Готові списки джерел за темами / Electronic Structure - Novel Magnetic Systems

Добірка наукової літератури з теми "Electronic Structure - Novel Magnetic Systems"

Автор: Grafiati

Опубліковано: 7 вересня 2023

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Статті в журналах з теми "Electronic Structure - Novel Magnetic Systems"

Grechnev, G. E., A. S. Panfilov, A. V. Fedorchenko, V. A. Desnenko, I. P. Zhuravleva, S. L. Gnatchenko, D. A. Chareev, O. S. Volkova, and A. N. Vasiliev. "Electronic Structure and Magnetism of Fe-based Superconductors." Ukrainian Journal of Physics 57, no. 2 (February 15, 2012): 171. http://dx.doi.org/10.15407/ujpe57.2.171.

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Ab initio calculations of the electronic structures are carried out for the novel FeSe1–xTex superconductors to explain the experimentally found anomalous magnetic properties in the normal state. The calculations have shown that FeSe1–xTex systems are close to a magnetic instability with dominating enhanced spin paramagnetism. The magnetic susceptibility is found to increase gradually with the Te content. The temperature dependences of the magnetic susceptibility χ and its anisotropy ∆ χ = χ║ – χ┴ are investigated for FeSe, and a growth of the susceptibility with the temperature is revealed in the temperature range 4.2–300 K. For FeTe, a substantial increase of χ under pressure is found. The calculated paramagnetic susceptibility exhibits a strong dependence on the unit cell volume V and especially the height of chalcogen species from the Fe plane. The calculations have explained the experimental data on χ(T) and χ(P) for FeSe and FeTe, respectively.

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Perez de Lara, David. "Hybrid Superconducting/Magnetic Multifunctional Devices in Two-Dimensional Systems." Physchem 2, no. 4 (November 25, 2022): 347–56. http://dx.doi.org/10.3390/physchem2040025.

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The emergence of unexpected properties in two-dimensional materials, interfaces, and nanostructured materials opens an exciting framework for exploring new devices and applications. Recent advances in materials design and the nano structurization of novel, low-dimensional materials, surfaces, and interfaces offer a novel playground to design efficient multifunctional materials-based devices. Low-dimensional materials exhibit peculiarities in their electronic, magnetic, and optical properties, changing with respect to the bulk when they are layered down to a single layer, in addition to their high tunability. Their crystal structure and chemical bonds lead to inherent unique mechanical properties. The fabrication of van der Waals heterostructures by stacking materials with different properties, the better control of interfaces, and the tunability of the physical properties by mechanical strain, and chemical and electronic doping allow for the exploration of multifunctional devices with superconducting, magnetic, and optical properties and unprecedented degrees of freedom in terms of fabrication and tunability.

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Kadioglu, Yelda, Ilkay Ozdemir, Olcay Üzengi Aktürk, Gökhan Gökoğlu, Ümit Akıncı, and Ethem Aktürk. "Tuning the electronic structure of RhX3 (X = Cl, Br, I) nonmagnetic monolayers: effects of charge-injection and external strain." Physical Chemistry Chemical Physics 22, no. 8 (2020): 4561–73. http://dx.doi.org/10.1039/c9cp06240h.

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The electronic and magnetic nature of novel semiconducting RhX₃ (X = Cl, Br, I) monolayer systems, which are dynamically and thermally stable, can be tuned by electrical and mechanical modifications.

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KAN, ERJUN, ZHENYU LI, and JINLONG YANG. "MAGNETISM IN GRAPHENE SYSTEMS." Nano 03, no. 06 (December 2008): 433–42. http://dx.doi.org/10.1142/s1793292008001350.

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Graphene has attracted great interest in materials science, owing to its novel electronic structures. Recently, magnetism discovered in graphene-based systems has opened up the possibility of their spintronics application. This paper provides a comprehensive review of the magnetic behaviors and electronic structures of graphene systems, including two-dimensional graphene, one-dimensional graphene nanoribbons, and zero-dimensional graphene nanoclusters. Theoretical research suggests that such metal-free magnetism mainly comes from the localized states or edges states. By applying an external electric field, or by chemical modification, we can turn the zigzag nanoribbon systems into half metal, thus obtaining a perfect spin filter.

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Valenzuela, Raúl. "Novel Applications of Ferrites." Physics Research International 2012 (March 15, 2012): 1–9. http://dx.doi.org/10.1155/2012/591839.

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The applications of ferrimagnetic oxides, or ferrites, in the last 10 years are reviewed, including thin films and nanoparticles. The general features of the three basic crystal systems and their magnetic structures are briefly discussed, followed by the most interesting applications in electronic circuits as inductors, in high-frequency systems, in power delivering devices, in electromagnetic interference suppression, and in biotechnology. As the field is considerably large, an effort has been made to include the original references discussing each particular application on a more detailed manner.

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Ding, Dawei, Dawei Li, Jing Xia, and Zhuang Li. "Novel optimization strategies for isolation structure design in MIMO systems." IEICE Electronics Express 17, no. 8 (2020): 20200006. http://dx.doi.org/10.1587/elex.17.20200006.

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Zhang, Zijia, Jun Liu, and Yansong Li. "Design and Analysis of a Multi-Input Multi-Output System for High Power Based on Improved Magnetic Coupling Structure." Energies 15, no. 5 (February 24, 2022): 1684. http://dx.doi.org/10.3390/en15051684.

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Conventional inductive contactless power transfer (ICPT) systems have only one energy transmission path, which makes it challenging to meet the power transmission requirements of high-power and reliability. This study proposes a novel multiple-input multiple-output (MIMO) ICPT system. The three-dimensional finite element analysis tool COMSOL is utilised to study various magnetic coupling structures, analyse the influence of cross-coupling between coils on the same side, design the circuit based on this, propose a parameter configuration method for resonance compensation, and, finally, build an experimental platform with small magnetic coupling structures for single-input single-output systems (SISO) and MIMO systems. The results indicate that the co-directional connection of the coils of the E-shaped and UE-shaped magnetic coupling structures has a strengthening effect on the secondary side coupling. The magnetic coupling structure of the E-shaped iron core exhibits the best transmission performance. The transmission power of the MIMO system with the E-shaped magnetic coupling structure as the core device is significantly improved. In addition, the output power is unchanged after a secondary side fault, which verifies the accuracy of the proposed method.

