Publications by authors named "Luis Alfredo Rodriguez"
Gold nanostructures (AuNSs) were used to fabricate surface-enhanced Raman spectroscopy (SERS) substrates. These AuNSs were produced using the solid-state dewetting method from thin films. The fragmentation process was studied at 300 °C, with durations of thermal treatment of 1, 3, 6, and 12 h.
View Article and Find Full Text PDFIn this work, a bibliometric study was carried out to perform a scientific and technological analysis of exchange-spring magnets, an alternative permanent magnet synthesized by reducing or eliminating the use of critical raw materials, such as rare earths. The bibliometric analysis utilized the Scopus database, Orbit-Intellixir, VOSviewer, Orbit-Intelligence and Loglet Lab 4 software for maturity analysis, keyword network representations, charts and graphs for scientific articles and/or patents. A special analysis was performed on nanocomposite and thin-films systems based on Nd-Fe-B, SmCo and Mn-Al-C alloys, either mixed or layered with a soft magnetic phase, where relevant information on their magnetic parameters was compilated in tables, highlighting the nanostructured systems that have been exhibited the best permanent magnet properties.
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- The MnAlC alloy, which doesn't contain rare earth materials, is being recognized as a promising and affordable option for permanent magnets due to its high anisotropy field, saturation magnetization, and Curie temperature.
- A simple fabrication method was developed to produce a bulk -MnAlC magnet, utilizing electric arc-melting and a two-step heat treatment to achieve a pure -MnAlC ingot.
- The resulting -MnAlC showed improved magnetic properties with a remanent magnetization of 42 Am/kg and a maximum energy product of 6.07 kJ/m, surpassing previous results and demonstrating high-quality ferromagnetic behavior.
High-purity TiO and CuO powders were synthesized by the Pechini method, an inexpensive and easy-to-implement procedure to synthetize metal oxides. The variables of synthesis were the ethylene glycol:citric acid molar ratio and the pH. High reproducibility of the anatase and tenorite phase was obtained for all synthesis routes.
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- Researchers conducted a detailed analysis of the magnetic properties of Co-rich CoNi nanowires using electron holography, focusing on their structural features at the nanoscale.
- The nanowires exhibited both face-centered cubic (fcc) and hexagonal close packed (hcp) crystal structures, and the magnetic configurations showed significant complexity, with distinct vortex formations and axial orientations linked to these structures.
- Local variations in chemical composition influenced the crystalline orientations and magnetic behaviors, and micromagnetic simulations helped clarify the relationship between these structural differences and the observed magnetic states.
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- Magnetic nanostructures have the potential to surpass silicon's limitations in hybrid CMOS technology by improving their magnetization characterization.
- Magnetic force microscopy (MFM) struggles with balancing resolution and sensitivity due to probe-sample interactions, but a new method utilizing a pinned magnetic domain wall in a V-shaped nanostructure can enhance both.
- This study demonstrates that by controlling the magnetic states of the domain wall probes through electron holography and simulations, researchers can effectively switch between low and high stray field intensities for improved measurements.
We present a comprehensive method for visualisation and quantification of the magnetic stray field of magnetic force microscopy (MFM) probes, applied to the particular case of custom-made multi-layered probes with controllable high/low magnetic moment states. The probes consist of two decoupled magnetic layers separated by a non-magnetic interlayer, which results in four stable magnetic states: ±ferromagnetic (FM) and ±antiferromagnetic (A-FM). Direct visualisation of the stray field surrounding the probe apex using electron holography convincingly demonstrates a striking difference in the spatial distribution and strength of the magnetic flux in FM and A-FM states.
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- The study focuses on understanding the magnetic behavior of FeCoCu nanowires that have variable diameters, which is crucial for manipulating magnetic domain wall movement using magnetic fields and current pulses.
- By utilizing advanced techniques like electron holography and magnetic force microscopy, researchers detail how the varying diameter creates vortex-like structures and magnetic charges that alter magnetization alignment within the wires.
- This research aims to establish foundational knowledge for future studies on magnetization reversal, helping in the design of nanowires that optimize domain wall movement.
Nanoenergetic materials are beginning to play an important role in part because they are being considered as energetic components for materials, chemical, and biochemical communities (e.g., microthermal sources, microactuators, in situ welding and soldering, local enhancement of chemical reactions, nanosterilization, and controlled cell apoptosis) and because their fabrication/synthesis raises fundamental challenges that are pushing the engineering and scientific frontiers.
View Article and Find Full Text PDFWe have successfully grown ultrasmall cobalt nanostructures (lateral size below 30 nm) by optimization of the growth conditions using focused electron-beam-induced deposition techniques. This direct-write nanolithography technique is thus shown to produce unprecedented resolution in the growth of magnetic nanostructures. The challenging magnetic characterization of such small structures is here carried out by means of electron holography techniques.
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