Browsing by Author "Velasquez, Ever A."
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- ItemComplex magnetic states in Ni/Fe bi-segmented nanorods(2015) Mejía López, José Félix; Velasquez, Ever A.; Lopez-Moreno, S.; Mazo-Zuluaga, J.
- ItemConvoluted 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, JoseDue 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.
- ItemFe/Ni core/shell nanowires and nanorods: A combined First-Principles and atomistic simulation study(2017) Velasquez, Ever A.; Lopez Moreno, S.; Mazo-Zuluaga, J.; Mejía López, José Félix
- ItemFinite-length Fe nanowire arrays: the effects of magnetic anisotropy energy, dipolar interaction and system size on their magnetic properties(2017) Ochoa, A.; Mejía López, José Félix; Velasquez, Ever A.; Mazo, J.
- ItemHydrogen induced AFM to FM magnetic transition in epsilon-FeHx(2020) Leon, A; Velasquez, Ever A.; Torres, FJ; Mejía López, José Félix; Vargas, P
- ItemIndependent Anti-Angiogenic Capacities of Coagulation Factors X and Xa(2014) Lange, S.; Gonzalez, I.; Pinto, M.; Arce, M.; Valenzuela Bassi, Rodrigo Andrés; Aranda, E.; Elliot, M.; Alvarez, M.; Henriquez, S.; Velasquez, Ever A.; Orge, F.; Oliva, B.; Gonzalez, P.; Villalón, Manuel J.; Cautivo Reyes, Kelly Margarita; Kalergis Parra, Alexis Mikes; Pereira, K.; Mendoza, C.; Saez, C.; Kato Cardemil, Sumie Rode; Cuello F., Mauricio; Parborell, F.; Irusta, G.; Palma, V.; Allende, M.; Owen, Gareth Ivor
- ItemMagnetic effects of interstitial hydrogen in nickel(2017) Leon, A.; Velasquez, Ever A.; Mazo, J.; Mejía López, José Félix; Florez, J.; Vargas, P.
- ItemOrnstein-Zernike correlations and magnetic ordering in nanostructures(2014) Velasquez, Ever A.; Mejía López, José Félix
- ItemSize dependence study of the ordering temperature in the Fast Monte Carlo method(2013) Velasquez, Ever A.; Mejía López, José Félix
- ItemThermal gradients for the stabilization of a single domain wall in magnetic nanowires(2018) Mejía López, José Félix; Velasquez, Ever A.; Mazo-Zuluaga, J.; Altbir, D.
- ItemTuning Magnetic Order in CrI3 Bilayers via Moire Patterns(2022) Leon, Andrea M.; Velasquez, Ever A.; Caro-Lopera, Francisco; Mejia-Lopez, JoseCommensurable twisted bilayers can drastically change the magnetic properties of chromium trihalide layered compounds, which opens novel opportunities for tuning magnetic states through layer rotations. Here, a mathematical approach to obtain moire patterns in twisted hexagonal bilayers by performing a certain commensurable rotation theta over one layer is presented. To test the approach, moire structures with theta=21.79 degrees and 32.20 degrees in the phases R (3) over bar and C2/m of CrI3 are obtained via the related methodology. For comparison purposes, a non-shifted CrI3 structure is also considered. Electronic and magnetic properties of the so-obtained systems are computed by ab initio methodologies. Results show the presence of rotation-angle-dependent magnetic configurations and steep modifications of the dispersion bands due to variations in the nearest and next nearest distances among layers of Cr atoms. Modifications obtained from these commensurable rotations are discussed on the basis of competition among different energy contributions due to changes in the atomic neighborhood.
- ItemUnderstanding the loss of electrochemical activity of nanosized limn2o4 particles: a combined experimental and ab initio DFT study(2018) Velasquez, Ever A.; Silva, Daiane P. B.; Falqueto, Juliana B.; Mejía López, José Félix; Bocchi, Nerilso; del Rio, Rodrigo; Mazo-Zuluaga, Johan; Rocha-Filho, Romeu C.; Biaggio, Sonia R.