New type of vortex pinning structure effective at very high magnetic fields

• Published in: Physical review letters Vol. 89; no. 23; p. 237001
• Main Authors: Muralidhar, M, Sakai, N, Chikumoto, N, Jirsa, M, Machi, T, Nishiyama, M, Wu, Y, Murakami, M
• Format: Journal Article
• Language: English
• Published: United States 02-12-2002
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/physrevlett.89.237001

We report on a new type of correlated nanometer-scale pinning structure observed in a melt-processed (Nd0.33Eu0.38Gd0.28)Ba(2)Cu(3)O(y) (NEG-123). It consists of NEG/Ba-rich clusters in the stoichiometric NEG-123 matrix forming a lamellar array with a period of a few nanometers. These lamellas appear within regular twins, thus representing their fine substructure-sometimes straight, sometimes wavy. This new material structure correlates well with the significant enhancement of pinning at high fields, represented by irreversibility field above 14 T at 77 K (B parallel c). We believe that the new pinning medium enables one to significantly broaden the limits for high-field applications.