Педагогические науки/2. Проблемы подготовки специалистов.

Brukva O.M, Doctor of Phys. and Math. Sci. Reshetnyak S.O.

National Technical University of Ukraine “Kyiv Polytechnic Institute”

Studying the after-action magnetic effect by undergraduates-physicists

In the frameworks of complex teaching of students–physicists, some problems of solid state physics can be studied with the help of such high-technological technic as a scanning tunnel microscope. In particular, we use the scanning tunnel microscope “REMT-100” combined with a raster electronic microscope. Such combination of devises allows to choose roughly the region of detailed exploring by means of electronic microscope and to start immediately the detailed scanning of a surface by means of scanning tunnel microscope with resolving power of several angstroms.

One of the interesting effects which can be proposed to educational process is so called after-action magnetic effect that is observed in granular thin films of CoAg. In such systems, the surface nanostructure of the film is changed after the action of magnetic field, and the changes continuous some time even after switching off the source of magnetic field. At this, during this time the system tries to pass to a new nanostructure state (see figs.1-2).

All the transformation is accompanied with a change of fractal dimension of the surface.

a) b)

Fig.1. STM-image of the area of granular film Со₆₀Аg₄₀: а – before the action of magnetic field; b – immediately after influence of magnetic field Н=3,6 кЕ.

а) after 224 sec; b) after 593 sec;

c) after 980 sec; d) after 1382 sec;

e) after 1820 sec; f) after 2239 sec

Fig.2. STM-images of the area of granular film Со₆₀Аg₄₀ after single influence of magnetic field.

Note that change of fractal dimension is more essential starting from some value of external magnetic field.

So, such experiment is an example of one of the methods to form and change the nanostructure of surface of granular films by means of external magnetic field and can expand the knowledge of students as for magnetic characteristics of granular films.