Bibliografias temáticas / Quantum magnetisms

Índice

Artigos de revistas
Teses / dissertações
Livros
Capítulos de livros
Trabalhos de conferências
Relatórios de organizações

Literatura científica selecionada sobre o tema "Quantum magnetisms"

Autor: Grafiati

Publicado: 23 de novembro de 2024

Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos

Selecione um tipo de fonte:

Consulte a lista de atuais artigos, livros, teses, anais de congressos e outras fontes científicas relevantes para o tema "Quantum magnetisms".

Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.

Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.

Artigos de revistas sobre o assunto "Quantum magnetisms"

Stewart, A. M. "Gauge Invariant Magnetism". Australian Journal of Physics 50, n.º 6 (1997): 1061. http://dx.doi.org/10.1071/p97024.

Texto completo da fonte

Resumo:

An introduction is given to features of gauge invariance in classical and quantum mechanics that are of importance for magnetism in condensed matter systems. A version of quantum mechanics is described in which full electromagnetic gauge arbitrariness is displayed explicitly at every stage. The division of orbital magnetism into paramagnetism and diamagnetism is examined and it is shown that only by treating both of these on an equal footing can a gauge invariant treatment of magnetism be constructed.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Osborne, Ian S. "Cooperative quantum magnetism". Science 361, n.º 6404 (23 de agosto de 2018): 763.14–765. http://dx.doi.org/10.1126/science.361.6404.763-n.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Freeman, Arthur J., e Kohji Nakamura. "Computational quantum magnetism: Role of noncollinear magnetism". Journal of Magnetism and Magnetic Materials 321, n.º 7 (abril de 2009): 894–98. http://dx.doi.org/10.1016/j.jmmm.2008.11.107.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Slot, M. R., Y. Maximenko, P. M. Haney, S. Kim, D. T. Walkup, E. Strelcov, Son T. Le et al. "A quantum ruler for orbital magnetism in moiré quantum matter". Science 382, n.º 6666 (6 de outubro de 2023): 81–87. http://dx.doi.org/10.1126/science.adf2040.

Texto completo da fonte

Resumo:

For almost a century, magnetic oscillations have been a powerful “quantum ruler” for measuring Fermi surface topology. In this study, we used Landau-level spectroscopy to unravel the energy-resolved valley-contrasting orbital magnetism and large orbital magnetic susceptibility that contribute to the energies of Landau levels of twisted double-bilayer graphene. These orbital magnetism effects led to substantial deviations from the standard Onsager relation, which manifested as a breakdown in scaling of Landau-level orbits. These substantial magnetic responses emerged from the nontrivial quantum geometry of the electronic structure and the large length scale of the moiré lattice potential. Going beyond traditional measurements, Landau-level spectroscopy performed with a scanning tunneling microscope offers a complete quantum ruler that resolves the full energy dependence of orbital magnetic properties in moiré quantum matter.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Sachdev, Subir. "Quantum magnetism and criticality". Nature Physics 4, n.º 3 (março de 2008): 173–85. http://dx.doi.org/10.1038/nphys894.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Inosov, D. S. "Quantum magnetism in minerals". Advances in Physics 67, n.º 3 (3 de julho de 2018): 149–252. http://dx.doi.org/10.1080/00018732.2018.1571986.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Blackburn, Elizabeth. "Magnetism, superconductors, quantum systems". Neutron News 24, n.º 4 (outubro de 2013): 6–7. http://dx.doi.org/10.1080/10448632.2013.831644.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Castilla, G., S. Chakravarty e V. J. Emery. "Quantum Magnetism of CuGeO3". Physical Review Letters 75, n.º 9 (28 de agosto de 1995): 1823–26. http://dx.doi.org/10.1103/physrevlett.75.1823.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

KUZEMSKY, A. L. "QUANTUM PROTECTORATE AND MICROSCOPIC MODELS OF MAGNETISM". International Journal of Modern Physics B 16, n.º 05 (20 de fevereiro de 2002): 803–23. http://dx.doi.org/10.1142/s0217979202010002.

