Cette thèse à pour objet l'étude expérimentale de la dynamiquede l'aimantation de disques de taille sub-micronique fait dematériau ferromagnétiques à faible amortissement . Pour cela,nous avons utilisé une technique spectroscopique extremementsensible qui sera préalablement présentée: la résonanceferromagnétique détéctée mécaniquement. Une premièrepartie est consacrée à la mesure des modes propres dans des disquesde NiMnSb dans leur état rémanent: le vortex. L'influence d'unchamp magnétique, aplliqué perpendiculairement, sur les ondes despin du vortex est détaillé. L'accent est ensuite mis surl'interaction du coeur de vortex avec ces ondes de spin, qui mèneà son retournement dynamique. Un cadre théorique de l'étatvortex est présenté, permettant de modéliser les mesuresexpérimentales. Dans une deuxième partie, le problème de ladynamique collective de plusieurs disques de FeV dont l'aimantation estsaturée perpendiculairement est étudié. La mesure des modescouplés par l'intéraction dipolaire dynamique y est présentée,associée à une modélisation théorique qui expliquequantitativement les résultats observés. / This thesis is aimed at studying experimentally the magnetisationdynamics of discs in the sub-micron range made of low dampingferromagnetic materials. For this purpose, an extremely sensitivetechnique has been used: the ferromagnetic resonance force microscopy. A firstpart is devoted to the measurement of the eigenmodes of NiMnSb discstaken in their remanent state: a vortex. The influence of aperpendicular magnetic field on the spin wave modes in the vortex state willbe detailled. Then, the coupling mechanism between the vortex core andthese spin wave, eventually leading to its dynamical reversal, ishighlighted. A theoretical framework of the vortex state is presented,allowing to model the experimental observations. In a second part,the problem of the collective magnetisation dynamics in several FeVdiscs is addressed. Measurements of the collective modes coupled bythe dynamical dipolar interaction are presented, associated with atheoretical modelisation which explain quantitatively the experimentalresults.

This thesis is focused on the electronic, spin-dependent and dynamical properties of thin magnetic systems. Photoemission-related techniques are combined with synchrotron radiation to study the spin-dependent properties of these systems in the energy and time domains. In the first part of this thesis, the strength of electron correlation effects in the spin-dependent electronic structure of ferromagnetic bcc Fe(110) and hcp Co(0001) is investigated by means of spin- and angle-resolved photoemission spectroscopy. The experimental results are compared to theoretical calculations within the three-body scattering approximation and within the dynamical mean-field theory, together with one-step model calculations of the photoemission process. From this comparison it is demonstrated that the present state of the art many-body calculations, although improving the description of correlation effects in Fe and Co, give too small mass renormalizations and scattering rates thus demanding more refined many-body theories including nonlocal fluctuations. In the second part, it is shown in detail monitoring by photoelectron spectroscopy how graphene can be grown by chemical vapour deposition on the transition-metal surfaces Ni(111) and Co(0001) and intercalated by a monoatomic layer of Au. For both systems, a linear E(k) dispersion of massless Dirac fermions is observed in the graphene pi-band in the vicinity of the Fermi energy. Spin-resolved photoemission from the graphene pi-band shows that the ferromagnetic polarization of graphene/Ni(111) and graphene/Co(0001) is negligible and that graphene on Ni(111) is after intercalation of Au spin-orbit split by the Rashba effect. In the last part, a time-resolved x-ray magnetic circular dichroic-photoelectron emission microscopy study of a permalloy platelet comprising three cross-tie domain walls is presented. It is shown how a fast picosecond magnetic response in the precessional motion of the magnetization can be induced by means of a laser-excited photoswitch. From a comparision to micromagnetic calculations it is demonstrated that the relatively high precessional frequency observed in the experiments is directly linked to the nature of the vortex/antivortex dynamics and its response to the magnetic perturbation. This includes the time-dependent reversal of the vortex core polarization, a process which is beyond the limit of detection in the present experiments. / Diese Dissertation beschäftigt sich mit den elektronischen, spinabhängigen und dynamischen Eigenschaften dünner magnetischer Systeme. Auf dem Photoeffekt basierende Untersuchungsmethoden werden zusammen mit Synchrotronstrahlung eingesetzt, um