“…Such variation with a steep increase of the switching field close to the hard axis direction is typical of nonuniform reversal process, such as Kondorsky type (Kondorsky, 1937), curling (Aharoni, 1966;Frei et al, 1957), or fanning (chain of spheres) (Aharoni, 1966). The reversal mode of the magnetic subunits has therefore been discussed with reference to these models (Richter, 1993a;Speliotis and Judge, 1991;Sugita et al, 1999;Victora, 1987;Wierenga et al, 2000).…”