * B and not by the presence of point or line nodes of the BCS-like gap ∆ F assumed in some s-, pand d-pairing models. The 3D-and 2D-insulator-metal-superconductor phase diagrams are presented. The necessary and sufficient microscopic criterions for superfluidity is formulated. The theory proposed are in close agreement with the observations in 4 He, 3 He, superconductors, nuclear and neutron star matter, cosmology, etc.

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“…To our opinion, the approach considered in Ref. 10 and in the present work deserves attention in connexion with the far-IR features in optical conductivity spectra of underdoped HTSC's, that are presumably related to the stripe excitations 11 or Wigner crystal dynamics 12 . In particular, the in-plane optical conductivity of La 2−x Sr x CuO 4 (0 < x < 0.26) is found to display strong resonant structure around ∼ 100 cm −1 , that consists of a main peak and a series of less pronounced peaks at higher frequencies 11 .…”

Section: Discussionmentioning

confidence: 72%

Optical conductivity of Bose droplets in quenched disorder at : The effects of structure factor

Zenkov¹

2007

Physica B: Condensed Matter

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The optical response of a system of two-dimensional Bose condensate droplets with an internal charge structure interacting with impurities is considered within the mode-coupling theory. It is found, that the glass transition in the system of droplets occurs at much stronger disorder as compared to the case of stuctureless point particles. The optical conductivity of the system is found to exhibit a complex oscillating structure, intimately related to the charge distribution within the droplets. The application of the model to the problem of the far IR optical conductivity of doped cuprates La2−xSrxCuO4 (x < 0.26) is discussed.

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The disordered Bose condensate in two dimensions: application to high-Tc superconductors

Cited by 20 publications

References 35 publications

Superfluid–Bose-glass transition in two dimensions at T = 0: Analytic solution of a mode-coupling toy model

Superfluid–Bose-glass transition in two dimensions at T = 0: Analytic solution of a mode-coupling toy model

The Microscopic Theory of Superfluidity and Superconductivity Driven by Single Particle and Pair Condensation of Attracting Bosons

Optical conductivity of Bose droplets in quenched disorder at : The effects of structure factor

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