  We report on the observation of self-organized stripe-like structures on the
as-grown surface and in the bulk of (Nd,Eu,Gd)Ba$_2$Cu$_3$O$_y$ single
crystals. The periodicity of the stripes on the surface lies between 500 and
800 nm. These are possibly the growth steps of the crystal. Transmission
electron microscopy investigations revealed stripes of periodicity in the range
of 20 to 40 nm in the bulk. From electron back scattered diffraction
investigations, no crystallographic misorientation due to the nanostripes has
been found. Scanning tunneling spectroscopic experiments revealed
nonsuperconducting regions, running along twin directions, which presumably
constitute strong pinning sites.
