Estudio de la ferrita MgFe2O4 mediante cálculos ab-initio: del volumen a la superficie
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Date
2024
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Universidad Nacional de Trujillo
Abstract
Las ferritas de espinela de AFe2O4 (A = Ni, Cu, Mn, Mg, Co o Zn, etc.) siguen siendo uno de los materiales funcionales más interesantes de las últimas décadas, debido a sus incomparables propiedades magnéticas, eléctricas y dieléctricas. Estas propiedades eléctricas y magnéticas tienen una amplia gama de aplicaciones en circuitos de radiofrecuencia de alta y muy alta frecuencia, núcleos de transformadores, dispositivos de almacenamiento de datos, alta velocidad de lectura/escritura, entre otros. Entre las diferentes ferritas de espinela, la ferrita de magnesio (MgFe2O4), un material semiconductor magnético suave de tipo n que posee una estructura de espinela inversa, es una de las más destacadas. En este trabajo se realizó un estudio ab initio de las propiedades estructurales, electrónicas, magnéticas e hiperfinas del MgFe2O4 en el marco de la Teoría del Funcional de Densidad (DFT) utilizando los métodos FP-LAPW+LO y Pseudopotencial, empleando el método Generalizado. Aproximación de gradiente (GGA) y GGA+U para el plazo potencial y el intercambio. Los cálculos muestran que la estructura de equilibrio corresponde a una configuración invertida y antiferromagnética, en la que los momentos magnéticos de los átomos de Fe en los sitios A están ordenados ferromagnéticamente entre sí y antiferromagnéticamente con respecto al Fe en la subred de sitios B, mientras que los átomos de magnesio no se polarizan. La excelente concordancia entre los cálculos teóricos y los resultados experimentales reportados en la literatura respalda la distribución de cationes y la configuración magnética de menor energía obtenida para MgFe2O4. A partir de estos resultados se comenzó a estudiar la estabilidad de las diferentes superficies de esta ferrita considerando diferentes acabados superficiales, teniendo en cuenta en todos los casos las reconstrucciones estructurales. Los resultados que presentamos predicen que la superficie más estable está invertida, exponiendo átomos de Fe, Mg y O. Esta superficie presenta un momento magnético neto, dando lugar a un sistema ferrimagnético.
Abstract Spinel ferrites of AFe2O4 (A = Ni, Cu, Mn, Mg, Co or Zn, etc.) have remained one of the most interesting functional materials in recent decades, because of their unparalleled magnetic, electric and dielectric properties. These electrical and magnetic properties have a wide range of applications in high and very high frequency radio frequency circuits, transformer cores, data storage devices, high read/write speed, among others.Among different spinel ferrites, magnesium ferrite (MgFe2O4), a soft magnetic n-type semiconducting material possessing inverse spinel structure is one of the most prominent. In this work, an ab initio study of the structural, electronic, magnetic and hyperfine properties of MgFe2O4 was carried out within the framework of Density Functional Theory (DFT) using the FP-LAPW+LO and Pseudopotential methods, employing the Generalized Gradient Approximation (GGA) and the GGA+U for the potential term and exchange. The calculations show that the equilibrium structure corresponds to an inverted and antiferromagnetic configuration, in which the magnetic moments of the Fe atoms in the A sites are ordered ferromagnetically with each other and antiferromagnetically with respect to the Fe in the sub-network of B sites, while the Magnesium atoms do not polarize.The excellent agreement between theoretical calculations and experimental results reported in the literature supports the cation distribution and the lowest energy magnetic configuration obtained for MgFe2O4. From these results, the stability of the different surfaces of this ferrite began to be studied considering different surface finishes, taking into account structural reconstructions in all cases. The results we present predict that the most stable surface is inverted, exposing Fe, Mg, and O atoms. This surface presents a net magnetic moment, giving rise to a ferrimagnetic system
Abstract Spinel ferrites of AFe2O4 (A = Ni, Cu, Mn, Mg, Co or Zn, etc.) have remained one of the most interesting functional materials in recent decades, because of their unparalleled magnetic, electric and dielectric properties. These electrical and magnetic properties have a wide range of applications in high and very high frequency radio frequency circuits, transformer cores, data storage devices, high read/write speed, among others.Among different spinel ferrites, magnesium ferrite (MgFe2O4), a soft magnetic n-type semiconducting material possessing inverse spinel structure is one of the most prominent. In this work, an ab initio study of the structural, electronic, magnetic and hyperfine properties of MgFe2O4 was carried out within the framework of Density Functional Theory (DFT) using the FP-LAPW+LO and Pseudopotential methods, employing the Generalized Gradient Approximation (GGA) and the GGA+U for the potential term and exchange. The calculations show that the equilibrium structure corresponds to an inverted and antiferromagnetic configuration, in which the magnetic moments of the Fe atoms in the A sites are ordered ferromagnetically with each other and antiferromagnetically with respect to the Fe in the sub-network of B sites, while the Magnesium atoms do not polarize.The excellent agreement between theoretical calculations and experimental results reported in the literature supports the cation distribution and the lowest energy magnetic configuration obtained for MgFe2O4. From these results, the stability of the different surfaces of this ferrite began to be studied considering different surface finishes, taking into account structural reconstructions in all cases. The results we present predict that the most stable surface is inverted, exposing Fe, Mg, and O atoms. This surface presents a net magnetic moment, giving rise to a ferrimagnetic system
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Keywords
Teoría de la Funcional Densidad, Ferrita de Magnesio, Método FP-LAPW y método Pseudopotenciales