Texto completo da fonte

Resumo:

Some physical implications involved in a new concept, termed the "quantum protectorate" (QP), are developed and discussed. This is done by considering the idea of quantum protectorate in the context of quantum theory of magnetism. It is suggested that the difficulties in the formulation of quantum theory of magnetism at the microscopic level, that are related to the choice of relevant models, can be understood better in the light of the QP concept. We argue that the difficulties in the formulation of adequate microscopic models of electron and magnetic properties of materials are intimately related to dual, itinerant and localized behaviour of electrons. We formulate a criterion of what basic picture describes best this dual behaviour. The main suggestion is that quasi-particle excitation spectra might provide distinctive signatures and good criteria for the appropriate choice of the relevant model.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Georgii, Robert, e Klaus-Dieter Liss. "Quantum Beams for New Aspects in Magnetic Materials and Magnetism". Quantum Beam Science 3, n.º 4 (25 de novembro de 2019): 22. http://dx.doi.org/10.3390/qubs3040022.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Mais fontes

Teses / dissertações sobre o assunto "Quantum magnetisms"

Catalano, Alberto Giuseppe. "Understanding and exploiting non-local effects in quantum spin chains". Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAF022.

Texto completo da fonte

Resumo:

À l'aube de la seconde révolution quantique, comprendre et exploiter les phénomènes résultant de l'interaction entre la non-localité intrinsèque de la mécanique quantique et les interactions purement non-locales est d'une importance cruciale pour le développement de nouvelles technologies quantiques. Dans cette thèse, nous nous concentrerons principalement sur les effets non-locaux introduits par la frustration topologique (FT), une forme de frustration faible qui a été introduite pour la première fois dans le contexte des chaînes de spins quantiques antiferromagnétiques en appliquant les conditions aux limites frustrées, réalisées comme une combinaison de conditions aux limites périodiques et d'un nombre impair de spins. Notre objectif est double. D'une part, nous améliorerons la compréhension théorique des phases topologiquement frustrées. Au-delà de ces implications théoriques, ce travail démontrera que les chaînes de spins FT présentent un potentiel technologique convaincant, les proposant comme des candidats compétitifs pour le développement de batteries quantiques robustes et efficaces
At the verge of the second quantum revolution, understanding and exploiting the phenomena resulting from the interplay between the intrinsic non-locality of quantum mechanics and purely non-local interactions is of crucial importance for the development of novel quantum technologies. In this thesis, we will mostly focus on the non-local effects introduced by topological frustration (TF), a form of weak frustration that was first introduced in the context of antiferromagnetic quantum spin chains by applying the so called frustrated boundary conditions, realized as a combination of periodic boundary conditions and odd number of spins. Our goal is double. From one side, we will further improve the theoretical understanding of topologically frustrated phases. Beyond these theoretical implications, this work will demonstrate that TF spin chains exhibit compelling technological potential, proposing them as competitive candidates for the development of robust and efficient quantum batteries

Estilos ABNT, Harvard, Vancouver, APA, etc.

Joshi, Darshan Gajanan. "Magnetic quantum phase transitions: 1/d expansion, bond-operator theory, and coupled-dimer magnets". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-198634.

Texto completo da fonte

Resumo:

