Guzmán Arellano, Robert Mikhail (2010) Transporte de carga y espín en grafeno. Maestría en Ciencias Físicas, Universidad Nacional de Cuyo, Instituto Balseiro.
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Resumen en español
En este trabajo se exponen inicialmente las herramientas usadas en el estudio de las cintas de grafeno con condiciones de borde tipo zig-zag (ZGNR), siendo estos cálculos analíticos de enlace fuerte y métodos recursivos de las funciones de Green. Usamos ZGNR porque tienen estados electrónicos localizados en los bordes de la cinta (estados de borde). Luego se analizaron las propiedades de las bandas de energía, densidad de estados y transmisión en ZGNR. Después adicionamos las interacciones electrón-electrón usando la interacción local de Hubbard en campo medio. Los resultados indican que los estados de borde permiten que el flujo de carga eléctrica esté separado en dos caminos dejando un agujero de carga en medio de la cinta, concluyendo que los ZGNR pueden ser usados en interferometría, este resultado es la motivación del estudio del transporte en ZGNR. Luego estudiamos las distintas fases magnéticas en ZGNR, calculando la energía del estado fundamental del ZGNR y su distribución electrónica en distintas fases a distintos dopajes electrónicos. En este punto concluimos que la ocupación parcial de los estados de borde es responsable de las distintas fases magnéticas. Por ultimo, estudiamos el transporte eléctrico a través de pozos de potencial, se encontró que el grafeno inmerso en un pozo de potencial modifica su distribución electrónica en carga y espín, permitiendo la existencia de regiones con orden magnético, formándose paredes de dominio. Estas distribuciones generan cambios bruscos en la distribución electrónica, permitiendo distintos comportamientos en el transporte eléctrico para cada espín.
Resumen en inglés
In this work, in the beginning we expose the tools used in the study of graphene nanoribbons with conditions of zigzag shaped border (ZGNR), these are analytical calculations of tight binding and recursive methods of the Green functions. We used ZGNR because they have electronic states located in the nanoribbon borders (edge states). Then, we analyzed the properties of the bands of energy, density of states and transmission in ZGNR. After that, we included the electron-electron interactions using the Hubbard local interaction in the mean field. The results indicate that the edge states allow that the electric charge flux is separated in two ways leaving a hole of charge in the middle of the nanoribbon, and we conclude that the ZGNR may be used in interpherometry; this result is the motivation of this study of the transport in ZGNR. Afterwards, we studied the different magnetic phases in ZGNR, calculating the energy of the fundamental state of the ZGNR and its electronic distribution in different phases to different electronic dopings. In this point we conclude that the partial occupation of the edge states is responsible of the different magnetic phases. Finally, we study the electric transport by means of potential wells.We found that the graphene immerse in a potential well modifies its electronic distribution in charge and spin, allowing the existence of regions with magnetic order, forming domain walls. These distributions generate strong changes in the electronic distribution, allowing different behaviors in the electric transport for each spin.
| Tipo de objeto: | Tesis (Maestría en Ciencias Físicas) |
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| Palabras Clave: | Espín; Spin; Densidad electrónica; Electron density; Magnetismo; Magnetism; Antiferromagnetismo; Antiferromagnetism; Cintas de grafeno |
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| Materias: | Física > Electromagnetismo Física > Física de materiales |
| Divisiones: | Investigación y aplicaciones no nucleares > Física > Teoría de sólidos |
| Código ID: | 131 |
| Depositado Por: | Samanta Tello |
| Depositado En: | 05 Jul 2010 09:47 |
| Última Modificación: | 05 Jul 2010 09:47 |
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