Importance of grain boundary Josephson junctions in the electron-doped infinite-layer cuprate superconductor Sr${}_{1-x}$La${}_x$CuO${}_2$

Abstract

Grain boundary bicrystal Josephson junctions of the electron-doped infinite-layer superconductor Sr${}_{1-x}$La${}_x$CuO${}_2$ ($x=0.15$) were grown by pulsed laser deposition. BaTiO${}_3$-buffered $24{}^{\circ }$ [001]-tilt symmetric SrTiO${}_3$ bicrystals were used as substrates. We examined both Cooper pair (CP) and quasiparticle (QP) tunneling by electric transport measurements at temperatures down to 4.2\,K. CP tunneling revealed an extraordinary high critical current density for electron-doped cuprates of $j_c>10^3$A/cm${}^2$ at 4.2\,K. Thermally activated phase slippage was observed as dissipative mechanism close to the transition temperature. Out-of-plane magnetic fields $H$ revealed a remarkably regular Fraunhofer-like $j_c(H)$ pattern as well as Fiske and flux flow resonances, both yielding a Swihart velocity of $3.1\cdot 10^6$m/s. Furthermore, we examined the superconducting gap by means of QP tunneling spectroscopy. The gap was found to be V-shaped with an extrapolated zero temperature energy gap ${\Delta }_0\approx 2.4$meV. No zero bias conductance peak was observed.

6 pages, 3 figures

References in corpus (3)

• Andreev - Saint James reflections: a probe of cuprate superconductors
• Phase-sensitive order parameter symmetry test experiments utilizing Nd2-xCexCuO4-y/Nb zigzag junctions
• Andreev bound states at a cuprate grain boundary junction: A lower bound for the upper critical field

Cited by in corpus (1)

• Phase-sensitive evidence for dx2-y2-pairing symmetry in the parent-structure high-Tc cuprate superconductor Sr1-xLaxCuO2