In the study of strongly interacting condensed-matter systems controlled microscopic theories hold a key position. Spin-wave theory, large-N expansion, and $epsilon$-expansion are some of the few successful cornerstones. In this doctoral thesis work, we have developed a novel large-$d$ expansion method, $d$ being the spatial dimension, to study model Hamiltonians hosting a quantum phase transition between a paramagnet and a magnetically ordered phase. A highlight of this technique is that it can consistently describe the entire phase diagram of the above mentioned models, including the quantum critical point. Note that most analytical techniques either efficiently describe only one of the phases or suffer from divergences near the critical point. The idea of large-$d$ formalism is that in this limit, non-local fluctuations become unimportant and that a suitable product state delivers exact expectation values for local observables, with corrections being suppressed in powers of $1/d$. It turns out that, due to momentum summation properties of the interaction structure factor, all diagrams are suppressed in powers of $1/d$ leading to an analytic expansion. We have demonstrated this method in two important systems namely, the coupled-dimer magnets and the transverse-field Ising model. Coupled-dimer magnets are Heisenberg spin systems with two spins, coupled by intra-dimer antiferromagnetic interaction, per crystallographic unit cell (dimer). In turn, spins from neighboring dimers interact via some inter-dimer interaction. A quantum paramagnet is realized for a dominant intra-dimer interaction, while a magnetically ordered phase exists for a dominant (or of the same order as intra-dimer interaction) inter-dimer interaction. These two phases are connected by a quantum phase transition, which is in the Heisenberg O(3) universality class. Microscopic analytical theories to study such systems have been restricted to either only one of the phases or involve uncontrolled approximations. Using a non-linear bond-operator theory for spins with S=$1/2$, we have calculated the $1/d$ expansion of static and dynamic observables for coupled dimers on a hypercubic lattice at zero temperature. Analyticity of the $1/d$ expansion, even at the critical point, is ensured by correctly identifying suitable observables using the mean-field critical exponents. This method yields gapless excitation modes in the continuous symmetry broken phase, as required by Goldstone\'s theorem. In appropriate limits, our results match with perturbation expansion in small ratio of inter-dimer and intra-dimer coupling, performed using continuous unitary transformations, as well as the spin-wave theory for spin-$1/2$ in arbitrary dimensions. We also discuss the Brueckner approach, which relies on small quasiparticle density, and derive the same $1/d$ expansion for the dispersion relation in the disordered phase. Another success of our work is in describing the amplitude (Higgs) mode in coupled-dimer magnets. Our novel method establishes the popular bond-operator theory as a controlled approach. In $d=2$, the results from our calculations are in qualitative agreement with the quantum Monte Carlo study of the square-lattice bilayer Heisenberg AF spin-$1/2$ model. In particular, our results are useful to identify the amplitude (Higgs) mode in the QMC data. The ideas of large-$d$ are also successfully applied to the transverse-field Ising model on a hypercubic lattice. Similar to bond operators, we have introduced auxiliary Bosonsic operators to set up our method in this case. We have also discussed briefly the bilayer Kitaev model, constructed by antiferromagnetically coupling two layers of the Kitaev model on a honeycomb lattice. In this case, we investigate the dimer quantum paramagnetic phase, realized in the strong inter-layer coupling limit. Using bond-operator theory, we calculate the mode dispersion in this phase, within the harmonic approximation. We also conjecture a zero-temperature phase diagram for this model.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Rezakhanlou, Karen. "Orbital magnetism and quantum chaos /". [S.l.] : [s.n.], 1995. http://library.epfl.ch/theses/?nr=1312.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Brambleby, Jamie. "Quantum magnetism in coordination polymers". Thesis, University of Warwick, 2018. http://wrap.warwick.ac.uk/111284/.

Texto completo da fonte

Resumo:

This thesis presents an experimental and theoretical examination of five polymeric quantum magnets. The first of these is Cu(pyrazine)(glycinate)ClO4, an exchange-coupled spin-dimer system that undergoes a powerful and continuous magnetocaloric effect (MCE) in a rapidly changing magnetic field H. The evolution of the sample temperature T with H must be accounted for in order to reconcile an apparent discrepancy between the results of magnetometry measurements performed in quasistatic and pulsed magnetic fields, and the MCE is likely to be an important consideration for pulsed-field experiments performed on similar insulating materials. Heat capacity measurements of Cu(pyrazine)(glycinate)ClO4 are perturbed by zero-point fluctuations for T > 400 mK, and these data further suggest that this system exhibits possible two-dimensional universal behaviour. The results of single crystal x-ray diffraction measurements of a second material [H2F]2[NiF2(3-fluoropyridine)4]3[SbF6]2 at 100 K indicate that the Ni2+ ions of this complex are arranged on the vertices of a two-dimensional kagome lattice, wherein the spin S = 1 ions are bridged via charge-assisted Ni-F· · · H-F-H· · · F-Ni linkages. However, a density-functional theory study indicates that a positional disorder of the H2F+ moieties within these bridges suppresses the intraplane spin-exchange interactions. Powder muon spin-rotation measurements imply that the system is paramagnetic for T > 19 mK, while polycrystalline electron spin-resonance (ESR), magnetization M(H), and heat capacity experiments together indicate that the unixial and rhombohedral single-ion anisotropy of the Ni2+ ions are approximately D/kb = 8.3(4) K and E/kb = 1.2(3) K respectively. Lastly, neutron powder diffraction measurements of three isotructural compounds [M(HF2)(pyrazine)2]SbF6 (M = Cu2+, Ni2+ or Co2+) reveal that each system is tetragonal (P4/nmm) and that the spin-exchange interactions facilitated by the pyrazine (Jpyz) and bifluoride (Jfhf) ligands are antiferromagnetic. The Cu2+ congener is a quasi-two-dimensional Heisenberg S = 1/2 antiferromagnet, which displays an ordered moment of 0.6(1)μb per ion that is reduced from its paramagnetic value by quantum fluctuations. For the S = 1 Ni2+ complex, powder M(H) measurements suggest that D has an easy-plane character while inelastic neutron scattering experiments determine D/kb = 13.3(3) K, Jfhf/kb = 10.4(3) K and Jpyz/kb = 1.4(2) K. The S = 3/2 Co2+ system adopts an Ising-like antiferromagnetic ground state below 7.1(1) K, and its magnetic properties are parameterized with an effective spin-1/2 Hamiltonian for T < 50 K.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Aguilà, Avilés David. "Design, synthesis and study of coordination complexes for quantum computing". Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/123544.

