Josephson coupling in high-T$_c$ superconducting junctions using ultra-thin BaTiO$_3$ barriers

H. Navarro; M. Sirena; Jeehoon Kim; N. Haberkorn

doi:10.1016/j.mseb.2020.114714

paper

Josephson coupling in high-T $_{c}$ superconducting junctions using ultra-thin BaTiO $_{3}$ barriers

arXiv:2005.01236 · doi:10.1016/j.mseb.2020.114714

Abstract

We study the electrical transport of vertically-stacked Josephson tunnel junctions using GdBa $_{2}$ Cu $_{3}$ O $_{7 - d}$ electrodes and a BaTiO $_{3}$ barrier with thicknesses between 1 nm and 3 nm. The junctions with an area of 20 mm x 20 mm were fabricated combining optical lithography and ion etching using GdBa $_{2}$ Cu $_{3}$ O $_{7 - d}$ (16 nm) / BaTiO $_{3}$ (1 - 3 nm) / GdBa $_{2}$ Cu $_{3}$ O $_{7 - d}$ (16 nm) trilayers growth by sputtering on (100) SrTiO $_{3}$ . Current-voltage measurements at low temperatures show a Josephson coupling for junctions with BaTiO $_{3}$ barriers of 1 nm and 2 nm. Reducing the barrier thickness bellow a critical thickness seems to suppress the ferroelectric nature of the BaTiO $_{3}$ . The Josephson coupling temperature is strongly reduced for increasing barrier thicknesses, which may be related to the suppression of the superconducting critical temperature in the bottom GdBa $_{2}$ Cu $_{3}$ O $_{7 - d}$ due to stress. The Josephson energies at 12 K are of $\approx$ 1.5 mV and $\approx$ 7.5 mV for BaTiO $_{3}$ barriers of 1 nm and 2 nm. Fraunhofer patterns are consistent with fluctuations in the critical current due to structural inhomogeneities in the barriers. Our results are promising for the development of Josephson junctions using high-T $_{c}$ electrodes with energy gaps much higher than those usually present in conventional low-temperature superconductors.

Josephson coupling in high-Tc​ superconducting junctions using ultra-thin BaTiO3​ barriers

Abstract

References in corpus (6)

Josephson coupling in high-T $_{c}$ superconducting junctions using ultra-thin BaTiO $_{3}$ barriers