Ultrafast Spin Dynamics of Next-Generation Nanomagnetic Technologies

Over the past 50 years, our society has experienced a technological revolution that has fundamentally changed the way our world operates. At the heart of this revolution are the computational building blocks that work together to perform mathematical operations and save the results. For many years, the size of the computing elements (e.g. transistors) has been consistently shrunk so that more devices could fit on a chip in order to increase computational power. To provide adequate data storage for the ever-increasing number of computations, the hard-disk drive (HDD) was developed in the 1980s and would forever revolutionize the landscape of memory storage. Today, HDDs still account for a vast majority of the data stored worldwide. These devices store information using the magnetization of nanoscopic domains in a granular magnetic film, however, in recent years it has become increasingly challenging to reduce the size of the domains further without fundamentally changing the HDD. Indeed, the latest iteration of this technology has incorporated lasers into the devices to leverage multiple degrees of freedom in order to achieve higher bit densities. This example highlights a common trend for all next-generation computational technologies – the strong coupling between distinct physical systems must be utilized to sustain the improvements our society has become accustomed to. In order to realize this lofty goal, the physics of nanoscale systems must be well understood to predict their behavior. As our collective understanding of this field continues to flourish, novel effects are found that open doors to previously unimaginable technologies that may usher in a revolution of their own. Indeed, there are both technological and fundamental interests to study nanostructured devices.In this thesis, the time-resolved magneto-optic Kerr effect (TR-MOKE) will be utilized to probe the ultrafast spin dynamics of magnetic films, multilayer heterostructures, and nanostructures. Our experimental observations of these systems are evaluated by combining various field of science and technology, including (but not limited to) condensed matter theory, signal processing, and optics. In doing so, we seek to fully explain the data and to enrich the understanding of these underexplored systems to inform the rational design of next-generation technologies. Specifically, a great deal of attention will be paid to emergent nanotechnologies that leverage the coupling between the magnetic system and either the electronic or mechanical properties of the device to tailor the performance. In this work, a novel method to restore the intrinsic magnetization dynamics and simultaneously improve the magneto-optical response of dense nanomagnet arrays will be presented. Then, our work on the spin dynamics of isolated nanomagnets resonantly excited by microwave-frequency acoustic waves will be reviewed, wherein we show for the first time that the coupling efficiency is ultimately limited by the damping of the magnetic system. In addition, the role of the nanomagnet geometry and the acoustic wavelength will be fully explored to determine critical parameters that govern the dynamic magneto-elastic resonance. Lastly, the development of an optical system to study the interplay between ultrafast all-optical switching and surface acoustic waves will be reviewed

Strongly coupled magnon-phonon dynamics in a single nanomagnet.

Polaritons are widely investigated quasiparticles with fundamental and technological significance due to their unique properties. They have been studied most extensively in semiconductors when photons interact with various elementary excitations. However, other strongly coupled excitations demonstrate similar dynamics. Specifically, when magnon and phonon modes are coupled, a hybridized magnon-phonon quasiparticle can form. Here, we report on the direct observation of coupled magnon-phonon dynamics within a single thin nickel nanomagnet. We develop an analytic description to model the dynamics in two dimensions, enabling us to isolate the parameters influencing the frequency splitting. Furthermore, we demonstrate tuning of the magnon-phonon interaction into the strong coupling regime via the orientation of the applied magnetic field

Estudios globales sobre el cadmio en relación con Theobroma cacao: Un análisis bibliométrico desde Scopus (1996 -2020)