Texto completo da fonte

Resumo:

This thesis presents different strategies for the design of molecular complexes with the requirements to be used as two-qubit quantum gates. The approaches followed towards the preparation of potential qubit systems have been carried out focusing on the synthesis of ligands with β-diketone coordination units, which are very versatile for the design of metallocluster assemblies. One of the main advantages of using this kind of ligands is that they can be easily prepared through simple Claisen condensation, providing different combinations and possibilities for the addition of big variety of donor atoms and pockets. Each ligand has been designed for the preparation of predefined magnetic coordination complexes that can fulfill the conditions of a two-qubit molecular quantum gate. The different complexes synthesized within this thesis can be defined in two different categories: Molecular pairs of well-defined and weakly coupled metal clusters, and complexes of two dissimilar and weakly coupled anisotropic metal ions. In addition, the use of the designed ligands for the preparation of metallo-helicates has been also carried out. The description and study of their helicoidal structure is also shown, using the ligand H4L1 with trivalent and tetravalent metal ions like FeIII, GaIII or UIV. - Molecules featuring two weakly coupled clusters: The approach is based on the design of molecules featuring two well defined coordination clusters that could represent ideal systems for realizing two-qubit quantum gates, as long as each cluster exhibits the appropriate spin properties. Two different ligand-based strategies have been followed for the preparation of such molecular pairs of well-defined metal clusters. The first one is based on the design of poly-β-diketone ligands exhibiting two groups of coordination pockets, which serve to aggregate metals in close proximity. Following this approach, the ligand is responsible for having metals grouped into two clusters, as well as for keeping each metal group together within each subsystem. The structural characteristics of H4L1 provides the requirements for the construction of this kind of clusters, since it might align and separate metals into two dimetallic entities. The goal has been achieved by using the deprotonated ligand that organizes the metals in two groups within molecular linear arrays, saturating the equatorial positions. Compounds with NiII, CuII and CoII metal ions are described and studied. The second strategy is based on the preparation of poly-β-diketone ligands with an additional X donor atom in the middle for acting as a “template” for the aggregation of metals into linear clusters, further linked as molecular pairs by auxiliary ligands Organic ligands like H4L2 or H2L3 fulfill the requirements to aggregate closely spaced metals, which can be then used as building blocks to be linked into molecular pairs by other bifunctional external ligands. An example using CoII is described and studied. - Dinuclear complexes of anisotropic metal ions: The synthesis of complexes of two dissimilar and weakly coupled lanthanides has been used as approach for the construction of molecular prototypes of CNOT quantum gates. The ligand-based strategy considers the design of non-symmetric ligands as a possible way of having two inequivalent lanthanide qubits within a molecule. The ligand H3L4 exhibits a collection of donor groups disposed to favor the aggregation of two metals in different coordination environments. The use of lanthanide ions are good candidates for encoding quantum information following such approach, since they can exhibit strong anisotropy and very well isolated ground state doublets ±mJ (effective S = ½). In addition, lanthanide ions have been proved to have spin states with long decoherence, with T2 timescales that can reach values up to 7 μs.[41] A detailed study of a vast number of dinuclear homo- and heterometallic lanthanide coordination complexes is exposed, including an exhaustive study for some of them to prove their possibilities as CNOT and √SWAP quantum gates.
El trabajo realizado en esta tesis doctoral se basa en el diseño, la síntesis y el estudio de complejos de coordinación, centrándose en la comprensión de sus propiedades magnéticas y la posibilidad de su aplicación en la computación cuántica. Para el diseño de estos materiales moleculares, tres diferentes propuestas han sido llevadas a cabo. En primer lugar, se han desarrollado ligandos capaces de agregar metales paramagnéticos en dos grupos diferentes, definiendo de esta manera los dos posibles bits cuánticos de una puerta lógica. Complejos de coordinación homo- y heterometálicos con NiII, CoII y CuII han sido sintetizados y caracterizados para tal efecto. La segunda estrategia seguida ha estado centrada en el diseño de complejos de coordinación lineales para su posterior ensamblaje en parejas de compuestos. Se han desarrollado ligandos que favorezcan la complejación de este tipo de topología, obteniéndose un compuesto de CoII con las propiedades estructurales idóneas para su ensamblaje. Utilizando el ligando bifuncional 4.4’-bipiridina, se ha podido unir dos entidades [Co4] obteniendo así otro prototipo de “parejas moleculares”. La tercera estrategia se ha centrado en el diseño de moléculas asimétricas para facilitar la definición de cada bit cuántico dentro de la entidad molecular. Para ello, se ha sintetizado un ligando no simétrico, que ha sido utilizado para obtener complejos dinucleares homo- y heterometálicos de iones lantánido. Se ha obtenido compuestos con todos los elementos de la serie de los lantánidos. Su estudio magnético y estructural ha mostrado que los dos centros metálicos de estas entidades moleculares son distintos, lo que ha permitido definir el espín de cada ion lantánido como un bit cuántico. El estudio magnético a muy bajas temperaturas de un compuesto de dos átomos de terbio(III), por ejemplo, ha permitido definir dos puertas lógicas: la CNOT y la √SWAP. Utilizando el espectro de energías de los estados magnéticos de la molécula, se han observado las transiciones entre dichos estados en relación a las dos operaciones lógicas.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Steele, Andrew J. "Quantum magnetism probed with muon-spin relaxation". Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:030d7e91-f38e-433f-9539-652b0f4996cc.

