Phase changes of multiferroic magnetic materials, used in external memory systems

Background and Objectives: A review of studies on technological bases of multiferroic materials for their possible use in devices for the urgent destruction of information is presented. The analysis of characteristics of materials allows one to specify their phase changes caused by external influences and to investigate the magnetic properties. During the consideration of magnetic properties of thin films such material characteristics as the coercive force and saturation magnetization, and their dependence on the technology of deposition conditions (oxygen pressure, the deposition rate, temperature), the film thickness, the percentage composition of its constituent elements, heat treatment (annealing) and film microstructure, were studied. Materials and Methods: Analysis of multiferroic material properties in order to clarify the electrical characteristics and physical properties was conducted on the basis of iron-containing, cobalt-containing, barium-containing and rare earth transition metal alloys, that have helped to clarify the possibility and conditions of material phase transitions, their magnetic susceptibility to external magnetic and electromagnetic fields and to develop technological equipment for study of sample magnetic properties while subjecting by external electromagnetic fields. It is shown that phase transitions in multiferroic materials used in thinfilm samples are characterized by two types of allotropy, manifested in the presence of e-phase with a hexagonal dense packing structure and a-phase face-centered cubic structure. Their relationship and the transition between them depend on the purity, processing conditions and cooling rate. The paper discusses the properties of iron-containing, cobalt-containing, barium-containing, amorphous thin-film layers of the recording systems and magnetic properties of cobalt-chromium thin-film layers. Conclusion: Analysis of the results allows one to make a conclusion about the possibility of creating equipment with a magnetic-controlled system for the creation of magnetic fields, the intensity of which exceeds the value of the coercive force of multiferroic materials used in existing data carriers. Experimental confirmation of phase transitions in the presented materials is a prerequisite for the development of devices for the urgent destruction of information from electronic data carriers.