die spinabhängigen Eigenschaften dieser Systeme im Energie- und Zeitbereich zu untersuchen. Im ersten Teil dieser Arbeit wird mit spin- und winkelaufgelöster Photoemission die Stärke von Elektronenkorrelationseffekten in der spinabhängigen elektonischen Struktur von ferromagnetischerm bcc Fe(110) und hcp Co(0001) untersucht. Die experimentellen Ergebnisse werden verglichen mit theoreteischen Berechnungen im Rahmen der Näherung der Drei-Körper-Streuung und der dynamischen Molekularfeldtheorie, zusammen mit Berechnungen des Photoemissionsprozesses im Rahmen des Ein-Stufen-Modells. Ausgehend von diesem Vergleich wird gezeigt, dass die gegenwärtig fortgeschrittensten Rechnung, obgleich sie die Beschreibung von Korrelationseffekten in Fe und Co verbessern, zu kleine Massenrenormalisierungen und Streuraten ergeben, was zu der Forderung nach verfeinerten Vielteilchentheorien unter Einbeziehung von nichtlokalen Fluktuationen führt. Im zweiten Teil wird unter Kontrolle durch die Photoelektronenspektroskopie im Detail gezeigt, wie Graphen durch chemische Gasphasenabscheidung auf den Übergangsmetall-Oberflächen Ni(111) und Co(0001) aufgebracht und mit einer Monolage Au interkaliert werden kann. Für beide Systeme wird eine lineare E(k)-Dispersion masseloser Dirac-Fermionen im Graphen-pi-Band in der Nähe der Fermi-Energie beobachtet. Spinaufgelöste Photoemission des Graphen-pi-Bandes zeigt, dass die ferromagnetische Polarisation von Graphen/Ni(111) und Graphen/Co(0001) vernachlässigbar ist und dass Graphen/Ni(111) nach Interkalation mit Au eine Spin-Bahn-Aufspaltung aufgrund des Rashba-Effekts zeigt. Im letzten Teil wird eine zeitaufgelöste Studie des Röntgenzirkulardichroismus mit Photoelektronenmikroskopie präsentiert, die an einer Permalloy-Probe durchgeführt wurde, die drei als Stachelwände ausgebildete Domänenwände enthält. Es wird gezeigt, wie eine schnelle magnetische Antwort auf der Pikosekundenskala in der Präzessionsbewegung der Magnetisierung durch einen laserangesteuerten Photoschalter erzeugt werden kann. Durch Vergleich mit einer mikromagnetischen Rechnung wird gezeigt, dass die relativ hohe Präzessionsfrequenz, die im Experiment beobachtet wird, in unmittelbarer Beziehung steht zu den Eigenschaften der Vortex/Antivortex-Dynamik und ihrer Antwort auf die magnetische Störung. Das schließt die zeitabhängige Umkehr der Vortexkernpolarisation ein, einem Vorgang der jenseits der Nachweisgrenze der gegenwärtigen Experimente liegt.

The primary study of this thesis is spin-nematic squeezing in a spin-1 condensate. The measurement of spin-nematic squeezing builds on the success of previous experiments of spin-mixing together with advances in low noise atom counting. The major contributions of this thesis are linking theoretical models to experimental results and the development of the intuition and tools to address the squeezed subspaces. Understanding how spin-nematic squeezing is generated and how to measure it has required a review of several theoretical models of spin-mixing as well as extending these existing models. This extension reveals that the squeezing is between quadratures of a spin moment and a nematic (quadrapole) moment in abstract subspaces of the SU(3) symmetry group of the spin-1 system. The identification of the subspaces within the SU(3) symmetry allowed the development of techniques using RF and microwave oscillating magnetic fields to manipulate the phase space in order to measure the spin-nematic squeezing. Spin-mixing from a classically meta-stable state, the phase space manipulation, and low noise atom counting form the core of the experiment to measure spin-nematic squeezing. Spin-nematic squeezing is also compared to its quantum optics analogue, two-mode squeezing generated by four-wave mixing. The other experimental study in this thesis is performing spin-dependent photo-association spectroscopy. Spin-mixing is known to depend on the difference of the strengths of the scattering channels of the atoms. Optical Feshbach resonances have been shown to be able to alter these scattering lengths but with prohibitive losses of atoms near the resonance. The possibility of using multiple nearby resonances from different scattering channels has been proposed to overcome this limitation. However there was no spectroscopy in the literature which analyzes for the different scattering channels of atoms for the same initial states. Through analysis of the initial atomic states, this thesis studies how the spin state of the atoms affects what photo-association resonances are available to the colliding atoms based on their scattering channel and how this affects the optical Feshbach resonances. From this analysis a prediction is made for the extent of alteration of spin-mixing achievable as well as the impact on the atom loss rate.

