Universidad del Norte, Colombia

About: Universidad del Norte, Colombia is a education organization based out in Barranquilla, Colombia. It is known for research contribution in the topics: Population & Context (language use). The organization has 3562 authors who have published 4355 publications receiving 37861 citations. The organization is also known as: University of the North, Colombia & Uninorte.

Efficient Electrical Spin Splitter Based on Nonrelativistic Collinear Antiferromagnetism.

Abstract: Spin-current generation by electrical means is among the core phenomena driving the field of spintronics. Using ab initio calculations we show that a room-temperature metallic collinear antiferromagnet ${\mathrm{RuO}}_{2}$ allows for highly efficient spin-current generation, arising from anisotropically spin-split bands with conserved up and down spins along the N\'eel vector axis. The zero net moment antiferromagnet acts as an electrical spin splitter with a 34\ifmmode^\circ\else\textdegree\fi{} propagation angle between spin-up and spin-down currents. The corresponding spin conductivity is a factor of 3 larger than the record value from a survey of 20 000 nonmagnetic spin-Hall materials. We propose a versatile spin-splitter-torque concept circumventing limitations of spin-transfer and spin-orbit torques in present magnetic memory devices.

Single-Crystal Silicon Carbide: A Biocompatible and Hemocompatible Semiconductor for Advanced Biomedical Applications

Abstract: Crystalline silicon carbide (SiC) and silicon (Si) biocompatibility was evaluated in vitro by directly culturing three skin and connective tissue cell lines, two immortalized neural cell lines, and platelet-rich plasma (PRP) on these semiconducting substrates. The in vivo biocompatibility was then evaluated via implantation of 3C-SiC and Si shanks into a C57/BL6 wild type mouse. The in vivo results, while preliminary, were outstanding with Si being almost completely enveloped with activated microglia and astrocytes, indicating a severe immune system response, while the 3C-SiC film was virtually untouched. The in vitro experiments were performed specifically for the three adopted SiC polytypes, namely 3C-, 4H- and 6H-SiC, and the results were compared to those obtained for Si crystals. Cell proliferation and adhesion quality were studied using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assays and fluorescent microscopy. The neural cells were studied via atomic force microscopy (AFM) which was used to quantify filopodia and lamellipodia extensions on the surface of the tested materials. Fluorescent microscopy was used to assess platelet adhesion to the semiconductor surfaces where significantly lower values of platelet adhesion to 3C-SiC was observed compared to Si. The reported results show good indicators that SiC is indeed a more biocompatible substrate than Si. While there were some differences among the degree of biocompatibility of the various SiC polytypes tested, SiC appears to be a highly biocompatible material in vitro that is also somewhat hemocompatible. This extremely intriguing result appears to put SiC into a unique class of materials that is both bio- and hemo-compatible and is, to the best of our knowledge, the only semiconductor with this property.

Electrical switching of perpendicular magnetization in a single ferromagnetic layer

Abstract: We report on the efficient spin-orbit torque (SOT) switching in a single ferromagnetic layer induced by a new type of inversion asymmetry, the composition gradient. The SOT of 6- to 60-nm epitaxial FePt thin films with a $L{1}_{0}$ phase is investigated. The magnetization of the FePt single layer can be reversibly switched by applying electrical current with a moderate current density. Different from previously reported SOTs which either decreases with or does not change with the film thickness, the SOT in FePt increases with the film thickness. We found the SOT in FePt can be attributed to the composition gradient along the film normal direction. A linear correlation between the SOT and the composition gradient is observed. This Rapid Communication introduces a platform to engineer large SOTs for lower-power spintronics.

An integrated method to plan, structure and validate a business strategy using fuzzy DEMATEL and the balanced scorecard

Abstract: Strategy literature has mainly focused on conceptual tools to support stages of the planning and structuring of the strategy within the context of a Balanced Scorecard (BSC). Recently, quantitative tools based on multi-criteria decision-making methods (MCDM) have received more attention; however, studies still have limitations. Such is the case of Fuzzy DEMATEL, which has been proposed in the literature, but not integrated within the whole process of strategy formulation. In addition, studies have presented weaknesses by not considering, for instance, the logical structure of a strategy map. Hence, the main objective of this study is to propose the development of a method that supports the overall process of planning, structuring and validating a business unit strategy while overcoming the limitations of previous works, considering the subjectivity of decision-making in the construction of strategy maps. To fulfil these purposes, this study proposes an extension of the work of Lopez-Ospina et al. (2017) entitled “A method for designing strategy maps using DEMATEL and linear programming”, by integrating fuzzy logic and traditional, conceptual and qualitative tools to support the diagnosis and strategy design. The significant contributions of this work is that it overcomes limitations of previous methods by providing: (1) a logic structure of strategy maps; (2) integration of subjectivity within the overall formulation process of the strategy; (3) selection of the most important relationships between strategy objectives to explain efficiently, functionally, and easily the route map of a strategy; and (4) integration of traditional qualitative tools with quantitative tools, making the process robust and holistic. The proposed method was applied to an Official Banking business unit of a Colombian bank, where expert judgment for strategy formulation helps to test the effect of the methodological design.