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تسجيل مستخدم جديدUniversal scaling behavior of the c-axis resistivity of high-temperature superconductors
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We propose and show that the c-axis transport in high-temperature superconductors is controlled by the pseudogap energy and the c-axis resistivity satisfies a universal scaling law in the pseudogap phase. We derived approximately a scaling function for the c-axis resistivity and found that it fits well with the experimental data of Bi$_2$Sr$_2$CaCu$_2$O$_{8+delta}$, Bi$_2$Sr$_2$Ca$_2$Cu$_3$O$_{10+delta}$, and YBa$_2$Cu$_3$O$_{7-delta}$. Our works reveals the physical origin of the semiconductor-like behavior of the c-axis resistivity and suggests that the c-axis hopping is predominantly coherent.
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Scaling laws express a systematic and universal simplicity among complex systems in nature. For example, such laws are of enormous significance in biology. Scaling relations are also important in the physical sciences. The seminal 1986 discovery of h
igh transition-temperature (high-T_c) superconductivity in cuprate materials has sparked an intensive investigation of these and related complex oxides, yet the mechanism for superconductivity is still not agreed upon. In addition, no universal scaling law involving such fundamental properties as T_c and the superfluid density rho_s, a quantity indicative of the number of charge carriers in the superconducting state, has been discovered. Here we demonstrate that the scaling relation rho_s propto sigma_{dc} T_c, where the conductivity sigma_{dc} characterizes the unidirectional, constant flow of electric charge carriers just above T_c, universally holds for a wide variety of materials and doping levels. This surprising unifying observation is likely to have important consequences for theories of high-T_c superconductivity.
Universal scaling relations are of tremendous importance in science, as they reveal fundamental laws of nature. Several such scaling relations have recently been proposed for superconductors; however, they are not really universal in the sense that s
ome important families of superconductors appear to fail the scaling relations, or obey the scaling with different scaling pre-factors. In particular, a large group of materials called organic (or molecular) superconductors are a notable example. Here, we show that such apparent violations are largely due to the fact that the required experimental parameters were collected on different samples, with different experimental techniques. When experimental data is taken on the same sample, using a single experimental technique, organic superconductors, as well as all other studied superconductors, do in fact follow universal scaling relations.
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We show that the resistivity in each phase of the High-Tc cuprates is a special case of a general expression derived from the Kubo formula. We obtain, in particular, the T-linear behavior in the strange metal (SM) and upper pseudogap (PG) phases, the
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