Bose-Einstein condensation (BEC) is a phenomenon in which identical bosons occupy the same quantum state below a certain critical temperature. A hallmark of BEC is the coherence between particles every particle shares the same quantum wavefunction and phase. This coherence has been demonstrated for the external (motional) degrees of freedom of the atomic condensates by interfering two condensates. In this thesis, the coherence is shown to extend to the internal spin degrees of freedom of a spin-1 Bose gas evidenced by the observed coherent and reversible spin-changing collisions. The observed coherent dynamics are analogous to Josephson oscillations in weakly connected superconductors and represent a type of matter-wave four-wave mixing. Control of the coherent evolution of the system using magnetic fields is also demonstrated. The studies on spinor condensates begin by creating spinor condensates directly using all-optical approaches that were first developed in our laboratory. All-optical formation of Bose-Einstein condensates (BEC) in 1D optical lattice and single focus trap geometries are developed and presented. These techniques offer considerable flexibility and speed compared to magnetic trap approaches, and the trapping potential can be essentially spin-independent and are ideally suited for studying spinor condensates. Using condensates with well-defined initial non-equilibrium spin configuration, spin mixing of F = 1 and F = 2 spinor condensates of rubidium-87 atoms confined in an optical trap is observed. The equilibrium spin configuration in the F = 1 manifold confirms that 87Rb is ferromagnetic. The coherent spinor dynamics are demonstrated by initiating spin mixing deterministically with a non-stationary spin population configuration. Finally, the interplay between the coherent spin mixing and spatial dynamics in spin-1 condensates with ferromagnetic interactions is investigated.

SENA FILHO, Roberto Ferreira. Teoria microscópica de ondas de spin em nanofios magnéticos. 2007. 74 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2007. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-05-22T19:45:31Z No. of bitstreams: 1 2007_dis_rfsenafilho.pdf: 3612063 bytes, checksum: 5cbe75be9b4bf3c77cd9b1136fad2a2a (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-05-22T19:46:04Z (GMT) No. of bitstreams: 1 2007_dis_rfsenafilho.pdf: 3612063 bytes, checksum: 5cbe75be9b4bf3c77cd9b1136fad2a2a (MD5) / Made available in DSpace on 2015-05-22T19:46:04Z (GMT). No. of bitstreams: 1 2007_dis_rfsenafilho.pdf: 3612063 bytes, checksum: 5cbe75be9b4bf3c77cd9b1136fad2a2a (MD5) Previous issue date: 2007 / The dynamical behavior of spins in magnetic materials is affected by its geometry and dimensionality. One can find several new results in the literature exploiting the magnetic properties of low dimension systems with different geometries, since the development of new devices such as: nanosensors, high density magnetic storage, etc., is closely related to new geometries. In this piece of work, we study the propagation of spin waves on cylindrical magnetic nanowires described by a microscopic theory through the Heisenberg Hamiltonian, where we consider the spins fixed at the sites lattice and the transversal section of the wire is hexagonal. Our model takes into account the exchange interaction between the spins that can be ferromagnetic or antifferomagnetic, the interaction of an external field with the spins (Zeeman interaction), anisotropic interactions due to a preferred direction of magnetization, and finally dipole-dipole interactions. The spins are described by boson operators through Holstein-Primakoff representation. The equations of motion for the spins are written in terms of these operators and translational symmetry in a preferential direction allows us to calculate several excitations spectra. / O comportamento dinâmico de spins em materiais magnéticos é influenciado pela geometria que eles apresentam. Além disso, outro aspecto relevante é a dimensionalidade do sistema. Trabalhos recentes comprovam o interesse do estudo das propriedades magnéticas em sistemas de baixa dimensionalidade, que é devido em grande parte as aplicações tecnológicas, tais como: nanosensores, gravadores magnéticos de alta densidade, dispositivos magneto-eletrônicos, etc. Neste trabalho estudamos a propagação de ondas de spin em nanofios magnéticos cilíndricos, onde a abordagem é feita utilizando teoria microscópica, através do Hamiltoniano de Heisenberg, em que os spins são considerados fixos nos sítios da rede e cuja geometria da seção transversal dos cilindros é hexagonal. Entre as interações magnéticas estudadas consideramos: a interação de troca que pode ser ferromagnética se os primeiros vizinhos dos spins estão numa configuração paralela, ou antiferromagnética se estiverem antiparelelos; a interação Zeeman que é devido ao campo magnético externo aplicado ao sistema; a interação de Anisotropia, esta sendo responsável pela direção de magnetização preferida que diversos sistemas magnéticos reais apresentam e a interação dipolar de natureza magnetostática, presente em todos os materiais. O formalismo leva em consideração a dependência espacial dos spins no sistema, onde os operadores de spin do hamiltoniano são escritos em termos de operadores bosônicos de criação e aniquilação através da Representação de Holstein-Primakoff. Em seguida, aproveitando-se da simetria translacional em uma direção devido a periodicidade da rede, realizamos a transformada de Fourier para estes operadores fornecendo um sistema de equações matriciais no espaço dos vetores de onda. A partir desse sistema de equações obtemos vários espectros de excitação como: a relação de dispersão para as ondas de spin, que é o gráfico onde mostra como a frequência de ondas de spin varia em função do vetor de onda e a variação da energia do sistema com o campo aplicado.

