Electron localization induced by grain boundary disorder in the normal state of high-Tc superconductors |
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Authors: | A M'chirguiM Zouaoui F Ben AzzouzB Yangui M Ben Salem |
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Institution: | Laboratoire de Physique des Matériaux, Département de Physique, Faculté des Sciences de Bizerte, Zarzouna, 7021, Bizerte, Tunisia |
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Abstract: | We have studied the effects of superconducting grain boundary disorder on the normal state transport properties of cuprate films. Dip-coated granular YBa2Cu3O7−y (YBaCuO) thick films on polycrystalline MgO substrates were synthesized and networked grains were systematically made less disordered in order to probe the crossover from strong to weak inter-grain disorder. Grain boundary passivation was achieved by metallic inclusions of different forms. We have shown that the normal state of samples exhibit a semiconducting behavior and changes to ‘metallic’ with sharper transitions to the superconducting state as we reduce grain-interfaces disorder, i.e. increase metallic inclusion content. On the basis of electron localization mechanisms, the normal state conductivity is thus shown to undergo a dimensional crossover from 3D to 2D in the frame of the variable-range hopping (VRH) regime. The transition threshold was found to depend on the form of metallic inclusions. |
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Keywords: | 74 25 &minus q 74 25 Fy 74 72 Bk |
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