Locally ordered regions in the phase transition in the systems with a finite-range correlated quenched disorder

Wu, Xintian

doi:10.1016/j.physa.2007.05.003

Cited by 3 publications

(2 citation statements)

References 32 publications

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“…[4][5][6] The size of LOR depends on the doping concentration p in the following way R 0 ϳ͓p͑1− p͔͒ −1 . 22 However the present experimental data is not enough to test this prediction.…”

Section: Summary and Discussionmentioning

confidence: 73%

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Excited states of the saddle point equation of the Landau-Ginzburg-Wilson Hamiltonian with random temperature

2009

Phys. Rev. B

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The phase transition in quenched disordered systems is studied on the level of the saddle point solution. Two-dimensional saddle point equation of the Landau-Ginzburg-Wilson Hamiltonian with random temperature is numerically solved for the excited states. It is shown that the excited-state solutions can be described by the domain walls. The length of domain wall and the free energy increase due to the domain wall are calculated. On the level of the saddle point solution the partition function can be mapped to an Ising model approximately. The coupling between Ising spin is estimated. The phase transition is discussed according to this Ising model. It is found that there are two classes of phase transition: inhomogeneous and homogeneous. Different from the pure system, for the phase transition in disordered systems there are fluctuations on the level of saddle point solution.

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Section: Summary and Discussionmentioning

confidence: 73%

“…[20][21][22] The numerical solutions show LOR explicitly. However these solutions are only concerned with the ground state rather than the excited states.…”

Section: Introductionmentioning

confidence: 99%

Excited states of the saddle point equation of the Landau-Ginzburg-Wilson Hamiltonian with random temperature

2009

Phys. Rev. B

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Locally ordered regions and the first-order phase transition in the disordered systems

Jiang

2008

Physica B: Condensed Matter

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Quantum percolation in cuprate high-temperature superconductors

Phillips

2008

Proc. Natl. Acad. Sci. U.S.A.

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Although it is now generally acknowledged that electron-phonon interactions cause cuprate superconductivity with Tc values Ϸ100 K, the complexities of atomic arrangements in these marginally stable multilayer materials have frustrated both experimental analysis and theoretical modeling of the remarkably rich data obtained both by angle-resolved photoemission (ARPES) and highresolution, large-area scanning tunneling microscopy (STM). Here, we analyze the theoretical background in terms of our original (1989) model of dopant-assisted quantum percolation (DAQP), as developed further in some two dozen articles, and apply these ideas to recent STM data. We conclude that despite all of the many difficulties, with improved data analysis it may yet be possible to identify quantum percolative paths.dopant ͉ superconductivity P ercolation in strongly disordered materials cannot be treated analytically, and early discussions of percolation focused on lattice model simulations. Recent discussions are much more sophisticated, and include many off-lattice effects connected with nanoscale phase separation, especially in glassy materials (1-7). The case of cuprate electronic high-temperature superconductive (HTSC) glasses (disordered dopants in a crystalline host) is especially intriguing, as scanning tunneling microscopy (STM) measures local gaps directly. Long ago, we suggested (8) that the dopants (usually oxygen interstitials), added to the insulating host crystal to make it metallic, should not be regarded as donating carriers to the cuprate planes (the most common theoretical model in the early days), but should instead be regarded as electronic bridges connecting metallic nanodomains separated by insulating domain walls generated by planar lattice buckling. This model has several advantages: it recognizes the lattice instabilities that are ubiquitous in perovskite and pseudoperovskites, and the dopants can function as centers of strong electron-phonon interactions.The foregoing dopant-assisted quantum percolation (DAQP) model, with its roots in materials science, initially enjoyed little popularity, because many theorists found more exotic models (not involving attractive electron-phonon interactions at all) more suitable (9-11). However, as we analyzed in many articles (12), the accumulation of data showing large strain effects (13) provided little support for exotic models. There is now a complete picture of the phase diagrams of lattice instabilities (pseudogaps) and superconductive gaps within the DAQP model (14). Nevertheless, the intriguing question of whether these percolation paths can actually be identified in cuprate planes studied by STM remains open. Why has this problem proved to be so difficult?There are several answers to this question. Distinguishing between strain-related pseudogaps and superconductive gaps with only a local probe is difficult, because both gaps are pinned by the Fermi line, and both are intrinsically nonlocal. This means that studies with a local STM probe inevitably see only the projec...

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Locally ordered regions in the phase transition in the systems with a finite-range correlated quenched disorder

Cited by 3 publications

References 32 publications

Excited states of the saddle point equation of the Landau-Ginzburg-Wilson Hamiltonian with random temperature

Excited states of the saddle point equation of the Landau-Ginzburg-Wilson Hamiltonian with random temperature

Locally ordered regions and the first-order phase transition in the disordered systems

Quantum percolation in cuprate high-temperature superconductors

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