O formalismo matemático da teoria das ondas de spin é analisado. A equivalência entre as transformações de Dyson-Malleev e Holstein-Pr imakoff é demonstrada. Os problemas envolvendo a interação cinemática são discutidos em detalhe. Uma nova divisão do Hamiltoniano de Heisenberg, desenvolvida no espaço de configuração, é usada para estudar a interação dinâmica entre as ondas de spin a baixa temperatura e para grandes valores do número quântico de spin S. Assumindo que a restrição cinemática pode ser neglicenciada, a expansão da energia livre é desenvolvida em potências da temperatura e os resultados estão em acordo com os de Dyson. A relevância da aproximação diagonal de Mattis é demonstrada. Usando o método da positividade por reflexão, limites superiores e inferiores para a contribuição da energia livre são encontrados. Dentro de certa aproximação, estes limites significam que a interação dinâmica pode ser neglicenciada caso o inverso da temperatura (=1/KT), eo número quântico de spin S, forem grandes o suficiente, porém com dependente de S nestas estimativas. Este fato, que não ocorre no limite clássico, é uma característica na região das ondas de spin. / The mathematical formalismo f the spin wave theory is analysed. The thermodynamical equivalence between the Dyson-Malleev and Holstein-Primakoff transformations is proved. The problems involving the kinematical interaction are also discussed in detail. A new splitting of the Heisenberg Hamiltonian, perfomed in configuration space, is used to study the spin wave dynamical interaction at low temperature and for large values of the spin quantum number S. Assuming the the kinematical restriction may be lifted, a low temperature espansion of the free energy is developed with results in agreement with Dysons. The relevance of the Mattis diagonal approximation for the dynamical interaction is demonstrated. Using the method of reflection positivity, upper and lower bounds to the contribuition of the dynamical interaction to the free energy are provided. In a certain approximation, these bounds mean that the dynamical interaction may be dropped IF the inverse temperature (=1/KT) and the spin quantum number S are large enough but depends on S in the estimates, a novel feature wich does not occur in the classical limit but is characteristic of the spin-wave limit.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O comportamento dinÃmico de spins em materiais magnÃticos à influenciado pela geometria que eles apresentam. AlÃm disso, outro aspecto relevante à a dimensionalidade do sistema. Trabalhos recentes comprovam o interesse do estudo das propriedades magnÃticas em sistemas de baixa dimensionalidade, que à devido em grande parte as aplicaÃÃes tecnolÃgicas, tais como: nanosensores, gravadores magnÃticos de alta densidade, dispositivos magneto-eletrÃnicos, etc. Neste trabalho estudamos a propagaÃÃo de ondas de spin em nanofios magnÃticos cilÃndricos, onde a abordagem à feita utilizando teoria microscÃpica, atravÃs do Hamiltoniano de Heisenberg, em que os spins sÃo considerados fixos nos sÃtios da rede e cuja geometria da seÃÃo transversal dos cilindros à hexagonal. Entre as interaÃÃes magnÃticas estudadas consideramos: a interaÃÃo de troca que pode ser ferromagnÃtica se os primeiros vizinhos dos spins estÃo numa configuraÃÃo paralela, ou antiferromagnÃtica se estiverem antiparelelos; a interaÃÃo Zeeman que à devido ao campo magnÃtico externo aplicado ao sistema; a interaÃÃo de Anisotropia, esta sendo responsÃvel pela direÃÃo de magnetizaÃÃo preferida que diversos sistemas magnÃticos reais apresentam e a interaÃÃo dipolar de natureza magnetostÃtica, presente em todos os materiais. O formalismo leva em consideraÃÃo a dependÃncia espacial dos spins no sistema, onde os operadores de spin do hamiltoniano sÃo escritos em termos de operadores bosÃnicos de criaÃÃo e aniquilaÃÃo atravÃs da RepresentaÃÃo de Holstein-Primakoff. Em seguida, aproveitando-se da simetria translacional em uma direÃÃo devido a periodicidade da rede, realizamos a transformada de Fourier para estes operadores fornecendo um sistema de equaÃÃes matriciais no espaÃo dos vetores de onda. A partir desse sistema de equaÃÃes obtemos vÃrios espectros de excitaÃÃo como: a relaÃÃo de dispersÃo para as ondas de spin, que à o grÃfico onde mostra como a frequÃncia de ondas de spin varia em funÃÃo do vetor de onda e a variaÃÃo da energia do sistema com o campo aplicado. / The dynamical behavior of spins in magnetic materials is affected by its geometry and dimensionality. One can find several new results in the literature exploiting the magnetic