Desenvolvimento de semicondutores magnéticos diluídos à base de ZnO dopado com Ni obtidos por reação de combustão como materiais de Spintrônica

Abstract

Diffused magnetic semiconductors (DMS) are characterized by the properties of a semiconductor together with ferromagnetism, introduced by the addition of doping ions that have a non-zero magnetic moment. The idea of the application of the SMDs came with the advent of spintronics and the possibility of raising the capacity and power and processing, data recording density and miniaturizing our electronic, optical and magnetic devices to levels beyond current ones. For this, the DMS must be manufactured, because there are no naturally ferromagnetic semiconductors. Together with the domain of spin control and detection techniques required in spintronics, obtaining DMS is also a decisive factor in the consolidation of this technology. The route of synthesis is a factor that directly affects the final properties of a material, so that systems of similar compositions may have distinct properties, only with change in the obtaining process. In this work, a SMD based on zinc oxide (ZnO), doped with Ni2+ ions at concentrations of 0.08 and 0.15 mols, was synthesized by combustion reaction. The second part of the work consists of sintering the systems produced at temperatures of 600 and 800 ° C for one hour. The material was characterized by X-ray Diffraction, Vibrant Sample Magnetometry (VSM) and Uv-Vis Spectroscopy. The formation of the ZnO semiconductor phase was observed, as well as a second phase of nickel oxide and a solid solution of the nickel and zinc oxides, before and after sintering, respectively. The presence of these phases is detrimental to the magnetic properties as a consequence of their antiferromagnetic characteristics. Nevertheless, the studied systems present weak ferromagnetism, consistent with many results reported in the literature. The energy gaps of the systems were studied by the Uv-Vis technique, as well as the dilution of Ni2+ ions in the lattice. The origin of ferromagnetism is discussed by presenting several points of view on the subject in the literature, and taking into account the data obtained in this work.