Texto completo da fonte

Resumo:

This thesis presents the results of muon-spin relaxation (µ⁺SR) studies into magnetic materials, and demonstrates how these results can be exploited to quantify the materials’ low moments and reduced dimensionality. Dipole-field simulations, traditionally used to estimate likely muon sites within a crystal structure, are described. A novel Bayesian approach is introduced which allows bounds to be extracted on magnetic moment sizes and magnetic structures—previously very difficult using µ⁺SR—based on reasonable assumptions about positions in which muons are likely to stop. The simulations are introduced along with relevant theory, and MµCalc, a platform-independent program which I have developed for performing the calculations is described. The magnetic ground states of the isostructural double perovskites Ba₂NaOsO₆ and Ba₂LiOsO₆ are investigated with µ⁺SR. In Ba₂NaOsO₆ long-range magnetic order is detected via the onset of a spontaneous muon-spin precession signal below T_c = 7.2(2) K, while in Ba₂LiOsO₆ a static but spatially-disordered internal field is found below 8 K. Bayesian analysis is used to show that the magnetic ground state in Ba₂NaOsO₆ is most likely to be low-moment (˜ 0.2µ_B) ferromagnetism and not canted antiferromagnetism. Ba₂LiOsO₆ is antiferromagnetic and a spin-flop transition is found at 5.5 T. A reduced osmium moment is common to both compounds, probably arising from a combination of spin–orbit coupling and frustration. Results are also presented from µ⁺SR investigations concerning magnetic ordering in several families of layered, quasi–two-dimensional molecular antiferromagnets based on transition metal ions such as S = ½ Cu²⁺ bridged with organic ligands such as pyrazine. µ⁺SR allows us to identify ordering temperatures and study the critical behaviour close to T_N , which is difficult using conventional probes. Combining this with measurements of in-plane magnetic exchange J and predictions from quantum Monte Carlo simulations allows assessment of the degree of isolation of the 2D layers through estimates of the effective inter-layer exchange coupling and in-layer correlation lengths at T_N. Likely metal-ion moment sizes and muon stopping sites in these materials are identified, based on probabilistic analysis of dipole-fields and of muon–fluorine dipole–dipole coupling in fluorinated materials.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Fiore, Mosca Dario. "Quantum magnetism in relativistic osmates from first principles". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17982/.

Texto completo da fonte

Resumo:

The interplay between electron correlation, local distortions and Spin Orbit Coupling is one of the most attractive phenomena in condensed matter Physics and have stimulated much attention in the last decade. In Osmates double perovskites the coupling between electronic, structural and orbital degrees of freedom leads to the formation of an unconventional magnetic phase, whose precise origin and characteristics are still not understood. In particular strong Spin Orbit Coupling effect is believed to occur and have a crucial role in enhancing multipolar exchange interactions in a fashion similar to the more studied 4f electron systems. In this thesis, by means of first principles calculations, we study the structural, electronic and magnetic proprieties of the Mott insulating Ba2NaOsO6 with Osmium in 5d1 electron configuration within the fully relativistic Density Functional Theory plus on site Hubbard U (DFT + U) scheme. We find that the system is subjected to local symmetry breaking and that the magnetic ground state is strongly dependent on the on site Coulomb interaction. Furthermore, by mapping the energy onto a Pseudospin Hamiltonian, we are capable to prove that quadrupolar and octupolar exchanges play a significant role. We repeated the study for Ba2CaOsO6 with Os in 5d2 electronic configuration as a preliminary step for understanding if phase transitions are possible when Ba2NaOsO6 is doped.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Bühler, Adam [Verfasser]. "Quantum Simulator for Spin-Orbital Magnetism / Adam Bühler". München : Verlag Dr. Hut, 2016. http://d-nb.info/1097818373/34.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Lorenz, Wolfram. "On the Spin-Dynamics of the Quasi-One-Dimensional, Frustrated Quantum Magnet Li2CuO2". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-71010.

