  We report the magnetization losses in an experimental multifilament coated
conductor. A 4 mm wide and 10 cm long YBCO coated conductor was subdivided into
eight 0.5 mm wide filaments by laser ablation and subjected to post-ablation
treatment. As the result, the hysteresis loss was reduced, as expected, in
proportion to the width of the filaments. However, the coupling loss was
reduced dramatically, and became practically negligible, in the range of a
sweep rate up to 20 T/s. This represents a drastic improvement on previous
multifilament conductors in which often the coupling losses became equal to the
hysteresis loss at a sweep rate as low as 3-4 T/s. These results demonstrate
that there is an effective and practical way to suppress coupling losses in
coated multifilament conductors.
