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| Author | Navarro, H.; Yang, I.; Sirena, M.; Kim, J.; Haberkorn, N. | ||||
| Title | Characterization of the insulator barrier and the superconducting transition temperature in GdBa2Cu3O7−δ/BaTiO3 bilayers for application in tunnel junctions | Type | Journal Article Article | ||
| Year | 2015 | Publication | Journal of Applied Physics | Abbreviated Journal | J. Appl. Phys. |
| Volume | 118 | Issue | 4 | Pages | 045308 |
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| Abstract | The optimization of the superconducting properties in a bottom electrode and the quality of an insulator barrier are the first steps in the development of superconductor/insulator/superconductor tunnel junctions. Here, we study the quality of a BaTiO3 tunnel barrier deposited on a 16 nm thick GdBa2Cu3O7−δ thin film by using conductive atomic force microscopy. We find that the tunnel current is systematically reduced (for equal applied voltage) by increasing the BaTiO3 barrier thickness between 1.6 and 4 nm. The BaTiO3 layers present an energy barrier of ≈1.2 eV and an attenuation length of 0.35–0.5 nm (depending on the applied voltage). The GdBa2Cu3O7−δ electrode is totally covered by a BaTiO3 thickness above 3 nm. The presence of ferroelectricity was verified by piezoresponse force microscopy for a 4 nm thick BaTiO3 top layer. The superconducting transition temperature of the bilayers is systematically suppressed by increasing the BaTiO3 thickness. This fact can be associated with stress at the interface and a reduction of the orthorhombicity of the GdBa2Cu3O7−δ. The reduction in the orthorhombicity is expected by considering the interface mismatch and it can also be affected by reduced oxygen stoichiometry (poor oxygen diffusion across the BaTiO3 barrier). | ||||
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| Notes | Approved | no | |||
| Call Number | BT @ pedrazp @ | Serial | 727 | ||
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