Texto completo da fonte

Resumo:

Die magnetischen Eigenschaften von Li2CuO2 sind seit mehr als zwei Jahrzehnten Gegenstand theoretischen und experimentellen Interesses. Über die genaue Natur der magnetischen Wechselwirkungen in diesem Isolator konnte jedoch keine Einigkeit erzielt werden. Während das Material von Seiten theoretischer Untersuchungen als quasi-eindimensionaler Magnet mit starken ferromagnetischen Kopplungen entlang der Kette verstanden wurde, legten experimentelle Studien dominierende dreidimensionale Zwischenkettenkopplungen nahe. Im Rahmen dieser Dissertation werden auf der Grundlage von Untersuchungen des magnetischen Anregungsspektrums mittels inelastischer Neutronenstreuung und dessen Analyse innerhalb eines Spinwellenmodels die führenden magnetischen Wechselwirkungen in Li2CuO2 bestimmt. Es wird zweifelsfrei nachgewiesen, dass das Material eine quasi-eindimensionale Spinkettenverbindung darstellt. Insbesondere kann die Konkurrenz von ferro- und antiferromagnetischen Wechselwirkungen entlang der Ketten nachgewiesen werden. Die Anwendbarkeit einer Spinwellenanalyse dieses niedrigdimensionalen Spin-1=2 Systems wird gezeigt. Das magnetische Phasendiagramm wird mittels Messungen von spezifischer Wärme, thermischer Ausdehnung und Magnetostriktion sowie der Magnetisierung in statischen und gepulsten Magnetfeldern untersucht und im Bezug auf die Austauschwechselwirkungen diskutiert. Aufgrund seiner einfachen kristallographischen und magnetischen Struktur stellt Li2CuO2 ein potentiell wertvolles Modellsystem in der Klasse der Spinkettenverbindungen mit konkurrierenden ferro- und antiferromagnetischen Wechselwirkungen dar
The magnetic properties of Li2CuO2 have attracted interest since more than two decades, both in theory and experiment. Despite these efforts, the precise nature of the magnetic interactions in this insulator remained an issue of controversial debate. From theoretical studies, the compound was understood as a quasi-one-dimensional magnet with strong ferromagnetic interactions along the chain, while in contrast, experimentally studies suggested dominant three-dimensional inter-chain interactions. In this thesis, the leading magnetic exchange interactions of Li2CuO2 are determined on the basis of a detailed inelastic neutron scattering study of the magnetic excitation spectrum, analyzed within spin-wave theory. It is unequivocally shown, that the material represents a quasi-one-dimensional spin-chain compound. In particular, the competition of ferro- and antiferromagnetic interactions in the chain has been evidenced. The applicability of a spin-wave model for analysis of this low-dimensional spin-1=2 system is shown. The magnetic phase diagram of Li2CuO2 is studied by specific heat, thermal expansion and magnetostriction measurements as well as magnetization measurements in both static and pulsed magnetic fifields. The phase diagram is discussed with respect to the exchange interactions. With its simple crystallographic and magnetic structure, Li2CuO2 may serve as a worthwhile model system in the class of spin-chain compounds with competing ferromagnetic and antiferromagnetic interactions

Estilos ABNT, Harvard, Vancouver, APA, etc.

Morris, Richard. "Studies towards quantum magnonics". Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:89784b64-de31-457f-b9b2-54125c862632.

