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Abstract |
We report the electrical transport properties of conducting/insulator/conducting heterostructures by studying current–voltage IV curves at room temperature. The measurements were obtained on tunnel junctions with different areas (900, 400 and 100 μ m 2 ) using a conducting atomic force microscope. Trilayers with GdBa 2 Cu 3 O 7 (GBCO) as the bottom electrode, SrTiO 3 or BaTiO 3 (thicknesses between 1.6 and 4 nm) as the insulator barrier, and GBCO or Nb as the top electrode were grown by DC sputtering on (100) SrTiO 3 substrates For SrTiO 3 and BaTiO 3 barriers, asymmetric IV curves at positive and negative polarization can be obtained using electrodes with different work function. In addition, hysteretic IV curves are obtained for BaTiO 3 barriers, which can be ascribed to a combined effect of the FE reversal switching polarization and an oxygen vacancy migration. For GBCO/BaTiO 3 /GBCO heterostructures, the IV curves correspond to that expected for asymmetric interfaces, which indicates that the disorder affects differently the properties at the bottom and top interfaces. Our results show the role of the interface disorder on the electrical transport of conducting/insulator/conduction heterostructures, which is relevant for different applications, going from resistive switching memories (at room temperature) to Josephson junctions (at low temperatures). |
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