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Ying, Yu, Ke Xu, Guang-Yuan Si, and Ji-Zhong Zhao. "Simulation and Experiment Study of Chain Aggregate Structure in Magnetic Fluid." Integrated Ferroelectrics 201, no. 1 (September 2, 2019): 110–19. http://dx.doi.org/10.1080/10584587.2019.1668695.

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Magnetic fluid is a novel magnetic functional material. The magneto-optical properties are displayed due to the tunability. In the paper, the material characterization was studied theoretically and experimentally. In the simulation, a rod-like magnetic nanoparticle model was used to simulate the motion of the magnetic particles. In the experiment, an experimental setup was designed to observe the change of the microstructure. The results showed that the magnetic particles can be aggregated to form several magnetic chains when the applied magnetic field exceeded 100 Oe. The novel magneto-optical device exhibits advantages of low cost, small size, and easy formation.

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Parks, Daniel, Karim Niang, Yuri Janssen, and Jack W. Simonson. "Synthesis and Crystal Structure of Zr3V3GeSn4." Crystals 13, no. 5 (April 29, 2023): 744. http://dx.doi.org/10.3390/cryst13050744.

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Quantum fluctuations inherent in electronic systems positioned close to magnetic instabilities can lead to novel collective phenomena. One such material, β-Ti6Sn5, sits close to ferromagnetic (FM) instability and can be pushed to an itinerant FM-ordered state with only minute magnetic or non-magnetic doping. The binary nature of this compound, however, limits the tuning variables that can be applied to study any emergent physics, which are likely to be sensitive to the introduction of chemical disorder.Accordingly, we grew high-quality single crystals of a new quaternary compound Zr3V3GeSn4 from a Sn-rich self flux, and determined the structure with single-crystal X-ray diffraction. Zr3V3GeSn4 forms in an ordered derivative of the hexagonal β-Ti6Sn5 structure with Zr and V atomic positions that show no indication of site interchange. Ge likewise occupies a single unique atomic position. The V site, which would be the one most likely to give rise to any magnetic character, is located at the center of a distorted octahedron of Sn, with such octahedra arranged in face-sharing chains along the crystallographic c axis, while the chains themselves are organized in a kagome geometry. Zr3V3GeSn4 represents the second known quaternary phase within this system, suggesting that other compounds with this structure type await discovery.

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Yang, Bo, Xiaoyong Gao, and Cheng Li. "A Novel Micromachined Z-axis Torsional Accelerometer Based on the Tunneling Magnetoresistive Effect." Micromachines 11, no. 4 (April 17, 2020): 422. http://dx.doi.org/10.3390/mi11040422.

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A novel micromachined z-axis torsional accelerometer based on the tunneling magnetoresistive effect is presented in this paper. The plane main structure bonded with permanent magnetic film is driven to twist under the action of inertial acceleration, which results in the opposite variation of the magnetic field intensity. The variation of the magnetic field is measured by two differential tunneling magnetoresistive sensors arranged on the top substrate respectively. Electrostatic feedback electrodes plated on the bottom substrate are used to revert the plane main structure to an equilibrium state and realize the closed-loop detection of acceleration. A modal simulation of the micromachined z-axis tunneling magnetoresistive accelerometer was implemented to verify the theoretical formula and the structural optimization. Simultaneously, the characteristics of the magnetic field were analyzed to optimize the layout of the tunneling magnetoresistance accelerometer by finite element simulation. The plane main structure, fabricated with the process of standard deep dry silicon on glass (DDSOG), had dimensions of 8000 μm (length) × 8000 μm (width) × 120μm (height). A prototype of the micromachined z-axis tunneling magnetoresistive accelerometer was produced by micro-assembly of the plane main structure with the tunneling magnetoresistive sensors. The experiment results demonstrate that the prototype has a maximal sensitivity of 1.7 mV/g and an acceleration resolution of 128 μg/Hz0.5 along the z-axis sensitive direction.

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Дисертації з теми "Electronic Structure - Novel Magnetic Systems"

Nejadsattari, Farshad. "Theoretical and Experimental Studies of Electronic Structure, Magnetic, and Hyperfine Interaction Properties of Novel Compounds." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34572.

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This thesis consists of the results of theoretical and experimental studies on the electronic structure, magnetic properties and hyperfine-interaction parameters of five compounds. The theoretical studies are based on ab-initio calculations, and the experimental studies are based on Mössbauer spectroscopy, magnetic measurements, and X-ray powder diffraction measurements. The calculated hyperfine-interaction parameters are shown to be in good agreement with the corresponding experimental parameters for all studied compounds. Al13Fe4 crystallizes in the monoclinic space group 𝐶2/𝑚, in which Fe atoms are located at five inequivalent crystallographic sites. It is shown that the zero-field Mössbauer spectra can be decomposed into three quadrupole doublets. It is found that the shape of the Mössbauer spectrum measured in an external magnetic field can be accounted for with five component subspectra generated using the calculated EFG parameters at five inequivalent Fe sites. A pseudogap is observed in the density of states (DOS) in the vicinity of the Fermi level. The recently discovered layered iron oxyselenide Na2Fe2Se2O is confirmed to be a Mott insulator. It is demonstrated that Na2Fe2Se2O orders antiferromagnetically. The Debye temperature of Na2Fe2Se2O is found to be 274(3) K. The Fe2NiGa compound crystallizes in the cubic space group 𝐹4 ̅3𝑚 and is predicted to be half-metallic with covalent chemical bonding. It orders ferromagnetically. The saturation magnetization per formula unit and the estimated Fe magnetic moments at the A and B sites are given. It is observed that the magnetic properties of Fe2NiGa are very strongly dependent on their heat treatment. The presence of a mixture of strong covalent and weak ionic chemical bonding and of metallic characteristics for the (Li0.8Fe0.2)OHFeSe superconductor is shown. The Mössbauer spectra consist of two quadrupole-doublet patterns. It is demonstrated that there is no magnetic ordering of the 2𝑎-site Fe magnetic moments down to 2.0 K. The final compound is the Al76Ni9Fe15 approximant. The existence of a pseudogap in the calculated electronic density of states slightly above the Fermi level suggests electronic stabilization according to the Hume-Rothery-type mechanism. High metallicity is predicted. Both the Mössbauer spectra and magnetic susceptibility data indicate that Al76Ni9Fe15 is a paramagnet down to 2.0 K.

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Prudkovskiy, Vladimir. "Electronic properties of quasi-one-dimensional systems (C60@SWCNTs and InAs nanowires) studied by electronic transport under high magnetic field." Thesis, Toulouse, INSA, 2013. http://www.theses.fr/2013ISAT0013/document.