Texto completo da fonte

Resumo:

This thesis reports on recent results which pave the way for future experiments in the emerging field of quantum magnonics. Chapter 1 presents a brief outline of the field of magnonics, which provides the context in which quantum magnonics has begun to develop. Chapter 2 provides an introduction to the theory of spin waves, which is necessary to understand the experiments reported in the thesis. In Chapter 3, the experimental methods and materials used to carry out the investigations in the thesis are described. Chapter 4 describes the coupling of resonant magnon modes in a sphere of yttrium-iron garnet to photon modes in a coplanar-waveguide resonator. Strong coupling is achieved to multiple magnon modes, and a theoretical model is used to identify the magnon modes which couple most strongly to the photon mode. In Chapter 5, the behaviour of propagating magnon modes is investigated in a waveguide formed from a thin film of yttrium-iron garnet. Two different configurations are investigated supporting different types of propagating mode, namely backward-volume and surface spin waves. Simulations are performed which reproduce the main features of the data. Chapter 6 characterises the effect of the gadolinium-gallium garnet substrate on propagating spin waves. The magnitude of this effect is dependent on both the orientation and temperature of the sample. Finally, Chapter 7 provides a short summary of the results of the thesis, and speculates on how they may inform future work in the field.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Mais fontes

Livros sobre o assunto "Quantum magnetisms"

Barbara, Bernard, Yosef Imry, G. Sawatzky e P. C. E. Stamp, eds. Quantum Magnetism. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-8512-3.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Schollwöck, Ulrich, Johannes Richter, Damian J. J. Farnell e Raymod F. Bishop, eds. Quantum Magnetism. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/b96825.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Bernard, Barbara, ed. Quantum magnetism. Dordrecht: Springer, 2008.

Encontre o texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Yoshihito, Miyako, Takayama H. 1945- e Miyashita S. 1954-, eds. Frontiers in magnetism: Metallic magnetism, glassy magnetism, quantum magnetism. Tokyo: Physical Society of Japan, 2000.

Encontre o texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

White, Robert M. Quantum Theory of Magnetism. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-69025-2.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Nolting, Wolfgang, e Anupuru Ramakanth. Quantum Theory of Magnetism. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-85416-6.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Anupuru, Ramakanth, e SpringerLink (Online service), eds. Quantum theory of magnetism. Heidelberg: Springer, 2009.

Encontre o texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Auerbach, Assa. Interacting Electrons and Quantum Magnetism. New York, NY: Springer New York, 1994. http://dx.doi.org/10.1007/978-1-4612-0869-3.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Auerbach, Assa. Interacting electrons and quantum magnetism. New York: Springer-Verlag, 1994.

Encontre o texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Viola Kusminskiy, Silvia. Quantum Magnetism, Spin Waves, and Optical Cavities. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-13345-0.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Mais fontes

Capítulos de livros sobre o assunto "Quantum magnetisms"

Parkinson, John B., e Damian J. J. Farnell. "Quantum Magnetism". In An Introduction to Quantum Spin Systems, 135–52. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-13290-2_11.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Aeppli, Gabriel, e Philip Stamp. "Quantum Magnetism". In Handbook of Magnetism and Magnetic Materials, 261–80. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63210-6_5.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Aeppli, Gabriel, e Philip Stamp. "Quantum Magnetism". In Handbook of Magnetism and Magnetic Materials, 1–20. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63101-7_5-1.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Schnack, Jürgen. "Molecular magnetism". In Quantum Magnetism, 155–94. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/bfb0119593.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Mikeska, Hans-Jürgen, e Alexei K. Kolezhuk. "One-dimensional magnetism". In Quantum Magnetism, 1–83. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/bfb0119591.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Richter, Johannes, Jörg Schulenburg e Andreas Honecker. "Quantum magnetism in two dimensions: From semi-classical Néel order to magnetic disorder". In Quantum Magnetism, 85–153. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/bfb0119592.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Ivanov, Nedko B., e Diptiman Sen. "Spin wave analysis of heisenberg magnets in restricted geometries". In Quantum Magnetism, 195–226. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/bfb0119594.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Laflorencie, Nicolas, e Didier Poilblanc. "Simulations of pure and doped low-dimensional spin-1/2 gapped systems". In Quantum Magnetism, 227–52. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/bfb0119595.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Cabra, Daniel C., e Pierre Pujol. "Field-theoretical methods in quantum magnetism". In Quantum Magnetism, 253–305. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/bfb0119596.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Farnell, Damian J. J., e Raymond F. Bishop. "The coupled cluster method applied to quantum magnetism". In Quantum Magnetism, 307–48. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/bfb0119597.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Trabalhos de conferências sobre o assunto "Quantum magnetisms"

Gavryusev, Vladislav, Luca Guariento, Veronica Giardini, Andrea Fantini, Shawn Storm, Jacopo Catani, Massimo Inguscio, Leonardo Fallani e Giacomo Cappellini. "A New Programmable Quantum Simulator with Strontium Rydberg Atoms in Optical Tweezer Arrays". In Quantum 2.0, QTh2A.2. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/quantum.2024.qth2a.2.

