Browsing by Author "Mazo-Zuluaga, Johann"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Convoluted Magnetoresistance and Magnetic Reversal Processes in Ni-Fe Segmented Cylindrical Nanodots with Tunable Size and Composition for Technological Applications
    (2023) Velasquez, Ever A.; Mazo-Zuluaga, Johann; Mejia-Lopez, Jose
    Due to their unique properties, bi-segmented systems are currently used in several technological applications such as sensing devices, high density magnetic data storage systems, spintronics and microelectromechanical components, among others. In this study, the magnetoresistance and magnetic properties of Ni-Fe bi-segmented cylindrical nanodots in a broad range of diameters and heights are discussed. The power of the First Principles approach, as considered in the density functional theory formulation, is used to study the structural and magnetic relaxation effects, and atomistic simulations, through the Fast Monte Carlo methodology, are employed to explore the magnetoresistance and magnetic behaviors of these systems. By means of the magnetic hysteresis and magnetoresistance signals, convoluted magnetization reversal schemes are discussed. These effects take place depending on the size of the Ni and Fe components as a result of the interplay among exchange interactions and size and shape effects induced by dipolar interactions. Since size has become an experimental controllable parameter, due to the enriched phenomena, the effects discussed in these bi-component systems are useful for the design and production of devices for technological applications with relevance beyond the observed in the more restricted single component systems.
  • No Thumbnail Available
    Item
    Dynamical Stability and Physical Properties of Fe Dihalide Nanowires
    (2023) Mejia-Lopez, Jose; Lopez-Moreno, Sinhue; Mazo-Zuluaga, Johann; Romero-Vazquez, Pricila Betbirai; Moran-Lopez, Jose Luis
    An extensive first-principles and atomistic Monte Carlo study on isolated FeX2 (X = F, Cl, Br, I) nanowires is presented. The structural properties of the FeX2 chains are determined and compared with their bulk structures. The results indicate that in the lowest energy configuration, the wires crystalize in a system that belongs to the space group P42/mmc (No. 131, Z = 2, point group D-4h(9)), with antiferromagnetic arrangement. The stability is determined by calculating the phonon frequencies in the whole Brillouin zone within the supercell approach. The relative stability of the periodic chains is also determined by calculating the elastic properties and comparing them with bulk cases. The band structure, the density of states, the magnetic properties, the anisotropy energy, and topological analysis, performed with the Quantum Theory of Atoms in Molecules approach, are also reported and discussed. The results support the idea that these FeX2 nanowire systems are promising materials for practical applications, like lithium-ion batteries.