Die intermetallischen Verbindungen der RCu2-Serie (R = Seltenerd-Elemente) zeigen eine ungewöhnliche Vielfalt von magnetischen Strukturen in Abhängigkeit von Temperatur und äußerem Magnetfeld. Diese Vielfalt ist verursacht durch das Wechselspiel von indirekter Austauschwechselwirkung und anisotropem kristallelektrischen Feld. Die RCu2-Verbindungen kristallisieren in der CeCu2-Struktur, welche als orthorhombische Verzerrung der hexagonalen AlB2-Struktur verstanden werden kann. Ziel der vorliegenden Arbeit ist es, RCu2-Verbindungen mit magnetischer Röntgenbeugung bzw. resonanter magnetischer Röntgenstreuung zu untersuchen, teilweise ergänzt durch Neutronenbeugungsexperimente. Dem zur Neutronenbeugung komplementären Charakter der Röntgenmethoden entspricht es, dass dabei spezielle Details der magnetischen Strukturen untersucht werden. Zusätzlich zur Untersuchung der magnetischen Eigenschaften und Strukturen und zur Suche nach den Ursachen für die auftretenden Phasenübergänge werden magnetoelastische Kopplungen in der pseudohexagonalen Substanzgruppe betrachtet (R = Nd, Gd, Tb, Dy). Der Zusammenhang von kristalliner und magnetischer Struktur wird auch unter Variation und Mischung der Elemente auf dem Seltenerd-Platz erforscht (Tb(1-x)DyxCu2, Tb(1-x)PrxCu2, Dy(1-x)YxCu2). Für die Untersuchung des elementspezifischen Magnetismus bei Vorhandensein mehrerer magnetischer Atomsorten in einem Kristall ist dabei die resonante magnetische Röntgenstreuung die einzig verfügbare Methode. Im Tb0.5Dy0.5Cu2 wird dabei ein unerwartetes Verhalten im Temperaturverlauf der magnetischen Strukturen beobachtet. Ergebnisse aus ergänzenden Neutronenbeugungsexperimenten werden ebenfalls vorgestellt und mittels Rietveld-Verfeinerung der kristallinen und magnetischen Strukturen ausgewertet. Im Ergebnis der Arbeit sind die untersuchten magnetischen Strukturen näher bekannt. Magnetoelastische Wechselwirkungen werden unter Verwendung von Beugungsmethoden neuartig gemessen. / The intermetallic compounds of the RCu2 series (R = rare earths) show a large variety of magnetic structures depending on temperature and external field, mainly caused by the interplay of an indirect exchange interaction and the anisotropy of the crystalline electric field. The RCu2 compounds crystallize in the CeCu2 structure, which can be described as an orthorhombic distortion of the hexagonal AlB2 structure. The aim of the present work is the investigation of RCu2 compounds by using resonant and nonresonant magnetic x-ray scattering, supplemented by neutron scattering. Because of the complementarity of magnetic x-ray and neutron scattering this investigation reveals new details of the magnetic structures of the studied compounds. Magnetic properties and magnetic structures are investigated as well as magnetic phase transitions and magneto-elastic coupling in the pseudohexagonal compounds. The correlation between the crystallographic structure and the magnetic structures is studied for different rare earths (R = Nd, Gd, Tb, Dy) but also for partial substitution of magnetic rare earths by magnetic or nonmagnetic ions on the rare earth site (Tb(1-x)DyxCu2, Tb(1-x)PrxCu2, Dy(1-x)YxCu2). Resonant magnetic x-ray scattering is the only method available to investigate the element specific magnetism in crystals with different magnetic ions. By the study of the Tb resonance and the Dy resonance on Tb0.5Dy0.5Cu2 an unexpected developement of the magnetic structures with temperature is observed. The results of supplementary neutron scattering experiments are presented and analyzed by Rietveld refinement of the crystallographic and magnetic structures, mainly focussed on TbCu2. In summary, new insights into the different magnetic structures of RCu2 compounds are gained. The strong magneto-elastic coupling is studied by different scattering methods applied to this problem for the first time.

