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A single domain REBCO bulk, fabricated with one seed whether by the top seeded melt growth method or top seeded infiltration growth (TSIG) process, consists of five growth sectors (GSs) generally. In this paper, we report a new method for batch production of single domain GdBCO bulks with one seed, but of different growth sectors (n-GSs, n = 2, 3, 5) by the RE+011 TSIG process. It is found that four single domain GdBCO bulks with 2-GSs and 3-GSs can be fabricated with a buffer added one seed method. The levitation forces and trapped fields indicate that the physical properties of samples decrease with the decreasing of the n-GSs, such as the largest levitation force and trapped field is achieved in the sample with 5-GSs, the smallest one is obtained in the sample with 2-GSs, and the middle one is obtained in the sample with 3-GSs. This is closely related to the number n of GSs which can lead to a different thickness of n-GSs and the pure c-GSs; these results have been studied in detail. This work provided a new effective way to improve the seed efficiency for the fabrication of single domain REBCO bulk superconductors.

To study the influence of thickness on the magnetic properties of REBCO (RE = Y, Gd, Sm, Nd, etc.) bulk superconductors, a single domain gadolinium barium copper oxide (GdBCO) bulk superconductor fabricated by the RE + 011 top seeded infiltration growth (RE + 011 TSIG) method was continuously sliced along the bottom to obtain samples of different thickness. The levitation force and attractive force of these samples were tested at 77 K in the zero-field-cooled (ZFC) state. It was found that as the sample thickness decreases, the levitation force decreases gradually whereas the attractive force increases. This is related to the varied ability to resist the penetration of magnetic field occasioned by varying sample thickness, which were deeply revealed combined with the characteristics of the non-ideal type-II superconductor. Further, the levitation force exhibits a trend of slow initial change followed by rapid change, which may be attributed to the growth of the sample. Measurement of the trapped field shows that a similar distribution of trapped field at the top and bottom surfaces can be achieved by removing some materials from the bottom of the bulk. These results provide a reference for meeting the actual requirements of REBCO bulks of different thicknesses and greatly contribute to practical design and application. Keywords: single domain GdBCO bulk superconductor; thickness; levitation force; attractive force

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