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Cette thèse présente des mesures de transport électronique dans des systèmes quasi-unidimensionnels (quasi-1D) sous champ magnétique intense. Deux systèmes différents présentant un confinement électrique quasi-1D ont été considérés: les peapods de carbone (C60@SWCNTs) et les nanofils d'InAs. L’objectif de ces travaux consiste à sonder les propriétés électroniques spécifiques de ces systèmes quasi-1D par les mesures de magnétotransport sur les nano-objets uniques. Dans les deux cas, les expériences sous champs magnétiques intenses ont été accompagnée par des caractérisations structurales et des mesures de conductance à champ magnétique nul.L'encapsulation de diverses molécules à l'intérieur de nanotubes de carbone (CNTs), comme par exemple les fullerènes C60, constitue une des voies prometteuses vers l'accordabilité de la conductance des CNTs. Parmi la grande variété des nanotubes de carbone remplis, les peapods représentent une structure hybride pionnière découvert en 1998. Depuis lors, leur structure électronique a fait l’objet d’études théoriques controversées avec un nombre limité de réalisations expérimentales. Dans cette thèse, les propriétés électroniques des peapods individuels ont été étudiés en combinant les mesures de spectroscopie micro-Raman et de magnétotransport sur les mêmes échantillons. Nous avons constaté que les C60 encapsulés modifient fortement la structure de bande électronique des nanotubes semi-conducteurs au voisinage du point de neutralité de charge. Cette modification comprend un déplacement rigide de la structure électronique et un remplissage partiel de la bande interdite. Nous avons aussi montré que l’excitation UV sélective des fullerènes conduit à une forte modification du couplage électronique entre les C60 et le CNT induite par la coalescence partielle des C60 et de leur distribution à l'intérieur du tube. Les résultats expérimentaux sont supportés par des simulations numériques de la densité d'états et de la conductance des nanotubes de carbone avec des fullerènes fusionnés à l'intérieur (K. Katin, M. Maslov).Les nanofils semiconducteurs (sc-NWs) font l'objet de recherches actives depuis ces dix dernières années. Ils représentent des systèmes modèles pour l’étude des propriété électronique objet quasi-1D. Ils représentent en outre des possibilités de modulation de la structure de bande aussi que de contrôle de la densité de porteurs. Dans ce domaine de recherche, les nanofils semi-conducteurs à base de composes III-V tel que InAs, ont une place particulière en raison de la faible masse effective des porteurs de charge. Nous avons étudié la conductance de nanofils individuels dans une large gamme de champs magnétiques (jusqu'à 60T). Les mesures en champ nul et en champ faible ont démontré un transport faiblement diffusif dans ces nanofils. Les mesures de transport sous champ magnétique intense ont révélé une forte chute de la conductance au dessus d'un champ critique qui s'élève clairement avec l'énergie de Fermi. Cet effet est interprété par la perte de canaux de conduction une fois que toutes les sous-bandes magnéto-électriques, décalés vers les hautes énergies par le champ magnétique, ont traversé l'énergie de Fermi. Les calculs de structure de bande préliminaires (Y-M. Niquet), en prenant en compte les confinements latéraux et magnétiques, sont en bon accord qualitatif avec les résultats observés dans le régime de champ magnétique intense. Ce résultat est la première observation des effets de structure de bande dans les expériences de magnéto-transport sur les sc-NWs
The scope of this thesis is related to the electronic properties of quasi 1D systems probed by high field magnetotransport. Two different systems exhibiting quasi-1D confinement have been considered: carbon C60 peapods (C60@SWCNTs) and InAs semiconductor nanowires. The magnetotransport measurements on single nano-objets have been used to investigate the specific electronic structure of these 1D systems. In both cases, the high magnetic fields experiments have been supported by structural characterisation and conductance measurements at zero field.The encapsulation of various molecules inside carbon nanotubes (CNTs), as for instance C60 fullerenes encapsulated in SWCNT, constitutes promising routes towards the tunability of the CNT conductance. Among the wide variety of filled CNTs, peapods represent a pioneer hybrid structure discovered in 1998. Since that time, their electronic structure has been subjected to intense and controversial theoretical studies together with a limited number of experimental realizations. In this thesis the electronic properties of individual fullerene peapods have been investigated by combining micro-Raman spectroscopy and magnetotransport measurements on the same devices. We bring evidence that the encapsulated C60 strongly modify the electronic band structure of semiconducting nanotubes in the vicinity of the charge neutrality point, including a rigid shift and a partial filling of the energy gap. In addition by playing with a selective UV excitation of the fullerene, we demonstrate that the electronic coupling between the C60 and the CNT is strongly modified by the partial coalescence of the C60 and their distribution inside the tube. The experimental results are supported by numerical simulations of the Density of States and the conductance of CNTs with coalesced fullerenes inside (K. Katin, M. Maslov).Semiconductor nanowires (sc-NWs) are being the subject of intense researches started a decade ago. They represent model systems for the exploration of the electronic properties inerrant to the quasi1-D confinement. Moreover they offer the possibility to play with band structure tailoring and carrier doping. In this direction III-V sc-NWs such as InAs NWs have played a particular role due to the small electron effective mass. We have studied the high magnetic field conductance of single nanowires. Prior to the high field measurements, the zero and low field investigations have demonstrated a weakly diffusive regime of the carrier transport in these wires. The high field investigations have revealed a drastic conductance drop above a critical field, which clearly rises with the Fermi energy. This effect is interpreted by the loss of conducting channels once all the magneto-electric subbands, shifted toward the high energy range by the magnetic field, have crossed the Fermi energy. Preliminary band structure calculations (Y-M. Niquet), taking into account the lateral and magnetic confinements, are in fairly good qualitative agreement with the observed result in the high field regime. This result is the first observation of band structure effects in magneto-transport experiments on sc-NWs

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Varykhalov, Andrei. "Quantum-size effects in the electronic structure of novel self-organized systems with reduced dimensionality." Phd thesis, Universität Potsdam, 2005. http://opus.kobv.de/ubp/volltexte/2005/578/.

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The Thesis is focused on the properties of self-organized nanostructures. Atomic and electronic properties of different systems have been investigated using methods of electron diffraction, scanning tunneling microscopy and photoelectron spectroscopy. Implementation of the STM technique (including design, construction, and tuning of the UHV experimental set-up) has been done in the framework of present work. This time-consuming work is reported to greater detail in the experimental part of this Thesis.

