From an interdisciplinary viewpoint, the fine particle magnetism brings about interest on some areas that study systems which present natural dispersions of magnetic crystallites, such as some animals or geological elements. Also, one can artificially produce materials of potential application in chemistry and engineering (magnetic fluids, magnetic paints, catalysis, magneto-rheological fluids), facts that make the study of nanostructured magnetic materials being of broad utility. The interest in these systems was renewed with the discovery of the giant magnetoresistance phenomenon in the beginning of the nineties, and, since then, several novel phenomena have been discovered, and subsequently calling the attention of the international scientific community. The inherent complexity of the granular systems, allied with the difficulty to study a single isolated magnetic particle, has become a challenge that has been continuously surpassed through novel theoretical models, computer simulations, and development of new experimental techniques. In the talk, a general perspective of the magnetic investigations in granular magnetic systems constituted by ultra-fine particles embedded in a non-magnetic matrix. An emphasis will be given to the technological implications of such studies, and the main difficulties faced nowadays by the research teams that work in the field of magnetic recording, for example. To help with the understanding of the discussed topics, several basic principles related to the magnetism of nanocrystalline particle will be revised, such as the Stoner-Wohlfarth model and the concept of superparamagnetism. The phenomena of Giant magnetoresistance and giant Hall effect will be commented and discussed. Finally, recent results from the literature will be shown in order to illustrate the basic concepts and show some questions that are still unanswered in this fascinating area of magnetism and condensed matter Physics. B
Viernes 7 de agosto de 2020, 9am COL
Webex
Inscripciones: https://is.gd/7RoisW
