Temperature Dependence of the Electrical Resistivity of Electron-Doped Cuprates
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ONIC PROPERTIES OF SOLID
Temperature Dependence of the Electrical Resistivity of Electron-Doped Cuprates N. A. Babushkinaa,*, A. A. Vladimirovb, K. I. Kugelc,d, and N. M. Plakidab a
National Research Center “Kurchatov Institute,” Moscow, 123182 Russia Joint Institute for Nuclear Research, Dubna, Moscow oblast, 141980 Russia c Institute for Theoretical and Applied Electromagnetics, Russian Academy of Sciences, Moscow, 125412 Russia d National Research University Higher School of Economics, Moscow, 101000 Russia *e-mail: [email protected] b
Received March 25, 2020; revised March 25, 2020; accepted April 20, 2020
Abstract—Experimental data on the temperature dependence of electrical resistivity are analyzed for electron-doped Nd2– xCexCuO4– δ cuprates in a wide range of cerium concentrations 0.12 ≤ x ≤ 0.20. It is shown that, in a wide temperature range above the superconducting transition temperature, the electrical resistivity mainly exhibits quadratic temperature dependence and decreases sharply at concentrations of x ≥ 0.17. Theoretical analysis based on the microscopic t – J model for strongly correlated electrons shows that the quadratic temperature dependence of electrical resistivity is attributed to electron scattering by spin excitations. To describe these excitations, a model of antiferromagnetic (AFM) spin fluctuations in the paramagnetic phase is proposed; the intensity of these fluctuations depends on the AFM correlation length. The quadratic temperature dependence of electrical resistivity agrees well with experimental data. DOI: 10.1134/S1063776120090022
1. INTRODUCTION More than 30 years have passed since Bednorz and Müller discovered high-temperature superconductivity in cuprates [1]. During this time, many new classes of high-temperature superconductors, and not only cuprate ones, were found. The superconducting transition temperature has been elevated significantly. However, despite the tremendous progress in this area, many important problems, even in the field of cuprates, are still quite far from the complete solution (see, for example, [2]). One of these problems is the strong asymmetry of the electronic characteristics of hole- and electron-doped cuprates. Indeed, if we look at the phase diagram of superconducting cuprates [3], we see that, in the electron doping region, superconductivity exists in a narrow range of concentrations of the doping element, whereas the region of existence of the antiferromagnetic (AFM) state occupies a significantly larger area. Moreover, while, in hole cuprates, the superconducting and AFM regions are relatively far apart from each other, in electron cuprates, these regions almost overlap. The presence of a broader AFM region indicates the existence of stronger AFM correlations in electron superconductors, which is confirmed by a detailed theoretical analysis of the differences between electron and hole superconductors within actively used model approaches [4].
Generally speaking, spin fluctuations play an important role in both electron and hole cuprate
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