The scientific part starts from the study of quantum-size effects in the electronic structure of a two-dimensional Ag film on the supporting substrate Ni(111). Distinct quantum well states in the sp-band of Ag were observed in photoelectron spectra. Analysis of thickness- and angle-dependent photoemission supplies novel information on the properties of the interface. For the first time the Ni(111) relative band gap was indirectly probed in the ground-state through the electronic structure of quantum well states in the adlayer. This is particularly important for Ni where valence electrons are strongly correlated. Comparison of the experiment with calculations performed in the formalism of the extended phase accumulation model gives the substrate gap which is fully consistent with the one obtained by ab-initio LDA calculations. It is, however, in controversy to the band structure of Ni measured directly by photoemission. These results lend credit to the simplest view of photoemission from Ni, assigning early observed contradictions between theory and experiments to electron correlation effects in the final state of photoemission.

Further, nanosystems of lower dimensionality have been studied. Stepped surfaces W(331) and W(551) were used as one-dimensional model systems and as templates for self-organization of Au nanoclusters. Photon energy dependent photoemission revealed a surface resonance which was never observed before on W(110) which is the base plane of the terrace microsurfaces. The dispersion E(k) of this state measured on stepped W(331) and W(551) with angle-resolved photoelectron spectroscopy is modified by a strong umklapp effect. It appears as two parabolas shifted symmetrically relative to the microsurface normal by half of the Brillouin zone of the step superlattice. The reported results are very important for understanding of the electronic properties of low-dimensional nanostructures.

It was also established that W(331) and W(551) can serve as templates for self-organization of metallic nanostructures. A combined study of electronic and atomic properties of sub-monolayer amounts of gold deposited on these templates have shown that if the substrate is slightly pre-oxidized and the temperature is elevated, then Au can alloy with the first monolayer of W. As a result, a nanostructure of uniform clusters of a surface alloy is produced all over the steps. Such clusters feature a novel sp-band in the vicinity of the Fermi level, which appears split into constant energy levels due to effects of lateral quantization.

The last and main part of this work is devoted to large-scale reconstructions on surfaces and nanostructures self-assembled on top. The two-dimensional surface carbide W(110)/C-R(15x3) has been extensively investigated. Photoemission studies of quantum size effects in the electronic structure of this reconstruction, combined with an investigation of its surface geometry, lead to an advanced structural model of the carbide overlayer.

It was discovered that W(110)/C-R(15x3) can control self-organization of adlayers into nanostructures with extremely different electronic and structural properties. Thus, it was established that at elevated temperature the R(15x3) superstructure controls the self-assembly of sub-monolayer amounts of Au into nm-wide nanostripes. Based on the results of core level photoemission, the R(15x3)-induced surface alloying which takes place between Au and W can be claimed as driving force of self-organization. The observed stripes exhibit a characteristic one-dimensional electronic structure with laterally quantized d-bands. Obviously, these are very important for applications, since dimensions of electronic devices have already stepped into the nm-range, where quantum-size phenomena must undoubtedly be considered.

Moreover, formation of perfectly uniform molecular clusters of C₆₀ was demonstrated and described in terms of the van der Waals formalism. It is the first experimental observation of two-dimensional fullerene nanoclusters with "magic numbers". Calculations of the cluster potentials using the static approach have revealed characteristic minima in the interaction energy. They are achieved for 4 and 7 molecules per cluster. The obtained "magic numbers" and the corresponding cluster structures are fully consistent with the results of the STM measurements.
Die aktuelle Doktorarbeit ist auf die Eigenschaften von selbst-organisierten Nanostrukturen fokussiert. Die strukturellen und elektronischen Eigenschaften von verschiedenen Systemen wurden mit den Methoden Elektronenbeugung, Rastertunnelmikroskopie und Photoelektronenspektroskopie untersucht. Insbesondere wurde die fuer die Rastertunnelmikroskopie in situ praeparierter Proben eingesetzte Apparatur im Rahmen dieser Arbeit konstruiert und aufgebaut. Einzelheiten hierzu sind im experimentellen Kapitel zu finden.

Der wissenschftliche Teil beginnt mit Untersuchungen von Quantentrogeffekten in der elektronischen Struktur einer Ag-Schicht auf Ni(111)-Substrat. Charakteristische Quantentrogzustaende im Ag-sp-Band wurden in Photoelektronenspektren beobachtet. Die Analyse von schichtdicken- und winkelabhaengiger Photoemission hat neue und wesentliche Informationen ueber die Eigenschaften des Ag/Ni-Systems geliefert. Insbesondere konnte zum ersten Mal eine relative Bandluecke im Ni-Substrat durch das Verhalten der Quantentrogzustaende indirekt vermessen werden. Das ist fuer Ni besonders wichtig, weil es sich bei Ni um ein stark korreliertes Elektronensystem handelt. Die Ergebnisse wurden mit Rechnungen auf der Basis des erweiterten Phasenmodelles verglichen. Der Vergleich ergibt eine Bandluecke, die sehr gut mit ab-initio-Rechnungen auf Basis der lokalen Elektronendichte-Naehrung uebereinstimmen. Dennoch widersprechen die Daten der Ni-Bandstruktur, die direkt mit Photoemission gemessen wird. Diese Kontroverse zeigt deutlich, dass der Unterschied zwischen Theorie und Experiment Korrelationeffekten im Endzustand der Photoemission zugeordnet werden kann.

Des weiteren wurden Nanosysteme von noch niedrigerer Dimensionalitaet untersucht. Gestufte Oberflaechen W(331) und W(551) wurden als eindimensionale Modellsysteme fuer die Selbstorganisation von Au-Nanoclustern benutzt. Photonenenergieabhaengige Photoemission hat eine neue Oberflaechen-resonanz aufgedeckt, die auf der Basisebene der Terrassen dieser Systeme auftritt. Die Dispersion E(k) von diesem Zustand, die mit winkelaufgeloester Photoemission vermessen wurde, zeigt deutlich die Einwirkung von Umklapp-Effekten. Diese zeigen sich als zwei Parabeln, die relativ zu der Terrassennormale symmetrisch um die Haelfte der Oberflaechen-Brillouinzone verschoben sind. Die erzielten Ergebnisse sind sehr wichtig fuer das Verstaendnis der elektronischen Eigenschaften von eindimensionalen Nanostrukturen.

