Multipoles, Magnetic charges and chiral properties in antiferromagnetic materials inferred from resonant X-Ray diffraction
type: CreativeWork
description: In the last decades, the interesting features behind the exotic orderings of materials have attracted the attention of many scientists. This new physics can be related to the magnetic and charge multipoles defined by a few electrons around the atomic core in the valence states. The uses of x-rays and neutrons techniques, due to the huge development of large facilities as synchrotrons and spallation sources, have revealed many of these behaviours. In the case of synchrotron sources, photon beams have high brightness, high tunability and good degree of polarization, which together with the development of new experimental techniques have been helpful in the characterization of new functional materials making valuable observations. Resonant Elastic x-ray Scattering (REXS), in particular using polarization analysis, has shown to be an extremely sensitive tool for determining the charge and magnetic degrees of freedom of multiferroic, superconducting or other kind of strongly correlated materials; helping whereas other techniques such as neutron probes or non-resonant x-rays scattering are not able to obtain relevant information. Conventionally, REXS experiments are performed at space group forbidden reflections, where high order contributions as Thomson scattering are not allowed. The data gathered at these weak Bragg reflections, due to space group symmetry rules, can be treated using an atomic model, which has the virtue of being used as a common platform for the analysis of x-ray and neutron diffraction experiments. In this PhD work, three different antiferromagnetic materials with magnetic ions located in threefold symmetry (3) positions have been investigated in detail by means of REXS. Neptunium Dioxide (NpO2), where an enigmatic low-temperature ordering state shows interesting physical features, similar to the one observed in UO2, that relates its crystal field, the super-exchange interactions and electron¿phonon coupling. Previous works from different groups have…
abstract: In the last decades, the interesting features behind the exotic orderings of materials have attracted the attention of many scientists. This new physics can be related to the magnetic and charge multipoles defined by a few electrons around the atomic core in the valence states. The uses of x-rays and neutrons techniques, due to the huge development of large facilities as synchrotrons and spallation sources, have revealed many of these behaviours. In the case of synchrotron sources, photon beams have high brightness, high tunability and good degree of polarization, which together with the development of new experimental techniques have been helpful in the characterization of new functional materials making valuable observations. Resonant Elastic x-ray Scattering (REXS), in particular using polarization analysis, has shown to be an extremely sensitive tool for determining the charge and magnetic degrees of freedom of multiferroic, superconducting or other kind of strongly correlated materials; helping whereas other techniques such as neutron probes or non-resonant x-rays scattering are not able to obtain relevant information. Conventionally, REXS experiments are performed at space group forbidden reflections, where high order contributions as Thomson scattering are not allowed. The data gathered at these weak Bragg reflections, due to space group symmetry rules, can be treated using an atomic model, which has the virtue of being used as a common platform for the analysis of x-ray and neutron diffraction experiments. In this PhD work, three different antiferromagnetic materials with magnetic ions located in threefold symmetry (3) positions have been investigated in detail by means of REXS. Neptunium Dioxide (NpO2), where an enigmatic low-temperature ordering state shows interesting physical features, similar to the one observed in UO2, that relates its crystal field, the super-exchange interactions and electron¿phonon coupling. Previous works from different groups have…
author: Rodríguez Fernández, Ángel
language: eng
keywords: Física fundamental y aplicada, Dispersiones, Rayos X, Magnetismo
license: http://creativecommons.org/licenses/by-nc-nd/4.0/
date published: 2014-07-24
date modified: 2026-07-24T03:41:18Z
provider: Universidad de Oviedo
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Universidad de Oviedo

PropertyValue
property ID: Handle
value: http://hdl.handle.net/10651/29163