Die intermetallischen Verbindungen der RCu2-Serie (R = Seltenerd-Elemente) zeigen eine ungewöhnliche Vielfalt von magnetischen Strukturen in Abhängigkeit von Temperatur und äußerem Magnetfeld. Diese Vielfalt ist verursacht durch das Wechselspiel von indirekter Austauschwechselwirkung und anisotropem kristallelektrischen Feld. Die RCu2-Verbindungen kristallisieren in der CeCu2-Struktur, welche als orthorhombische Verzerrung der hexagonalen AlB2-Struktur verstanden werden kann. Ziel der vorliegenden Arbeit ist es, RCu2-Verbindungen mit magnetischer Röntgenbeugung bzw. resonanter magnetischer Röntgenstreuung zu untersuchen, teilweise ergänzt durch Neutronenbeugungsexperimente. Dem zur Neutronenbeugung komplementären Charakter der Röntgenmethoden entspricht es, dass dabei spezielle Details der magnetischen Strukturen untersucht werden. Zusätzlich zur Untersuchung der magnetischen Eigenschaften und Strukturen und zur Suche nach den Ursachen für die auftretenden Phasenübergänge werden magnetoelastische Kopplungen in der pseudohexagonalen Substanzgruppe betrachtet (R = Nd, Gd, Tb, Dy). Der Zusammenhang von kristalliner und magnetischer Struktur wird auch unter Variation und Mischung der Elemente auf dem Seltenerd-Platz erforscht (Tb(1-x)DyxCu2, Tb(1-x)PrxCu2, Dy(1-x)YxCu2). Für die Untersuchung des elementspezifischen Magnetismus bei Vorhandensein mehrerer magnetischer Atomsorten in einem Kristall ist dabei die resonante magnetische Röntgenstreuung die einzig verfügbare Methode. Im Tb0.5Dy0.5Cu2 wird dabei ein unerwartetes Verhalten im Temperaturverlauf der magnetischen Strukturen beobachtet. Ergebnisse aus ergänzenden Neutronenbeugungsexperimenten werden ebenfalls vorgestellt und mittels Rietveld-Verfeinerung der kristallinen und magnetischen Strukturen ausgewertet. Im Ergebnis der Arbeit sind die untersuchten magnetischen Strukturen näher bekannt. Magnetoelastische Wechselwirkungen werden unter Verwendung von Beugungsmethoden neuartig gemessen. / The intermetallic compounds of the RCu2 series (R = rare earths) show a large variety of magnetic structures depending on temperature and external field, mainly caused by the interplay of an indirect exchange interaction and the anisotropy of the crystalline electric field. The RCu2 compounds crystallize in the CeCu2 structure, which can be described as an orthorhombic distortion of the hexagonal AlB2 structure. The aim of the present work is the investigation of RCu2 compounds by using resonant and nonresonant magnetic x-ray scattering, supplemented by neutron scattering. Because of the complementarity of magnetic x-ray and neutron scattering this investigation reveals new details of the magnetic structures of the studied compounds. Magnetic properties and magnetic structures are investigated as well as magnetic phase transitions and magneto-elastic coupling in the pseudohexagonal compounds. The correlation between the crystallographic structure and the magnetic structures is studied for different rare earths (R = Nd, Gd, Tb, Dy) but also for partial substitution of magnetic rare earths by magnetic or nonmagnetic ions on the rare earth site (Tb(1-x)DyxCu2, Tb(1-x)PrxCu2, Dy(1-x)YxCu2). Resonant magnetic x-ray scattering is the only method available to investigate the element specific magnetism in crystals with different magnetic ions. By the study of the Tb resonance and the Dy resonance on Tb0.5Dy0.5Cu2 an unexpected developement of the magnetic structures with temperature is observed. The results of supplementary neutron scattering experiments are presented and analyzed by Rietveld refinement of the crystallographic and magnetic structures, mainly focussed on TbCu2. In summary, new insights into the different magnetic structures of RCu2 compounds are gained. The strong magneto-elastic coupling is studied by different scattering methods applied to this problem for the first time.

