Properties of Patterned Thin Films

An example is shown in Fig. 15. In this case for each image the field is increased to a certain value and taken back to zero, in order to minimize the influence of the tip on the sample. The first image of Fig. 15(a) shows the magnetization after applying -1353 kA/m perpendicular to the sample. The tip and medium are saturated in the same direction so only attractive forces occur (black dots). When field is increased to +4 kA/m, the tip reverses magnetization and all forces become repulsive, so the contrast reverses (white dots). At 127 kA/m almost 50% of the dots is reversed (Fig. 15(c)) and at 183 kA/m almost all the dots are reversed (Fig. 15(d)). The first dots switch already at 80 kA/m, but the last at 192 kA/m. 

The energy barrier height of reversal is estimated as 1.0 x 10 10 erg. The energy corresponds to the switching volume comparable with the volume of 

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