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TT: Tiefe Temperaturen

TT 7: Superconductivity & Solids At Low Temperature - Poster Session

TT 7.19: Poster

Montag, 27. März 2006, 14:00–17:45, P1

Nanoscale stripe structures in SmBa₂Cu₃O_x superconductors — •M. Winter¹, M. R. Koblischka¹, Th. Wolf², X. Yao³, A. Hu⁴, and U. Hartmann¹ — ¹Institute of Experimental Physics, University of Saarbrücken, P.O.Box 151150, 66041 Saarbrücken, Germany — ²Forschungzentrum Karlsruhe GmbH, Institute of Solid State Physics, D-76021, Karlsruhe, Germany — ³Department of Physics, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030, P. R. China — ⁴Department of Physics, University of Waterloo, 200 Univ. Ave. West, Waterloo, ON N2L 3P7, Canada

AFM and STM scans on SmBa₂Cu₃O_x (SmBCO) melt-processed samples prepared using different techniques revealed the presence of nanoscale stripe-like structures, sometimes parallel over several micrometers, sometimes wavy. These structures consist of chemical compositional fluctuations and act as effective δ T_c pinning centers due to their wavelength of typically 10-60 nm which is comparable to the ideal pinning-center size of 2 ξ ( 10 nm for YBa₂Cu₃O_x in the ab-plane). Compared to similar structures in ternary (Sm,Eu,Gd)Ba₂Cu₃O_x (SEG) and (Nd,Eu,Gd)Ba₂Cu₃O_x (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 1 Å- 8Å. These pinning structures throughout the whole sample volume may be a key to improve critical current densities especially at high external magnetic fields.