Texto completo da fonte

Resumo:

Ultra-cold interacting Rydberg Strontium atoms trapped in reconfigurable optical tweezers can simulate quantum magnetism and energy transport. I will present our setup and planned capabilities, including electric field control, 3D traps and single site addressing.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Oliveira, Samuel L., e Stephen C. Rand. "Optical magnetism". In 2007 Quantum Electronics and Laser Science Conference. IEEE, 2007. http://dx.doi.org/10.1109/qels.2007.4431630.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Kimel, A. V., A. Kirilyuk e Th Rasing. "Femtosecond opto-magnetism". In 2007 Quantum Electronics and Laser Science Conference. IEEE, 2007. http://dx.doi.org/10.1109/qels.2007.4431810.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Haas, Stephan, Adolfo Avella e Ferdinando Mancini. "Quantum Magnetism, Nanomagnets and Entanglement". In LECTURES ON THE PHYSICS OF STRONGLY CORRELATED SYSTEMS XII: Twelfth Training Course in the Physics of Strongly Correlated Systems. AIP, 2008. http://dx.doi.org/10.1063/1.2940446.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Degen, Christian, e Pol Welter. "Quantum microscopy of nanoscale magnetism". In Spintronics XIV, editado por Henri-Jean M. Drouhin, Jean-Eric Wegrowe e Manijeh Razeghi. SPIE, 2021. http://dx.doi.org/10.1117/12.2597939.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Fisher, William M., e Stephen C. Rand. "Parametric Optical Magnetism and the Complex Mathieu Equation". In International Quantum Electronics Conference. Washington, D.C.: OSA, 2009. http://dx.doi.org/10.1364/iqec.2009.ituf3.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Majedi, Hamed. "Nonlinear Optics and Optomagnetics in Quantum Materials". In Nonlinear Optics. Washington, D.C.: Optica Publishing Group, 2023. http://dx.doi.org/10.1364/nlo.2023.tu2b.5.

Texto completo da fonte

Resumo:

The main physics of nonlinear optical properties of two-dimensional Dirac materials with a specific e xample of graphene is discussed. Our experimental work on characterization of the temporal and spectral properties of Kerr coefficient in graphene is presented. Theories of Optomagnetism in graphene and newly proposed microwave opto-magnetism in superconductors are elaborated.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Venkataramana, Bonu, A. Das, Manas Sardar, S. Dhara e A. K. Tyagi. "Intrinsic high magnetism in SnO2 quantum dots". In SOLID STATE PHYSICS: Proceedings of the 58th DAE Solid State Physics Symposium 2013. AIP Publishing LLC, 2014. http://dx.doi.org/10.1063/1.4872649.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Sakai, Tôru, e Kiyomi Okamoto. "Exotic Magnetism of the Quantum Spin Nanotubes". In Proceedings of the International Symposium on Science Explored by Ultra Slow Muon (USM2013). Journal of the Physical Society of Japan, 2014. http://dx.doi.org/10.7566/jpscp.2.010208.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Porras, D., e J. I. Cirac. "Simulation of quantum magnetism with trapped ions". In Moscow, Russia, editado por Yuri I. Ozhigov. SPIE, 2005. http://dx.doi.org/10.1117/12.620491.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Relatórios de organizações sobre o assunto "Quantum magnetisms"

Scheie, Allen. Quantum magnetism, philosophy, and neutron scattering. Office of Scientific and Technical Information (OSTI), maio de 2024. http://dx.doi.org/10.2172/2367470.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Lee, Minhyea. Transport Studies of Quantum Magnetism: Physics and Methods. Office of Scientific and Technical Information (OSTI), março de 2017. http://dx.doi.org/10.2172/1349030.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Li, Yi, Hsiang-hsuan Hung, Zi Cai, Congjun Wu, Wei-Cheng Li e Dan Arovas. Novel Quantum States with Exotic Spin Properties - Unconventional Generalization of Magnetism. Fort Belvoir, VA: Defense Technical Information Center, dezembro de 2011. http://dx.doi.org/10.21236/ada582118.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Sharpe, Aaron. Emergent Quantum Magnetism and Cryogenic Spin-Memory in Twisted Bilayer Graphene. Office of Scientific and Technical Information (OSTI), novembro de 2023. http://dx.doi.org/10.2172/2430210.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Oferecemos descontos em todos os planos premium para autores cujas obras estão incluídas em seleções literárias temáticas. Contate-nos para obter um código promocional único!