AFM and STM scans on SmBa2Cu3Ox (SmBCO) melt processed samples revealed nanoscale stripe-like structures, sometimes parallel over several micrometers, sometimes wavy. These structures consist of chemical compositional fluctuations and act as effective δTc pinning centres due to their wavelength of typically 10-60 nm which is comparable to the ideal pinning center size 2ξ (∼10 nm for YBa 2Cu3Ox in the ab-plane). Compared to similar structures in ternary (Sm, Eu, Gd)Ba2Cu3Ox (SEG) and (Nd, Eu, Gd)Ba2Cu3Ox (NEG) systems, where the stripes appear either as plateau-like stripes or as chains of aligned clusters, the stripes in SmBCO always appear as plateau-like stripes with a height of 1Å-8. These pinning structures throughout the whole sample volume may be a key to improve critical current densities especially at high external magnetic fields.
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