Ausserdem wurde gezeigt, dass W(331) und W(551) als Vorlage fuer selbstorganisierte metallische Nanostrukturen dienen koennen. Eine kombinierte Untersuchung von strukturellen und elektronischen Eigenschaften von unter-monolagen Mengen von Au auf diesen Substraten wurde durchgefuehrt. Es hat sich gezeigt, dass Au mit dem Substrat an der Oberflaeche legieren kann, wenn die Oberflaeche ein wenig oxidiert und die Temperatur erhoert ist. Als Folge formiert sich auf den Stufen eine Nanostruktur von gleichen (aber nicht regelmaessig verteilten) Nanoclustern aus dieser Au-W Legierung. Diese Oberflaechenlegierung bildet ein neuartiges sp-Band in der Naehe der Fermi-Kante. Zudem spaltet dieser neue elektronische Zustand in konstante Energieniveaus auf. Das beobachtete Phaenomen wird als laterale Quantisierung interpretiert.

Das letzte Kapitel dieser Doktorarbeit bildet auch den Hauptteil. Es handelt von Selbstorganisierungsphaenomenen auf einer Oberflaechenrekonstruktion und den Eigenschaften von so hergestellten Nanostrukturen. Das zweidimensionale Oberflaechen-Karbid W(110)/C-R(15x3) wurde intensiv untersucht. Beobachtete Quantentrogeffekte in der Photoemission in Kombination mit den Ergebnissen der Rastertunnelmikroskopuntersuchungen fuehren zu einem verbesserten Strukturmodell fuer das Oberflaechenkarbid.

Es wurde auch gezeigt, dass W(110)/C-R(15x3) die Selbstorganisierung von Nanostrukturen mit sehr verschiedenen elektronischen und strukturellen Eigenschaften steuern kann. Es wurde gefunden, dass bei erhoehter Temperatur die R(15x3)-Ueberstruktur die Bildung von Nanostreifen aus unter-monolagiger Au Bedeckung, von denen jede 1 nm breit ist, kontrolliert. Die hergestellten Nanostreifen besitzen eine charakteristische eindimensionale elektronische Struktur mit lateral quantisierten d-Baendern. Basierend auf der Photoemission von Rumpfniveaus wird eine Kohlenstoff-induzierte Oberflaechenlegierung zwischen Au und W als Grund fuer die beobachtete Organisierung vorgeschlagen. Solche Phaenomene sind sehr wichtig fuer Anwendungen, seit die Mikroelektronik in den nm-Massstab eingetreten ist, in welchem mit Quantentrogeffekten zu rechnen ist.

Zusaetzlich wurde die Bildung von perfekt uniformen molekularen Nanoclustern von C₆₀ auf W(110)/C-R(15x3) demonstriert. Dieses Phaenomen kann im van-der-Waals Formalismus beschrieben werden. Die berichteten Ergebnisse sind eine erstmalige experimentelle Beobachtung von zweidimensionalen Fulleren-Nanoclustern mit "magischen Zahlen". Berechnungen der Clusterpotentiale in der statischen Naeherung im Girifalco-Modell zeigen Minima der Wechselwirkungsenergie fuer Cluster aus 4 und 7 C₆₀-Molekuelen. Diese "magischen Zahlen" sowie die entsprechenden Clusterkonfigurationen sind vollkommen konsistent mit den Ergebnissen des STM-Experiments.

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Palina, Natalie. "Novel magnetic nanoparticles size and surfactant effects on geometric and electronic structure, probed using X-ray absorption spectroscopy /." Bonn : Physikalisches Inst, 2005. http://deposit.d-nb.de/cgi-bin/dokserv?idn=977296059.

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Negodaev, Igor. "The calculation of the thermal dependency of the magnetic susceptibility in extended systems with ab initio electronic structure parameters." Doctoral thesis, Universitat Rovira i Virgili, 2011. http://hdl.handle.net/10803/31934.

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La tesi estudia l'acoblament magnètic en sistemes de diferent dimensionalitat amb mètodes multireferencials. L’objectiu principal del treball és calcular propietats macroscòpiques, com la dependència de la susceptibilitat magnètica amb la temperatura, a partir de la constant d'intercanvi magnètic calculada, J. Aquest paràmetre microscòpic quantifica la interacció magnètica entre dos centres i es pot extreure per ajust de la corba de susceptibilitat experimental en sistemes finits però això no és possible en sistemes magnètics infinits com cadenes o capes 2D. L’estratègia del treball és calcular J en petits clusters i simular els sistemes estesos utilitzant aquesta J en l’Hamiltonià de Heisenberg en models de 8 a 16 centres. Amb l’espectre obtingut es construeixen les corbes de dependència tèrmica de la susceptibilitat magnètica que, comparades amb les experimentals, donen la possibilitat de quantificar les interaccions magnètiques dels materials estudiats a nivell microscòpic. S'han estudiat diferents tipus de sistemes estesos com cadenes i xarxes hexagonals, on els centres magnètics són ions de metalls de transició.
The thesis studies the magnetic coupling in systems of different dimensionality, by using multireference methods. The aim of the work is to determine macroscopic properties such as the thermal dependency of magnetic susceptibility, from the calculated magnetic exchange constant J. This microscopic parameter quantifies the magnetic interaction between two magnetic sites and can be extracted from the experimental susceptibility curve in finite systems. However this extraction is not possible in extended magnetic systems such as chains or 2D-layers. The strategy followed consists in calculating J in small clusters and in simulating the extended systems by introducing the calculated J in the Heisenberg Hamiltonian of 8 to 16 site models. From the spectrum, the thermal dependency of the magnetic susceptibility is the calculated. When compared to the experimental one, this curve gives a quantification of the magnetic interactions of the studied materials at the microscopic level. We have studied different types of extended systems such as chains and hexagonal lattices, where the magnetic sites are transition metal ions.

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Palina, Natalie [Verfasser]. "Novel magnetic nanoparticles : size and surfactant effects on geometric and electronic structure, probed using X-ray absorption spectroscopy / Universität Bonn, Physikalisches Institut. Von Natalie Palina." Bonn : Physikalisches Inst, 2005. http://d-nb.info/977296059/34.