properties of low dimension systems with different geometries, since the development of new devices such as: nanosensors, high density magnetic storage, etc., is closely related to new geometries. In this piece of work, we study the propagation of spin waves on cylindrical magnetic nanowires described by a microscopic theory through the Heisenberg Hamiltonian, where we consider the spins fixed at the sites lattice and the transversal section of the wire is hexagonal. Our model takes into account the exchange interaction between the spins that can be ferromagnetic or antifferomagnetic, the interaction of an external field with the spins (Zeeman interaction), anisotropic interactions due to a preferred direction of magnetization, and finally dipole-dipole interactions. The spins are described by boson operators through Holstein-Primakoff representation. The equations of motion for the spins are written in terms of these operators and translational symmetry in a preferential direction allows us to calculate several excitations spectra.

Les ondes de spin sont une des voies technologiques proposées pour surmonter les obstacles que rencontre la miniaturisation des complementary metal-oxide-semiconductor (CMOS) dans la gamme du nanomètre, comme en témoignent les derniers développements en matière de dispositifs logiques à ondes de spin. Cependant, l'attrait industriel de ces preuves de concept est conditionné par leur intégration évolutive à la technologie CMOS. Ici, nous présentons des pistes ultrafines de Ta/CoFeB/MgO utilisées comme guides d'ondes de spin. Ce système a été choisi pour sa compatibilité avec les procédés CMOS, son anisotropie magnétique perpendiculaire et ses fortes interactions spin-orbite. Ces derniers sont intéressants pour manipuler les ondes de spin et ont été caractérisés par résonance ferromagnétique à couple de spin où il est démontré que l'effet Hall de spin inverse est responsable de la détection de la dynamique de magnétisation. Ensuite, nous utilisons des guides d'ondes coplanaires nanométriques intégrés pour exciter localement des ondes de spin dans une large gamme de vecteurs d'ondes. La comparaison du spectre d'ondes de spin mesuré avec les calculs analytiques montre que l'effet Hall de spin inverse permet la détection des ondes de spin indépendamment de leur vecteur d'onde avec des longueurs d'onde allant jusqu'à 150 nm. Des expériences complémentaires de diffusion de la lumière de Brillouin révèlent que les ondes de spin dans le guide d'ondes de spin ultra-mince à anisotropie magnétique perpendiculaire ont des longueurs de propagation étonnamment élevées compte tenu de l'amortissement relativement élevé des systèmes Ta/CoFeB/MgO. Ces résultats ouvrent la voie à des dispositifs à ondes de spin ultraminces compatibles CMOS avec des techniques d'excitation et de détection évolutives jusqu'à l'ordre du nanomètre, avec la perspective de contrôler les ondes de spin via des couples spin-orbite. / Spin-waves have been proposed as a possible technological path to overcome the hurdles encountered by the miniaturization of complementary metal-oxide-semiconductor (CMOS) into the nanometer range, demonstrated by recent developments in spin-wave-based logic devices. However the industrial appeal of these proofs-of-concept is conditional upon their scalable integration with CMOS technology. Here, we report on ultrathin Ta/CoFeB/MgO wires used as spin-wave waveguides. This system is chosen for its compability with CMOS processes, its perpendicular magnetic anisotropy and strong spin-orbit interactions. The latter are of interest for manipulating spin waves and are characterized via spin-torque ferromagnetic resonance where it is shown that the inverse spin Hall effect is responsible for the detection of magnetization dynamics. Following this, we use integrated nanometric coplanar waveguides to locally excite spin-waves in a broad range of wavevectors. Comparison of the measured spin-wave spectrum with analytical calculations show that the inverse spin Hall effect allows the wavevector-independent detection of spin-waves with wavelengths down to 150 nm. Complementary Brillouin light scattering experiments reveal that spin-waves in the ultrathin spin-wave waveguide with perpendicular magnetic anisotropy have unexpectedly high propagation lengths considering the relatively high damping in Ta/CoFeB/MgO systems. These findings pave the way for ultrathin CMOS-compatible spin-wave devices with excitation and detection techniques that are scalable into the nanometer range, with the prospect of controlling spin-waves via spin-orbit torques.

