Imaging of order parameter induced $\pi$ phase shifts in cuprate superconductors by low-temperature scanning electron microscopy

Abstract

Low-temperature scanning electron microscopy (LTSEM) has been used to image the supercurrent distribution in ramp-type Josephson junctions between Nb and either the electron-doped cuprate Nd${}_{2-x}$Ce${}_x$CuO${}_{4-y}$ or the hole-doped cuprate YBa${}_2$Cu${}_3$O${}_7$. For zigzag-shaped devices in the short junction limit the critical current is strongly suppressed at zero applied magnetic field. The LTSEM images show, that this is due to the Josephson current counterflow in neighboring 0 and $\pi$ facets, which is induced by the $d_{x^2-y^2}$ order parameter in the cuprates. Thus, LTSEM provides imaging of the sign change of the superconducting order parameter, which can also be applied to other types of Josephson junctions.

4 pages, 3 figures

References in corpus (7)

• Supercurrent reversal in quantum dots
• 0-pi Josephson tunnel junctions with ferromagnetic barrier
• High quality ferromagnetic 0 and pi Josephson tunnel junctions
• Dynamics of semifluxons in Nb long Josephson 0-pi junctions
• The 0 and the pi phase Josephson coupling through an insulating barrier with magnetic impurities
• Observation of Andreev bound states in YBaCuO/Au/Nb ramp-type Josephson junctions
• Geometric pi Josephson junction in d-wave superconducting thin films

Cited by in corpus (8)

• Experimental evidence of a ϕ Josephson junction
• Visualizing supercurrents in ferromagnetic Josephson junctions with various arrangements of 0 and πsegments
• Interference patterns of multifacet 20x(0-pi-) Josephson junctions with ferromagnetic barrier
• Phase-sensitive evidence for dx2-y2-pairing symmetry in the parent-structure high-Tc cuprate superconductor Sr1-xLaxCuO2
• Magnetic field dependence of the critical current in YBa_2Cu_3O_{7-δ}/Au/Nb ramp-zigzag Josephson junctions
• Fractional vortex in asymmetric 0-$\pi$ long Josephson junctions
• Manifestation of the magnetic moments of Cooper pairs in low-temperature properties of superconducting thin-film rings
• Breathing modes of long Josephson junctions with phase-shifts