Studiens mål är att bidra till kunskapsutveckling om hur unga människor utvecklar handlingskompetens för hållbar utveckling. Med handlingskompetens för hållbar utveckling avses i studien vilja och förmåga att påverka livsstil och levnadsvillkor på ett sätt sominkluderar intergenerationellt och globalt ansvar. I avhandlingen introduceras begreppet avståndsmoral för att beskriva detta ansvar, som utsträcker sig i både tid och rum, till kommande generationer och till nu levande människor globalt. En utgångspunkt för studien är att hållbar utveckling innefattar idén om avståndsmoraliskt ansvar. Studiens huvudfråga är: Hur erfar avståndsmoraliskt aktivt handlande unga människor att de utvecklat handlingskompetens för hållbar utveckling? Studiens teorigrund är livsvärldsfenomenologisk. En upplevd verklighet undersöks i studien via berättelser. Genom ett strategiskt urval har tre intervjupersoner, som motiverar sina handlingar med avståndsmoraliska argument, valts att ingå i studien. Datainsamlingen har skett genom en kombination av öppna livsberättelseintervjuer ochhalvstrukturerade intervjuer. Analys och tolkning har metodologiskt stöd i berättelseforskningstraditionen och empirisk fenomenologisk forskning. Resultaten presenteras som tre citatrika levnadsberättelser om Karin, Carl och Matilda, tre unga vuxna med flera års engagemang i hållbarhetsfrågor. Syftet med levnadsberättelserna är att bidra till förståelse av det speciella i en enskild individs upplevelse av attutveckla handlingskompetens för hållbar utveckling. En integrerande analys redovisar mönster i form av likheter och skillnader mellan de tre individernas berättelser om att utveckla olika aspekter av handlingskompetens i avståndsmoraliska frågor. Sex gemensammakärnpoänger framstår som betydelsefulla: känslomässiga reaktioner, upplevd kompetens, kontrasterande perspektiv och normativ grund, handlingsimpregnering, tillit från och tillit till vuxna samt social gemenskap kontra utanförskap. Som motiv och drivkrafterför engagemanget framstår känslomässiga reaktioner som initierar önskan om förändring och vilja till handling, längtan efter meningsfullhet, önskan om att komma till sin rätt och längtan efter gemenskap. Resultaten diskuteras i förhållande till tidigare forskningoch en modell av en möjlig väg att utveckla aspekter av handlingskompetens för hållbar utveckling presenteras. Diskussionskapitlet utmynnar i fyra didaktiska utmaningar för enutbildning för hållbar utveckling. / The aim of the study at hand is to develop knowledge about the process of developing action competence for sustainable development. The overall research question explored is: How do young people experience that they have developed aspects of action competence forsustainable development? For the purposes of this study, action competence for sustainable development is defined as willingness and capability to act for changes in individual life style, as well as for structural changes of society, in a way that includes responsibility for present and future generations,globally. Life-world phenomenology provides the theoretical foundation of the study. Through purposive sampling, individuals have been found who, through different action strategies, engage in sustainability issues as for example climate change, bio-diversity and social justice. From a larger sample, three young adults have been selected for several life storyinterviews. Data has been analyzed and interpreted by use of narrative methodology. The result is presented as three stories, presented as thick descriptions, through whichthe winding paths towards aspects of action competence, as experienced, appear. This is followed by an integrative analysis presenting six themes that have emerged in theanalyses as relevant in the process of developing action competence for sustainable development: emotional reactions; perceived competence; contrasts and normative foundation;action permeation; trust and faith from adults and in adults; and social belonging in contrastto outsidership. Major motives and driving-forces for sustainability actions that emerge inthe stories are: emotional reactions initiating a desire for change and a desire to act; longingfor meaningfulness; a desire to feel comfortable with what you can contribute; and longing for belongingness. The findings are discussed in relationship to previous research and a modelof a possible way to develop aspects of action competence for sustainable development is introduced. This dissertation is part of a project supported by Formas, The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning.

L’écomobilité en milieu scolaire, étudiée à travers le Pédibus ou walking school bus, système de ramassage pédestre organisant bénévolement le trajet domicile-école à l’initiative des parents, peut questionner l’éducation relative à l’environnement (ERE) et l’éducation au développement durable (EDD). S’inscrivant à la suite des travaux de Lucie Sauvé, Sandrine Depeau, Alain Legardez, Angela Barthes, Marie-Louise Martinez et Jean-Marc Lange, les analyses ont cherché à montrer comment la pratique du Pédibus peut devenir un enjeu éducatif qui touche aux finalités de l’éducation : « construire des savoirs », « construire une identité de sujet et de citoyen », « devenir une personne responsable évoluant au sein d’une communauté ». Le point de départ a été d’interroger la façon dont le discours véhiculé par les textes officiels, dont les grandes déclarations onusiennes fondatrices du développement durable (DD), voient en l’école le lieu fondamental de la formation des esprits conscients et responsables. A ces discours prônant une réforme par le haut, la thèse a mis en regard les discours des acteurs du Pédibus en Métropole Rouen Normandie, recueillis entre 2016 et 2018, afin de montrer comment s’articule un discours écocitoyen, inscrit dans un processus de réforme par la base et par l’action quotidienne. S’inspirant des études sur l’écocitoyenneté, en particulier des travaux de Marie-Louise Martinez, l’analyse interlocutive des discours a mis en évidence la constitution d’une conscience écocitoyenne et l’émergence d’une personne écoresponsable, inscrite dans son milieu urbain et naturel, ainsi que dans son milieu social (rue, quartier, ville). Par ailleurs, cette thèse constitue la première monographie universitaire consacrée au Pédibus, incluant un état de la recherche inspiré de divers pays et de domaines différents (sciences de l’éducation, médecine, sociologie, géographie) concernés par le « car-à-pattes », à l’origine des principaux types de discours portant sur un objet complexe (discours sécuritaire, hygiéniste, sociétal, environnemental). Conformément à la nature même d’un processus d’apprentissage dénué de curriculum et dont la compréhension peut s’inspirer des travaux de l’éco-ontogénèse dans l’esprit de Tom Berryman, les relations entre apprentissage non formel et apprentissage formel ont été interrogées, d’autant que les élèves concernés relèvent du « cycle des observations » et du « cycle de consolidation » de l’école primaire. Sur ces bases, la thèse a formulé des pistes de remédiation, susceptibles de renforcer la synergie entre éducation non formelle et éducation formelle d’une part, et de contribuer à la multiplication et à la pérennisation des lignes de Pédibus d’autre part, très engagée depuis des décennies dans les « déplacements doux », pourrait servir de modèle dans le domaine de l’écomobilité. / Eco-mobility in connection with schools, studied through the Walking School Bus, a pedestrian collecting system that voluntarily organizes the home-school journey for young pupils at the initiative of some parents, can raise questions about environmental education (EE) and education for sustainable development (ESD). Following the work of Lucie Sauvé, Sandrine Depeau, Alain Legardez, Angela Barthes, Marie-Louise Martinez and Jean-Marc Lange, the analyses sought to show how the practice of the Walking School Bus can become an educational issue that touches on the aims of education: "building knowledge", "building an identity as a subject and a citizen", "becoming a responsible person evolving within a community". The starting point was to question how the discourse conveyed by official texts, including the major UN declarations founding sustainable development (SD), see schools as the fundamental place for the training of conscious and responsible minds. To these discourses advocating a reform from above, the thesis compared the discourses of the actors of the Walking School Bus in Rouen Normandy Metropolis, collected between 2016 and 2018, in order to show how an eco-citizen discourse is articulated, as part of a reform process from the bottom up, and through daily action. Inspired by studies on eco-citizenship, in particular the work of Marie-Louise Martinez, the interlocutory analysis of the discourses highlighted the creation of an eco-citizen awareness and the emergence of an eco-responsible person, inscribed in its urban and natural environment, as well as in its social environment (street, neighborhood, city). Moreover, this thesis is the first university monograph devoted to the Walking School Bus, including a state of research inspired by various countries and different fields of science (educational sciences, medicine, sociology, geography) concerned by the WSB, at the origin of the main types of discourse on a complex subject (safety, hygienist, societal, environmental discourse). In accordance with the very nature of a curriculum-free learning process whose understanding can be inspired by the work of eco-ontogenesis in Tom Berryman's mind, the relationship between non-formal and formal learning was questioned, especially because the pupils concerned fall within the "observation cycle" and the "consolidation cycle" of primary school. On this basis, the thesis formulated remedial approaches that could strengthen the synergy between non-formal and formal education on the one hand, and contribute to the multiplication and sustainability of the Walking School Bus lines on the other hand. Rouen Normandy Metropolis, which has been very much involved for decades in "soft mobility", could serve as a model in the field of eco-mobility.

The subject of this thesis is to study the interaction between carbon nanotubes (CNTs) and antiferromagnetic tetrametallic molecules attached to them. By employing quantum transport measurements, the sensitivity to sense the interactions is greatly increased, because the quantum dot is very susceptible to changes in its environment. The properties of carbon nanotubes can be altered by chemical functionalization with the aforementioned molecules, where the attachment is performed covalently via a ligand exchange with the CNT. The thesis is partitioned into two main parts: the first part presents experiments performed on tetramanganese functionalized CNTs, whereas for the second similar studies are conducted, except manganese is replaced by cobalt. Both complexes exhibit an antiferromagnetic ground state, yet the metal spin of manganese (S=5/2) is reduced to S=3/2 for cobalt. Additionally, an altered device preparation has been employed during the second part, leading to a strong suppression of the background signal. Quantum transport measurements at T=4K on manganese-functionalized CNTs show a very regular pattern of Coulomb diamonds, indicating only a mild disturbance of the quantum dot's electron system by the covalent bond. Moreover, the charging energy reveals a wave function extending over the entire device dimensions. However, at T=30mK in the tunneling current a strong noise emerges, when repeatedly measuring over an hour while keeping external biases constant. Additionally, these time traces are superimposed by a long-term background, which is removed by a correction algorithm plus a subsequent digitization. The remaining signal reveals a random telegraph signal (RTS) which is extensively studied and from its statistics the equivalent temperature of T=654mK for the excitation of the system is extracted. The quantum transport experiments conducted on cobalt-functionalized CNTs show a much better data quality of the coulomb diamonds, which is ascribed to the alteration in the device's preparation. From the line shape of the Coulomb oscillations as well as from the Coulomb staircases an electron temperature of about T=500mK is extracted. Moreover, a magnetic field dependence of the stability diagrams is apparent, attributable to Zeeman splitting. The respective Landé factor of g=1.73 is, compared to similar CNT quantum dot systems, unusually low. It is as attributed to an increased spin-orbit interaction between the conduction electrons and the cobalt's nuclei. The respective time traces exhibit or lack an RTS signal, depending on their external biases. Regarding the Coulomb diamonds, an essential prerequisite for the occurrence of an RTS is the proximity to a resonance, which is equatable to a high sensitivity of the quantum dot detector. Considering the available energy, the underlying process that is the cause for the emergence of the RTS is ascertained to be an internal excitation of the antiferromagnetic states of the metallic core.