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Greif, Anja Helene [Verfasser], Martin [Akademischer Betreuer] Kaupp, Martin [Gutachter] Kaupp, and Stephan P. A. [Gutachter] Sauer. "Relativistic effects on electronic structure and nuclear magnetic resonance shifts in heavy metal systems / Anja Helene Greif ; Gutachter: Martin Kaupp, Stephan P. A. Sauer ; Betreuer: Martin Kaupp." Berlin : Technische Universität Berlin, 2017. http://d-nb.info/1156013089/34.

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Nogueira, Renata Nascimento. "Propriedades Magnéticas Locais de Grãos de Co em Cu e Ag." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/43/43133/tde-11092012-143911/.

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A descoberta da magnetoresistência (GMR) em materiais granulares gerou um grande interesse no estudo destes materiais, havendo um empenho particular no estudo de grãos de CO em CU e AG. Como as propriedades de transporte estão ligadas intimamente às estruturais, o entendimento da GMR nestes materiais requer uma descrição acurada destas características. Neste trabalho, procurando determinar algumas características magnéticas locais, usamos o método RS-LMTO-ASA para realizar um estudo sistemático dos momentos magnéticos locais e campos hiperfinos com respeito ao tamanho de grãos de CI com até 135 átomos em matrizes de CU e AG fcc. Além disso, estudamos FE e CO nas configurações espaciais seguintes em hospedeiro AG: impurezas isoladas, dímeros FE-FE e FE-CO e precipitados com 13, 19 e 43 átomos. Calculamos o FE enquanto impureza central nos grãos de CO e, para os clusters com 13 e 19 átomos, também consideramos a impureza em posições de interface. Encontramos para os grãos em AG momentos magnéticos bastante estáveis e, para o CU, obtivemos uma ligeira dependência do momento magnético médio com o tamanho do grão. Nossos resultados mostram que há uma diferença significativa no comportamento de grãos e clusters livres. Para os campos hiperfinos, mostramos que este segue comportamentos semelhantes em todos os casos, tendo uma dependência sistemática com relação ao sítio
The discovery of giant magnetoresistance (GMR) in granular materiais generated a great interest in the study of these systems. Special attention has been devoted to Co grains inside Cu and Ag medium. As the transport properties are closely related to structural characteristics, an accurate description is required in order to understand the GMR behavior in these materiais. Here we use the Real Space-LMTO-ASA method to perform a systematic study of the site and grain size dependence of local magnetic moments and hyperfine fields at Co grains ( up to 135 atoms) in fcc Ag and Cu hosts. We have also studied Fe and Co atoms in different spatial configurations in Ag hosts: isolated impurities, Fe-Fe and Fe-Co dimmers and precipitates containing 13, 19 and 43 atoms. Special attention is given to the differences between central and interface positions of Fe atoms in the two smallest Co clusters. We found a very stable value for the local moment at Co atoms in Ag hosts whereas the average local moments for Co grains in Cu tend to be slight ly larger for larger grains. we show that free and embedded Co clusters have very different magnetic behavior. The hyperfine fields present similar values in both matrices and exhibit a systematic site dependence.

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Varma, Rahul Mahavir. "Electronic, Magnetic and Local structure of Some Selected Strongly Correlated Systems." Thesis, 2022. https://etd.iisc.ac.in/handle/2005/6015.

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According to independent electron band structure theories, transition metal oxides (TMOs) with partially filled 3d valence band are predicted to be metallic in nature. Though in reality, most of them are insulators. Mott and later Hubbard introduced electron-electron interactions in order to explain such insulating behaviors. These systems are often known as Mott-Hubbard insulators (or Mott insulators). Such systems have attracted a great deal of attention in the last several decades, not only due to the intriguing physics observed in these materials with variations in pressure, temperature, doping, etc., but also due to their diverse application potentials. The discovery of high-temperature superconductivity (high-TC) in the copper-based TMOs regenerated the interest in these systems characterized by strong electron-electron interactions; such systems are generally called strongly correlated systems (SCS) to include materials that are not necessarily insulating, but whose properties are believed to be controlled by strong electron-electron interactions. These SCS, particularly those based on the 3d TMOs, are of great importance and cover various phenomena such as metal-insulator transitions (MIT), high-TC superconductivity, and colossal magnetoresistance. All such exciting properties, shown by 3d TMOs, are fundamentally important due to the presence of a partially filled 3d valence band (VB) and to understand such properties, one needs to investigate the electronic and crystal structures of these materials. In this thesis, we have investigated the electronic, magnetic, and local geometric structures of some selected strongly correlated systems with interesting properties like MIT, and strong magnetoelectric coupling with the help of different high energy spectroscopic techniques along with dielectric and magnetic measurements. The samples reported in this thesis were prepared by various synthetic routes, such as solid-state reaction, sol-gel method, and d.c arc melting. These samples were characterized by x-ray diffraction, magnetic susceptibility, optical absorption, dielectric constant and energy dispersive analysis of x-rays. Various spectroscopic techniques like Hard X-ray Photoemission Spectroscopy (HAXPES) and Extended X-ray Absorption Fine Structure (EXAFS) were used to probe the electronic and local structures of the samples of Nickel Oxide (NiO), La1-xCaxVO3, Ga-doped YMnO3 and La-doped SrTiO3

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Pal, Banabir. "Electronic and Magnetic Structures of Some Selected Strongly Correlated Systems." Thesis, 2016. http://etd.iisc.ac.in/handle/2005/2970.