The present work addresses in-depth magnetic films with magnonic surface patterning of variable size. Two different kinds of such structures referred to as surface-modulated magnonic crystals were investigated: Ion-irradiated magnonic crystals and structurally etched magnonic crystals. To achieve that, two different experimental approaches were pursued. On the one hand, the magnetic moment at the surface of lithographically patterned permalloy (Ni80Fe20) films was periodically reduced by means of ion irradiation. On the other hand, structural trenches were introduced at the surface of a pre-patterned thin film by sequential ion milling. The goal is the acquisition of a fundamental understanding of the behavior of spin-wave modes in the transition from a continuous magnetic thin film to a full magnonic crystal, i.e. separated periodic magnetic structures. In the framework of this thesis, the spin-wave eigen-modes of such magnonic crystals were mainly investigated spectroscopically by means of ferromagnetic resonance. Thereby, the “Two-magnon scattering perturbation theory” and the “plane-wave method” were employed as the theoretical methodologies to understand the complex dynamics of such systems. The first is a reliable method to calculate the dynamic response of surface-modulated magnonic crystals where the modulation is of a perturbation character, i.e. small compared to the film thickness. The latter is a quasi-analytical approach to calculate the dynamic eigen-modes of magnonic crystals consisting of different components with significantly varying properties. Moreover, numerical methods were employed to get further insight into the spin dynamics of these structures. In such systems, the spin-wave behavior follows the well-known dispersion relation of flat magnetic thin films as long as the surface-modulation is small compared to the film thickness. In this work, it was shown that this circumstance can be exploited for a parameter-free determination of the exchange constant A, which is not experimentally accessible for magnetic thin films in a straightforward manner. However, once the modulation height is of significant magnitude, the dynamics of surface-modulated magnonic crystals become substantially more complex. A straightforward understanding of such kind of system is hampered by the complex interplay of different effects. On the one hand, the internal demagnetizing field reveals an alternating character and depends itself on the modulation height and the field angle. On the other hand, the dynamic eigen-modes are hybridized, i.e., they reveal different characteristics in different regions of the magnonic crystal and, in addition, they couple to each other. Here, the approach is particularly favorable to investigate the spin dynamics of surface-modulated magnonic crystals by systematically altering the modulation height of the same sample. This is mainly due to two reasons. First, the two edge cases, namely the thin film and the full magnonic crystal, are already well understood and, second, other magnetic and structural parameters remain constant. With the help of the measurement results and the simulations, the quasi-analytical theory was validated. Subsequently, the mode profiles were calculated by theory and simulation in order to analyze the mode character in the transition from a thin film to a full magnonic crystal. Two kinds of dynamic eigen-modes were identified, namely hybridized modes and localized modes. For both types, simple formulae were derived describing their characteristic dynamic behavior. Besides, transition rules were found connecting the mode number n of film modes with the mode number m of modes in the full magnonic crystal. In order to correlate the symmetry and magnitude of the demagnetizing field with the spin-wave eigen-modes, the internal fields of a strongly surface-modulated magnonic crystal were reconstructed by electron holography measurements. By reemploying the measurement results for micromagnetic simulations, the dynamics of the whole system could be reproduced. This strategy allowed for a better understanding of the link between the demagnetizing field and the spin-wave mode characteristics. Based on these results, a simplified model for the analytical description of the inplane angular dependence was found. The acquired understanding of such systems led to the elaboration of specific applications, such as the spin-wave channelization. It should be noted that the coupling of uniform to non-uniform spin-wave phenomena, which is an intrinsic property of these structures, holds out the prospect of several applications in the future.

