The Two Energy Scales of Tunneling Spectra of Cuprate Superconductors

Mello, E. V. L. de; Kasal, R.B.

doi:10.1007/s10948-010-1093-1

Cited by 6 publications

(15 citation statements)

References 18 publications

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“…The subject of phase separ Recent scanning tunneling microscopy (STM) studies on Bi2212 reveal spatial variations of the electronic gap amplitude on a nanometer length scale even on overdoped compounds [11][12][13]. The local density of states (LDOS) measured in these STM experiments [11][12][13] has two different forms that are possibly associated with a segregation into metallic and insulator nanoscopic regions [14]. Consequently the electronic phase separation in cuprates has been the subject of many articles [15][16][17][18][19][20][21][22] and many books [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Random resistivity network calculations for cuprate superconductors with an electronic phase separation transition

Pinheiro¹,

Mello²

2012

Physica A: Statistical Mechanics and its Applications

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The resistivity as function of temperature of high temperature superconductors is very unusual and despite its importance lacks an unified theoretical explanation. It is linear with the temperature for overdoped compounds but it falls more quickly as the doping level decreases. The resistivity of underdoped cuprates increases as an insulator below a characteristic temperature where it shows a minimum. We show that this overall behavior can be explained by calculations using an electronic phase segregation into two main component phases with low and high electronic densities. The total resistence is calculated by the various contributions through several random picking processes of the local resistivities and using a common statistical Random Resistor Network approach.

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Section: Introductionmentioning

confidence: 99%

Random resistivity network calculations for cuprate superconductors with an electronic phase separation transition

Pinheiro¹,

Mello²

2012

Physica A: Statistical Mechanics and its Applications

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“…To obtain the measured values of T c , we notice that the EPS transition, with the free energy walls and wells, makes the structure of the system similar to granular superconductors [35]. In this way, it is likely that the superconducting transition occurs in two steps [26,28]: first by intra-grain superconductivity and than by Josephson coupling with phase locking at a lower temperature. This two steps approach is also supported by the two energy scales found in most cuprates [ 36,37], and also in the two different regimes of critical fluctuations in Y Ba 2 Cu 3 O 7 single crystals [38].…”

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confidence: 99%

Description and connection between the oxygen order evolution and the superconducting transition in La ₂ CuO _4+y

Mello¹

2012

EPL

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PACS 74.20.Mn -Nonconventional mechanisms PACS 74.25.Dw -Superconductivity Phase Diagram PACS 74.62.En -Effects of disorder PACS 74.81.Fa -Josephson junction arrays and wire networksAbstract -A recent hallmark set of experiments by Poccia et al in cuprate superconductors related in a direct way, for the first time, time ordering (t) of oxygen interstitials in initially disordered La2CuO4+y with the superconducting transition temperature Tc(t). We provide here a description of the time ordering forming pattern domains and show, through the local free energy, how it affects the superconducting interaction. Self-consistent calculations in this granular structure with Josephson coupling among the domains reveal that the superconducting interaction is scaled by the local free energy and capture the details of Tc(t). The accurate reproduction of these apparently disconnected phenomena establishes routes to the important physical mechanisms involved in sample production and the origin of the superconductivity of cuprates.

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“…This change in the two-body attractive potential is due to a phase segregation of the holes which forms islands of low and high densities. The holes get trapped in these grains, they loose kinetic energy what is a process that favors the pair attraction as discussed previously [13,11,15,16]. Typical solutions of the local d-wave gap ∆ δ (r i ) are shown in the middle panel of Fig.…”

Section: The Modelmentioning

confidence: 61%

“…For instance, for p = 0.1, the local gaps ∆ δ (r i ) vanish near T = 230K. In this way the resistive transition at T c is estimated by the Josephson coupling among these regions [15,16]. As mentioned, Chen and Ting [14] studied this model on homogeneous systems and found that the spin disorder or SDW phase starts near the optimum value using U = 2.44t and |V | = t at all doping and vanishes in the overdoped region.…”

Section: Results and Conclusionmentioning

confidence: 98%

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Competing orders in the phase diagram of cuprate superconductors

Magalhães

Mello

2012

J. Phys.: Conf. Ser.

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Abstract.We perform self-consistent calculations in the framework of the Bogoliubov-deGennes theory with a model Hubbard Hamiltonian with strong local correlations. The calculations are performed in a charge density disordered system to study the competition of charge inhomogeneity, spin disorder and superconductivity These calculations are appropriate to describe the cuprate superconductors' phase diagram with the competition of different phases. We find that, in the presence of charge disorder the spin density wave (SDW) order occurs at higher temperatures above the opening of the superconducting gap. This is in opposition to the homogeneous systems where the SDW phase appears in the low doping compounds in the superconducting phase. These finding provides an explanation to the non-Fermi liquid behavior of the cuprates normal phase. IntroductionThe origin of the superconducting gap associated with the superconducting state and the relation to the pseudogap above the transition temperature (T c ) remains one of the central questions in high-T c research [1,2]. The normal phase properties differs completely from the BCS superconductors. It is a matter of intense debate whether this problem is connected with the charge inhomogeneities observed in many different experiments [3,4,5,6,7,8,9,10].In order to obtain a unified interpretation to all of these observations we studied an electronic phase separation (EPS) transition that generates regions of low and high densities. Such a transition may be driven by the lower free energy of undoped antiferromagnetic (AF) regions[11] (intrinsic) or by the out of plane dopants[12] (extrinsic origin).In this context we perform the study of the the superconducting (SC) and antiferromagnetic (AF) order in a model t-t'-U-V Hamiltonian commonly used to describe the cuprates [13,14] in an electronic disordered system. Chen and Ting [14] have studied this model for different doping and temperature and found that the AF is stronger at low doping and high temperatures. Self-consistent calculations in the Bogoliubov-deGennes (BdG) framework indicates that the AF order persists above the opening of the SC order parameter at very high temperatures. This is used to interpret the normal pseudogap phase, since this type of spin density wave will cause an additional scattering to the electrons and will change the Fermi liquid properties.

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The Two Energy Scales of Tunneling Spectra of Cuprate Superconductors

Cited by 6 publications

References 18 publications

Random resistivity network calculations for cuprate superconductors with an electronic phase separation transition

Random resistivity network calculations for cuprate superconductors with an electronic phase separation transition

Description and connection between the oxygen order evolution and the superconducting transition in La ₂ CuO _4+y

Competing orders in the phase diagram of cuprate superconductors

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The Two Energy Scales of Tunneling Spectra of Cuprate Superconductors

Cited by 6 publications

References 18 publications

Random resistivity network calculations for cuprate superconductors with an electronic phase separation transition

Random resistivity network calculations for cuprate superconductors with an electronic phase separation transition

Description and connection between the oxygen order evolution and the superconducting transition in La 2 CuO 4+y

Competing orders in the phase diagram of cuprate superconductors

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Description and connection between the oxygen order evolution and the superconducting transition in La ₂ CuO _4+y