Investigation of the coercive force of thin magnetic films obtained by vacuum sputtering

The investigation of the magnetic properties of thin magnetic films is of great scientific as well as practical interest for two reasons. First, thin magnetic films, being two dimensional (one of the dimensions is much smaller than the others) show novel properties; their study can solve various problems in the theory of ferromagnetism which are difficult to solve using only data obtained from bulk materials 1,2]. Second, scientific and practical interest with respect to thin magnetic films has increased due to their possible practical applications for logic and memory elements in computer technology 3–7].Their coercive force, which is relatively increased with respect to bulk magnetic materials, is one of the basic properties of thin magnetic films. As is known, the coercive force of thin magnetic films is one of the most important design parameters for memory and logic elements in computer technology, since the coercive force defines the current necessary for the reversal of the magnetic polarity. Although this parameter is of great importance and intensive investigations of it have been carried out, precise data do not yet exist. As a matter of fact, the existing data are often contradictory, because basic technological factors were not taken into account in the investigations.To illustrate the above we give the results of a number of experimental studies in which attempts were made to establish the dependence of the coercive force upon the thickness of the magnetic film as shown in Fig. 1 (curves 2,3,4,7,15,17). Curve 16 is a calculated curve, the other curves refer to thin magnetic films obtained by various authors using the electrolytic depositing method.From this data it is evident that the magnitude of the coercive force for a certain thickness of thin magnetic film, prepared from the same magnetic material according to the same method, assumes different values with different authors. This is explained by the fact that the investigation of the dependence of the coercive force upon the film thickness is extremely complex because it is difficult to control the basic technological factors and also because various additional factors come into play which were not taken into account by the authors.