The direct integration of magnon-spintronic devices in current technologies requires the development of spin-wave sources emitting ultra-short wavelengths and low-loss spin-wave guides. In this work, possible solutions for both of these challenges are provided. The first part of this thesis is dedicated to the nonreciprocal spin-wave emission in magnetic bilayers. Two prototype systems are theoretically investigated and corroborated by experimental results: (i) extended magnetic bilayer films and (ii) micron-sized elliptical magnetic bilayers. The nonreciprocity of the dispersion relation induced by the dynamic dipole-dipole interactions is investigated by means of micromagnetic simulations and an analytic theory. The nonreciprocal frequency shift linearly increases with the film thickness for small wave numbers. The topological emission of short-wavelength spin waves is observed in the micron-sized elliptical magnetic bilayers using scanning transmission X-ray microscopy and theoretically corroborated utilizing micromagnetic simulations. The second part of this thesis theoretically investigates a special spin transport mechanism in ferromagnetic thin films termed spin superfluidity. The main characteristic of this macroscopic state is the power-law dependence of the dissipated spin current in contrast to the exponential damping of spin waves, enabling low-loss long-range transport. The possible existence and the stability of the superfluidic transport in ferromagnetic thin films excited by spin-transfer torque in the presence of the intrinsic dipole-dipole interactions is reported for the first time. To provide indicators to prove the experimental realization of a spin superfluid the dependence on the excitation current is numerically analyzed. Three distinct regimes are obtained for both disabled and enabled dipole-dipole interactions, showing the generality of the investigated system. Both presented effects might open new paths for the technological application of magnonic devices in the future. / Die direkte Integration von magnon-spintronischen Bauteilen in moderne Technologien erfordert die Entwicklung von kurzwelligen Spinwellenquellen und verlustarmer Spinwellenleiter. In dieser Arbeit werden mögliche Lösungen für diese beiden Herausforderungen vorgestellt. Der erste Teil dieser Arbeit beschäftigt sich mit der nichtreziproken Spinwellenemission in magnetischen Doppellagen. Zwei Prototypsysteme werden theoretisch untersucht und durch experimentelle Ergebnisse untermauert: (i) ausgedehnte magnetische Doppellagen und (ii) mikrometer-große elliptische Doppellagen. Durch die dynamischen Dipol-Dipol-Wechselwirkungen wird eine Nichtreziprozität der Dispersionsrelation induziert. Diese wird mittels mikromagnetischer Simulationen und einer analytischen Theorie untersucht. Die nichtreziproke Frequenzverschiebung nimmt hierbei bei kleinen Wellenzahlen linear mit der Filmdicke zu. Die topologische Emission von Spinwellen wird in den mikrometer-großen elliptischen Doppellagen unter Verwendung von Röntgentransmissionsmikroskopie beobachtet und theoretisch unter Verwendung mikromagnetischer Simulationen bestätigt. Im zweiten Teil dieser Arbeit wird der spezielle Spintransport in ferromagnetischen dünnen Filmen untersucht, der als Spinsuprafluidität bekannt ist. Das Hauptmerkmal dieses makroskopischen Zustands ist die Abhängigkeit des dissipierten Spinstromes von der Propagationslänge als Potenzgesetz im Gegensatz zur exponentiellen Dämpfung von Spinwellen. Die Existenz und die Stabilität des suprafluiden Transportes in dünnen ferromagnetischen Filmen, angeregt durch einen spinpolarisierten Strom, in Gegenwart der intrinsischen Dipol-Dipol-Wechselwirkungen wird erstmals beschrieben. Um Hinweise für die experimentelle Realisierung der Spinsuprafluidität zu geben, wird die Abhängigkeit des Zustandes vom Anregungsstrom numerisch analysiert. Hierbei ergeben sich drei verschiedene Bereiche für den Fall vernachlässigter als auch aktivierter Dipol-Dipol-Wechselwirkung. Dies zeigt die Allgemeinheit des untersuchten Systems. Die beiden vorgestellten Effekte könnten in Zukunft neue Wege für die technologische Anwendung magnonischer Strukturen eröffnen.