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Transition metal oxides and chalcogenides are an ideal platform for demonstrating and investigating many interesting electronic phases of matter. These phases emerge as a result of collective many body interactions among the electrons. The omnipresent electron, depending on its interaction with other electrons and with the underlying lattice, can generate diverse phases of matter with exotic physical properties. The ultimate objective of Materials Science is to provide a complete microscopic understanding of these myriad electronic phases of matter. A proper understanding of the collective quant-tum behaviour of electrons in different system can also help in designing and tuning new electronic phases of matter that may have strong impact in the field of microelectronics, well beyond that predicted by Moore s law. Strong electron correlation effects produce a wide spectrum of ground state prop-retires like superconductivity, Metal Insulator Transition (MIT), charge-orbital ordering and many more. Similarly, different spin interactions among electrons, essentially due to various kinds of exchange coupling, give rise to varying magnetic ground state prop-retires like ferromagnetism, anti-ferromagnetism, spin glass, among others. The main objective of this thesis is to understand and rationalize diverse electronic and magnetic phases of matter in some selected strongly correlated systems. In chapter 1 we have provided an overview of various electronic and magnetic phases of matter which are relevant and necessary for understanding the chapters that follow. The first part of this chapter describes the fundamental concepts of the so called Metal Insulator Transition (MIT). A small section is dedicated to the subtle interactions among electrons and lattice that actually drive a system from a highly conducting metallic state to a strongly resistive insulating state. The second part of this chapter offers a compilation of different magnetic ground states which are discussed in detail in the last two chapters. In Chapter 2, we have explained various methodologies and experimental tech-antiques that have been used in the work reported in this thesis. In Chapter 3, we have provided a detailed understanding of the MIT in different polymorphic forms of Vanadium dioxide (VO2). Although VO2 exhibits a number of polymorphic forms, only the rutile/monoclinic VO2 phase has been studied extensively compared to other polymorphic forms. This phase shows a well-established MIT across ∼340 K, which has been extensively investigated in order to understand the relative importance of many body electron correlation effects arising primarily from on-site Coulomb interactions within the Vanadium 3d manifold, and single electron effects flounced by the dimerization of Vanadium atoms. Unlike the rutile phase of VO2, little is known about the MIT appearing across 212 K in the metastable B-phase of VO2. This phase shows dimerization of only half of the Vanadium atoms in the insulating state, in contrast to rutile/monoclinic VO2, which show complete dimerization. There is a long standing debate about the origin of the MIT in the rutile/monoclinic phase, that contrasts the role of the many-body Hubbard U term, with single particle effects of the dimerization. In light of this debate, the MIT in the B-phase offers a unique opportunity to understand and address the competition between many body and single particle effects, that has been unresolved over several decades. In this chapter we have investigated different polymorphs of VO2 to understand the underlying electronic structure and the nature of the MIT in these polymorphic forms. The MIT in VO2 B phase is very broad in nature. X-ray photoemission and optical conductivity data indicate that in case of VO2 B phase both correlation effects and dimerization is necessary to drive the MIT. We have also established that the correlation effects are more prominent for VO2 B phase compared to rutile/monoclinic phase. In Chapter 4, we have discussed the electronic structure of LaTiO3 (LTO)-SrTiO3 (STO) system. At the interface between polar LTO and non-polar (STO) oxides, an unique two dimensional electron gas (2DEG) like state appears, that exhibits a phenomenal range of unexpected transport, magnetic, and electronic properties. Thus, this interface stands as a prospective candidate for not only fundamental scientific investigation, but also application in technological and ultimately commercial frontiers. In this chapter, using variable energy Hard X-ray photoemission spectroscopy (HAXPES), we have experimentally investigated the layer resolved evolution of electronic structure across the interface in LTO-STO system. HAXPES results suggest that the interface is more coherent in nature and the coherent to incoherent feature ratio changes significantly as we probe deeper into the layer In chapter 5, we have investigated the electronic structure of the chemically exfoliated trigonal phase of MoS2. This elusive trigonal phase exists only as small patches on chemically exfoliated MoS2, and is believed to control functioning of MoS2 based devices. Its electronic structure is little understood, with total absence of any spec-troscopic data, and contradictory claims from theoretical investigations. We have ad-dressed this issue experimentally by studying the electronic structure of few layered chemically exfoliated MoS2 systems using spatially resolved X-ray photoemission spec-otoscopy and micro Raman spectroscopy in conjunction with electronic structure calculations. We have established that the ground state of this unique trigonal phase is actually a small gap (∼90 meV) semiconductor. This is in contrast with most of the claims in existing literature. In chapter 6, we have re-examined and revaluated the electronic structure of the late 3d transition metal monoxides (NiO, FeO, and CoO) using a combination of HAX-PES and state-of-the-art theoretical calculations. We have observed a strong evolution in the valence band spectra as a function of excitation energy. Theoretical results show that a combined GW+LDA+DMFT scheme is essential for explaining the observed experimental findings. Additionally, variable temperature HAXPES measurement In chapter 8, we have differentiated the surface and the bulk electronic structure in Sr2FeMoO6 and also have provided a new route to increase the Curie temperature of this material. Sr2FeMoO6 is well known for its high Curie temperature (Tc ∼410 K), half-metallic ferromagnetism, and a spectacularly large tunnelling magnetoresistance. The surface electronic structure of Sr2FeMoO6 is believed to be different from the bulk; leading to a Spin-Valve type Magnetoresistance. We have carried out variable energy HAXPES on Sr2FeMoO6 to probe electronic structure as a function of surface depth. Our experimental results indicate that surface is more Mo6+ rich. We have also demonstrated what we believe is the first direct experimental evidence of hard ferro-magnetism in the surface layer using X Ray Magnetic Circular Dichroism (XMCD) with dual detection mode. In the second part of this chapter we have designed a new route to increase the Curie temperature and have been successfully able to achieve a Curie temperature as high as 515 K.

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Книги з теми "Electronic Structure - Novel Magnetic Systems"

Rader, Oliver. Novel effects observed in ultrathin magnetic films: Magnetic quantum-well, interface, and correlation-induced states. Berlin: Wissenschaft & Technik Verlag, 1995.

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Farrow, Robin F. C. Magnetism and structure in systems of reduced dimension. Boston, MA: Springer, 1993.

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Winkler, Roland. Spin-orbit coupling effects in two-dimensional electron and hole systems. Berlin: Springer, 2003.

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Narlikar, A. V., and Y. Y. Fu, eds. Oxford Handbook of Nanoscience and Technology. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533046.001.0001.

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This Handbook consolidates some of the major scientific and technological achievements in different aspects of the field of nanoscience and technology. It consists of theoretical papers, many of which are linked with current and future nanodevices, molecular-based materials and junctions (including Josephson nanocontacts). Self-organization of nanoparticles, atomic chains, and nanostructures at surfaces are further described in detail. Topics include: a unified view of nanoelectronic devices; electronic and transport properties of doped silicon nanowires; quasi-ballistic electron transport in atomic wires; thermal transport of small systems; patterns and pathways in nanoparticle self-organization; nanotribology; and the electronic structure of epitaxial graphene. The volume also explores quantum-theoretical approaches to proteins and nucleic acids; magnetoresistive phenomena in nanoscale magnetic contacts; novel superconducting states in nanoscale superconductors; left-handed metamaterials; correlated electron transport in molecular junctions; spin currents in semiconductor nanostructures; and disorder-induced electron localization in molecular-based materials.

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Novel Electronic Structure Theory : General Innovations and Strongly Correlated Systems: General Innovations and Strongly Correlated Systems. Elsevier Science & Technology Books, 2018.