The maximum cadmium tolerance standards were established by the European Union in 2014, for the importation of cocoa-based products, causing concern in the countries. Global studies on Theobroma cacao research related to cadmium activity in the atmosphere were analyzed. Bibliometric analyses in R and VOSviewer programs were used to examine 64 documents published in the Scopus database according to keywords. We identified 811 keywords in the co-occurrence of terms, 5 thematic groups in the bibliographic coupling, 20 institutions as most important affiliations, 20 countries of origin of corresponding authors, 112 institutions in co-authorship network of which 5 are in primary documents, and two groups in thematic similarity in co-citation of documents. The United States leads the scientific production with 11 papers, followed by Colombia (8) and Ecuador (7). In 1996, the first scientific article was registered for the network, with increases of up to 11 publications by 2020. In conclusion, the need to strengthen and create more research networks between countries, institutions, authors, and co-authors is evident. It is hoped that the results will allow a comprehensive unraveling of the cadmium-cocoa research trajectory, while at the same time yielding new prospective research.En el año 2014, la Unión Europea impuso estándares máximos de tolerancia en cadmio, para la importación de productos a base de cacao, causando preocupación en los países. Se analizó estudios globales referidos a investigaciones en Theobroma cacao, relacionados con la actividad del cadmio en la atmósfera. Se utilizaron análisis bibliométricos en los programas R y VOSviewer, para examinar 64 documentos publicados en la base de datos Scopus según palabras clave. Se identificaron 811 palabras clave en coocurrencias de términos, 5 grupos temáticos en acoplamiento bibliográfico, 20 instituciones como afiliaciones más importantes, 20 países de procedencia de autores corresponsales, 112 instituciones en red de coautoría de los cuales 5 están en documentos primarios, y dos grupos en similaridad temática en co-citación de documentos. Estados Unidos lidera la producción científica con 11 documentos, seguido de Colombia (8) y Ecuador (7). En 1996 se registró el primer artículo científico para la red, con incrementos de hasta 11 publicaciones al 2020. En conclusión, se evidencia la necesidad de fortalecer y crear más redes de investigaciones entre países, instituciones, autores y coautores. Se espera que los resultados permitan desentrañar de manera integral la trayectoria de investigaciones cadmio-cacao, al tiempo que arrojen nuevas investigaciones prospectivas

Estudios globales sobre el cadmio en relación con Theobroma cacao: Un análisis bibliométrico desde Scopus (1996 -2020)

En el año 2014, la Unión Europea impuso estándares máximos de tolerancia en cadmio, para la importación de productos a base de cacao, causando preocupación en los países. Se analizó estudios globales referidos a investigaciones en Theobroma cacao, relacionados con la actividad del cadmio en la atmósfera. Se utilizaron análisis bibliométricos en los programas R y VOSviewer, para examinar 64 documentos publicados en la base de datos Scopus según palabras clave. Se identificaron 811 palabras clave en coocurrencias de términos, 5 grupos temáticos en acoplamiento bibliográfico, 20 instituciones como afiliaciones más importantes, 20 países de procedencia de autores corresponsales, 112 instituciones en red de coautoría de los cuales 5 están en documentos primarios, y dos grupos en similaridad temática en co-citación de documentos. Estados Unidos lidera la producción científica con 11 documentos, seguido de Colombia (8) y Ecuador (7). En 1996 se registró el primer artículo científico para la red, con incrementos de hasta 11 publicaciones al 2020. En conclusión, se evidencia la necesidad de fortalecer y crear más redes de investigaciones entre países, instituciones, autores y coautores. Se espera que los resultados permitan desentrañar de manera integral la trayectoria de investigaciones cadmio-cacao, al tiempo que arrojen nuevas investigaciones prospectivas

Strongly coupled magnon-phonon dynamics in a single nanomagnet.

Polaritons are widely investigated quasiparticles with fundamental and technological significance due to their unique properties. They have been studied most extensively in semiconductors when photons interact with various elementary excitations. However, other strongly coupled excitations demonstrate similar dynamics. Specifically, when magnon and phonon modes are coupled, a hybridized magnon-phonon quasiparticle can form. Here, we report on the direct observation of coupled magnon-phonon dynamics within a single thin nickel nanomagnet. We develop an analytic description to model the dynamics in two dimensions, enabling us to isolate the parameters influencing the frequency splitting. Furthermore, we demonstrate tuning of the magnon-phonon interaction into the strong coupling regime via the orientation of the applied magnetic field