Nanostripes in SmBa2Cu3O7−δ single crystals: Origin and peak effect

Nanoscopic surface stripes were observed in high quality SmBa2Cu3O7−δ single crystals grown by a top-seeded pulling growth and their roles on the peak effect and enhanced flux pinning were investigated with a SQUID magnetometer. The crystal surface exhibited an ordered modulation with a roughness of 1-2 nm and a wavelength of about 50 nm. The study evidenced that such a periodic array is not dependent on surface processing. The analysis further unveiled that nanoscaled stripes may act as a kind of δTc-style pinning defects which contribute to an enhanced peak effect.