Field dependence of for a bulk sample at .
Field dependence of the relative decrease of with field, , for the same sample as in Fig. 1 at .
Temperature dependence of the transition field for several different samples: HIP-ed with volume of (open squares) and (solid squares), commercial powder with particle size less than (solid circles), which was subsequently ground to obtain particles smaller than (open circles).
The dependence of the transition field on the volume of the HIP-ed sample, for , 20 and . extrapolates to zero at for all three temperatures.
The dependence of the transition field on the sample length, for the core of an iron-sheathed wire. The diameter of the core was constant, . Inset: The dependence of on the diameter of the core for an iron-sheathed wire, where the length of the core was kept constant, at . The temperature was .
The dependence of the transition field on the volume of the HIP-ed , for , 20 and .
Magnetooptical image for a HIP-ed sample at . The bar represents .
Optical image for the same HIP-ed sample as in Fig. 7. The bar represents .
Schematic drawing of the screening currents in the sample. and are drawn by solid and dotted lines, respectively. The screening currents on lengthscale are represented by the dots. The shaded ellipses are the voids in the sample.
The field dependence of for the HIP-ed sample with volume of , at . Solid line is the fit using Eq. (3), with , , , , and . Solid and dotted lines show separately the first and second part of the Eq. (3), respectively. Solid squares are calculated in the critical state model, with values of obtained from the transport measurements, for an iron-sheathed wire at .
Scanning electron microscope image of a HIP-ed sample at two different magnifications. The sample was broken off a larger pellet, without polishing, to reveal the finer structure of clusters in the cells.
Article metrics loading...
Full text loading...