Quasi-particles formed in lithium niobate after pulse exposure were investigated by transient absorption and photoluminescence spectroscopy as well as numerical simulations. This includes the formation process, the transport through the crystal, interim pinning on defects during the relaxation process, and the final recombination with deep centers. It was shown that the charge-transport through the crystal can be described by a hopping transport including different types of hops between regular or defective lattice sites, i.e., the transport includes a mixture of free and bound small polarons. Furthermore, the different types of hops connected with varying activation energies and their distribution are responsible for an altered temporal decay curve when changing the crystal composition or temperature. Additionally, it was shown that the hitherto accepted recombination model is insufficient to describe all transient absorption and luminescence effects in lithium niobate under certain experimental conditions, i.e., long-living absorption dynamics in the blue/UV spectral range do not follow the typical polaron dynamics and cannot be described under the assumption of charge compensation. However, similar decay characteristics between self-trapped excitons known from photoluminescence spectroscopy and the unexpected behavior of the transient absorption were found leading to a revised model. This includes, besides the known polaron relaxation and recombination branch, a significant role of self-trapped excitons and their pinning on defects (pinned STEs). Since the consideration of further absorption centers in the relaxation path after pulse exposure might result in misinterpretations of previously determined polaron absorption cross-sections and shapes, the necessity to perform a review became apparent. Therefore, a supercontinuum pump-probe experiment was designed and all measurements applied under the same experimental conditions (temperature, polarization) so that one can extract the absorption amplitudes of the single quasi-particles in a spectral range of 0.7-3.0eV. The detailed knowledge might be used to deconvolve the absorption spectra and transform them to number densities of the involved centers which enables one to obtain an easier insight into recombination and decay dynamics of small polarons and self-trapped excitons. As the hopping transport of quasi-particles and the concept of pinned STEs might be fundamental processes, a thorough understanding opens up the possibility of their exploitation in various materials. In particular, results presented herein are not only limited to lithium niobate and its applications; an extension to a wide range of further strongly polar crystals in both their microscopic processes and their use in industry can be considered.

Since the synthesis of Mn12, which can be regarded as the birth of the class of magnetic molecules, many different molecules of various sizes and structures have been produced. The magnetic nature of these molecules originates from a number of paramagnetic ions, whose unpaired electrons form collective angular momenta, referred to as spins. The interaction between these spins can often be described in the Heisenberg model. In this work, we use the rotational band model to predict the energy spectrum of the giant Keplerate {Mo72Fe30}. Based on the approximate energy spectrum, we simulate the cross-section for inelastic neutron scattering, and the results are compared to experimental data. The successful application of our approach substantiates the validity of the rotational band model. Furthermore, magnetic molecules can serve as an example for studying general questions of quantum mechanics. Since chemistry now allows the preparation of magnetic molecules with various spin quantum numbers, this class of materials can be utilized for studying the relations between classical and quantum regime. Due to the correspondence principle, a quantum spin system can be described exactly by classical physics for an infinitely large spin quantum number s. However, the question remains for which quantum numbers s a classical calculation yields a reasonable approximation. Our approach in this work is to develop a converging scheme that adds systematic quantum corrections to the classical density of states for Heisenberg spin systems. To this end, we establish a correspondence of the classical density of states and the quantum spectrum by means of spin-coherent states. The algorithm presented here allows the analysis of how the classical limit is approached, which gives general criteria for the similarity of the classical density of states to the quantum spectrum.

This master's thesis deals with the problem of monitoring of a presence state from multiple points. It begins with analysis of presence information propagation in various systems and also with multiple points of presence in general terms. After that follows requirements analysis and design of information system which will evaluate presence information from multiple sources with various features and than display it graphically on plans or maps. At the conclusion there is described implementation and testing of developed information system.