Magnetic dots imaging

In magnetic printers, the basic idea is to form a latent image by means of a magnetic drum and a system of magnetic heads. Each magnetic head produces a row of tiny magnetic dots on the drum combined with the drum rotation, this step leads to the image to be printed. In the next step. 

NANOSCALE MAGNETIC ELEMENTS, MAGNETIC DOTS IMAGING... 

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. 

Fig. 5.3-36 Structural (a) and magnetic (b) images of an array of single-domain dots with a 60 nm pitch prepared by nanoimprinting and coating with a (Pt/Co) multilayer. Images obtained by atomic and magnetic force microscopy...

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