Structural Properties and Hopping Conduction in the Normal State of Electron-Doped Superconductor Cuprate Eu_2–xCe_xCuO_4+α–δ

Abstract

Electron-doped superconducting cuprate of Eu 2– x Ce x CuO 4+α–δ has been studied in the whole doping regime from x = 0.10–0.20 with reducing oxygen content to investigate the relation between the crystal structure and the hopping conduction in the normal state. Parameter of the crystal structure has been extracted from the X-ray diffraction (XRD) measurement while hopping conduction parameters have been obtained from resistivity measurements. The Eu–O bond length decreases with the increasing doping concentration, indicating the successful doping by the partial replacing of Eu 3+ with Ce 4+ . The resistivity increases with decreasing temperature in all measured samples. This is an indication of bad metal-like behavior in the whole regime in the normal state of electron-doped superconducting cuprate of Eu 2– x Ce x CuO 4+α–δ . The temperature dependence of resistivity was analyzed by the Arrhenius law and the variable range hopping model. It is found that the hopping conduction mechanism more likely follows the variable range hopping rather than the Arrhenius law, indicating that the hopping mechanism occurs in three dimensions. The Cu–O bond length probably plays an important role in decreasing the activation energy. The decreasing value of the activation energy correlates with the increase in the localization radius.

Dependence of critical temperature on doping and oxygen reduction in Nd2-xCexCuO4-δ${\rm Nd}_{2{\hbox{-}}x}{\rm Ce}_x{\rm CuO}_{4{\hbox{-}}\delta}$ superconductor

“…For the experimental value of Eu 2-x Ce x CuO 4−𝛿 , T c = 12 K, [22] 𝑘 𝐵 = 1.38 x 10 −23 J∕K, then we get, Δ se (0) = 2.91 x10 −22 J and similarly for Nd 2-x Ce x CuO 4−𝛿 at T c = 25 K, [5] Δ se (0) = 6.06165 x 10 −22 J.…”

“…Experimental [11,22] contribute to electron pairing. [23,24] Thus, the superconducting and magnetic behavior of the phase diagram is important when investigating the correlation between magnetism and superconductivity [25] typically in LCCO system.…”

“…[26] In such system, the Eu − O bond length decreases with increasing doping concentration (x), indicating the successful doping by the partial replacement of Eu 3+ or Nd 3+ by Ce 4+ . [22] Ĥ𝑒−𝑏 describes the BCS type electronelectron interactions that are suggested to be mediated by boson [23] and is given by,…”

Investigation on Magnetotransport Properties and Specific Heat Capacity of FeTe0.58Se0.42 Single Crystals Grown by Self‐Flux Method

“…Similar broadening is also observed in other FBSCs [ 40,47,48 ] and cuprates superconductors. [ 49,50 ] Arrhenius law gives a relationship between resistivity and thermally activated energy () as follows: [ 51 ] where is the normal state resistivity and is the Boltzmann constant.…”

“…Similar broadening is also observed in other FBSCs [40,47,48] and cuprates superconductors. [49,50] Arrhenius law gives a relationship between resistivity ρ ð Þ and thermally activated energy (U 0 ) as follows: [51] ρ…”