43,216 research outputs found

    High-Tc superconductivity originated from strong spin-charge correlation: indication from linear temperature dependence of resistivity

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    Both the highest- and the linear temperature dependence of the resistivity in wide temperature range appear at the optimally doped regions of Cu-based superconductors1,2,3,4,5, and the highest- of Fe-based superconductors6,7 are also associated with the linear temperature dependence of the resistivity in normal states near superconducting states. This means that the high temperature superconductivity and the linear temperature dependence of the resistivity should be dominated by the same mechanism. This letter on theoretic calculation clearly shows that strong spin-charge correlation dominated resistivity behaves the linear temperature dependence, thus high-temperature superconductivity should be induced by strong spin-charge correlation.Comment: 4pages,V1 has to be delete

    Basic principle of superconductivity

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    The basic principle of superconductivity is suggested in this paper. There have been two vital wrong suggestions on the basic principle, one is the relation between superconductivity and the Bose-Einstein condensation (BEC), and another is the relation between superconductivity and pseudogap.Comment: 4 gage

    Basic physics of solid materials

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    Since the cuprate materials behave many curious properties, the mechanism that causes high-temperature superconductivity in copper oxide materials (cuprates) has been a controversial topic. To explain these curious properties, we must look out the physics what these materials include. In this letter, it is presented that there are the basic physics (1)-(9) in solid materials. I divide all solid materials into four categories, explain some properties of them qualitatively, and suggest some ways to turn a solid material into a superconductor. Particularly, this letter discusses the differences between the p-type high-Tc cuprate superconductors, the n-type superconductor Nd2-xCexCuO4, the BCS-superconductor similar MgB2, and heavy Fermions superconductors.Comment: 5 pages, 3 figures; a new (recent) pape

    Pairing with non-opposite momentum in superconductors

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    The basic feature of the BCS theory is that pairing occurs between electrons in states with opposite momentum and opposite spins, e.g., between states (k) and (-k), in which the symbols of vectors are neglected, and later theories followed the BCS theory. However, since the center of mass for any pair is not always static, we must consider the pairing between states (k) and (-k+q). In this letter, we derive a set of self-consistent equations for the correlation functions associated with the pairs that have non-opposite momentums, in which we find some new results. This means that some physics associated with superconductors should be re-explained in futures.Comment: 2pages, 0figure

    Possible temperature control DC switch effect between two superconductors

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    The lifetime of an electron pair could not be unlimited long, on the basis of this, we suggest a model. The model means that the movements of charge carriers in a superconductor should have three forms: the single-electron movement, the single-pair movement, and the revolving around the mass center of two electrons in a pair. Thus the current in a superconductor has three possible parts. Similarly, there should be three possible effects in a SIS junction: the tunneling of single electron, the tunneling of single pair, and the pair-forming following the pair-breaking. This paper will discuss these problems and present a possible temperature control DC switch effect between two superconductors.Comment: superconductivity, 9page

    Reverse circling supercurrents along a superconducting ring

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    The reason why high temperature superconductivity has been being debated is that many basic ideas in literatures are wrong. This work shows that the magnetic flux quantum in a superconducting ring have been inaccurately explained in fact, thus we suggest a reinterpretation of the magnetic flux quantum in a superconducting ring on the basis of the translations of pairs. We also predict that the internal and external surface of a superconducting tube have the reverse circling supercurrents. This means that a more thick tube could trap a larger amount of flux. Both the magnetic flux quantum and the reverse circling supercurrents could not be found with the London equation.Comment: superconductivity;6page

    Superconductors described with CSM.(a new paper, 2008-10-16)

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    The properties of the known superconductors can be explained with the correlations dominated superconducting mechanism (CSM). The correlations have the spin correlation, the charge correlation and the spin-charge correlation, and their strengths can be described by the related correlation lengths in their correlation functions. Our evaluation from many superconductors is that superconductivities occur if both the spin correlation and the charge correlation are stronger, and the calculation of a Hubbard model showed that the spin-charge correlation may govern superconductivities1. Afterwards, this mechanism has led a model which includes various superconductivities and magnetisms, and the relation between superconductivities and magnetisms can be understood on this model2 (these results have been shown by calculations). This mechanism is very practical, for example, to turn a material into a superconductor or increase the Tc of a superconductor, what we will do is to increase the spin-charge correlation. In this letter, we first describe the relations between the spin-charge correlation, the spin correlation and the charge correlation, take these relations as the basis of constructing a new phase diagram, and then classify the known superconductors into various sections in this phase diagram. This letter also gives a new explanation about the pressure effect on Tc, the isotope effect on Tc and the pairing symmetry with the CSM.Comment: 4 pages,2 tables, 1 figur

    Coincidence Subwavelength Interference by a Classical Thermal Light

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    We show that a thermal light random in transverse direction can perform subwavelength double slit interference in a joint-intensity measurement. This is the classical version of quantum lithography, and it can be explained with the correlation of rays instead of the entanglement of photons.Comment: 4 pages, 2 figure

    Quantum Lithography in Macroscopic Observations

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    We study the generalized Young's double-slit interference for the beam produced in the spontaneously parametric down-conversion (SPDC). We find that the sub-wavelength lithography can occur macroscopically in both the two-photon intensity measurement and the single-photon spatial intensity correlation measurement. We show the visibility and the strength of the interference fringe related to the SPDC interaction. It may provide a strong quantum lithography with a moderate visibility in practical application.Comment: 6 pages, 5 Postscript figures, uses revte

    N-photon Correlation Functions in N-slit Diffraction Experiments with Thermal Light

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    We discuss the analytic presentations of the high-order correlation functions in the N-slit diffraction with thermal light in a recent paper [Phys. Rev. Lett. 109, 233603 (2012)]. Our analysis shows that the superresolving fringes in the high-order correlation measurement have two classical counterparts.Comment: 4 pages, 1 figur
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