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Hoggan, Philip E. Novel Electronic Structure Theory: General Innovations and Strongly Correlated Systems. Elsevier Science & Technology Books, 2018.

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Novel Electronic Structure Theory: General Innovations and Strongly Correlated Systems. Elsevier, 2018. http://dx.doi.org/10.1016/s0065-3276(17)x0004-x.

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Spin-orbit Coupling Effects in Two-Dimensional Electron and Hole Systems. Springer, 2003.

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Winkler, Roland. Spin-Orbit Coupling Effects in Two-Dimensional Electron and Hole Systems. Springer, 2003.

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Winkler, Roland. Spin-orbit Coupling Effects in Two-Dimensional Electron and Hole Systems. Springer, 2010.

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Частини книг з теми "Electronic Structure - Novel Magnetic Systems"

Giannozzi, Paolo. "Large-Scale Electronic Structure Calculations in Solids." In Computational Approaches to Novel Condensed Matter Systems, 67–86. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4757-9791-6_4.

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Galli, Giulia. "Structure, Stability and Electronic Properties of Nanodiamonds." In Computer-Based Modeling of Novel Carbon Systems and Their Properties, 37–56. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-1-4020-9718-8_2.

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Donath, Markus. "Spin-Dependent Empty Electronic States at Magnetic Surfaces." In Magnetism and Structure in Systems of Reduced Dimension, 243–55. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4899-1519-1_21.

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Halilov, S. "Low-Lying Magnetic Excitations in Itinerant Systems: SDFT Calculations." In Electronic Structure and Magnetism of Complex Materials, 1–56. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-662-05310-2_1.

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Chakraborty, Tapash, Aram Kh Manaselyan, and Manuk G. Barseghyan. "Electronic, Magnetic and Optical Properties of Quantum Rings in Novel Systems." In Physics of Quantum Rings, 283–326. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-95159-1_11.

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Kurkina, L. I., O. V. Farberovich, V. S. Stepanyuk, A. A. Katsnelson, and A. Szasz. "Calculation of the Electronic Structure and Magnetic Properties of Iron Microclusters." In Physics and Chemistry of Finite Systems: From Clusters to Crystals, 623–28. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-017-2645-0_82.

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Entel, Peter, Raymundo Arróyave, Navdeep Singh, Vladimir V. Sokolovskiy, and Vasiliy D. Buchelnikov. "Calculation of Electronic Structure and Field Induced Magnetic Collapse in Ferroic Materials." In TMS Middle East - Mediterranean Materials Congress on Energy and Infrastructure Systems (MEMA 2015), 403–8. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2015. http://dx.doi.org/10.1002/9781119090427.ch42.

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Entel, Peter, Raymundo Arróyave, Navdeep Singh, Vladimir V. Sokolovskiy, and Vasiliy D. Buchelnikov. "Calculation of Electronic Structure and Field Induced Magnetic Collapse in Ferroic Materials." In Proceedings of the TMS Middle East — Mediterranean Materials Congress on Energy and Infrastructure Systems (MEMA 2015), 405–8. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-48766-3_42.

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Hauser, Andreas W., Carlo Callegari, and Wolfgang E. Ernst. "Level-Structure and Magnetic Properties from One-Electron Atoms to Clusters with Delocalized Electronic Orbitals: Shell Models for Alkali Trimers." In Advances in the Theory of Atomic and Molecular Systems, 201–15. Dordrecht: Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-90-481-2985-0_10.

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Lunghi, Alessandro. "Spin-Phonon Relaxation in Magnetic Molecules: Theory, Predictions and Insights." In Challenges and Advances in Computational Chemistry and Physics, 219–89. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-31038-6_6.

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AbstractMagnetic molecules have played a central role in the development of magnetism and coordination chemistry, and their study keeps leading innovation in cutting-edge scientific fields such as magnetic resonance, magnetism, spintronics, and quantum technologies. Crucially, a long spin lifetime well above cryogenic temperature is a stringent requirement for all these applications. In this chapter, we review the foundations of spin relaxation theory and provide a detailed overview of first-principles strategies applied to the problem of spin-phonon relaxation in magnetic molecules. Firstly, we present a rigorous formalism of spin-phonon relaxation based on open-quantum systems theory. These results are then used to derive classical phenomenological relations based on the Debye model. Finally, we provide a prescription of how to map the relaxation formalism onto existing electronic structure methods to obtain a quantitative picture of spin-phonon relaxation. Examples from the literature, including both transition metals and lanthanides compounds, will be discussed in order to illustrate how Direct, Orbach, and Raman relaxation mechanisms can affect spin dynamics for this class of compounds.

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Тези доповідей конференцій з теми "Electronic Structure - Novel Magnetic Systems"

Zhao, B. "Magnetic Systems with Carbon Nanotubes." In STRUCTURAL AND ELECTRONIC PROPERTIES OF MOLECULAR NANOSTRUCTURES: XVI International Winterschool on Electronic Properties of Novel Materials. AIP, 2002. http://dx.doi.org/10.1063/1.1514188.

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Alizadeh Tir, Milad, Seyyed Mehdi Mirimani, and Fabrizio Marignetti. "A novel structure of passive magnetic bearing with axial magnetization." In 2014 5th Power Electronics, Drive Systems & Technologies Conference (PEDSTC). IEEE, 2014. http://dx.doi.org/10.1109/pedstc.2014.6799392.

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Li, Zhongjie, Xiaomeng Jiang, Yan Peng, Jun Luo, Shaorong Xie, and Huayan Pu. "Design and Experimental Studies of a Heel-Embedded Energy Harvester for Self-Powered Wearable Electronics." In ASME 2021 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/smasis2021-68087.

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Abstract Recent decades have witnessed a booming increase in the number of wearable electronic devices. However, these devices cannot work for a very long time due to the limited lifespan of internal electrochemical batteries. In this article, we present a novel wearable electromagnetic energy harvester (EMEH) embedded into a heel of a shoe to collect the kinetic energy from human motion to tackle the above problem. The harvester is mainly composed of a pedal, four springs, a cantilever, and an electromagnetic energy transduction unit. In this design, we adopt a cantilever and a two-stage displacement amplification mechanism to convert up the frequency of the excitation, magnify the input displacement from the foot, and take advantage of an alternating magnet pole arrangement to get abrupt changes in the magnetic flux density (MFD). An electromagnetic dynamic model was established to simulate the output power of the harvester. Besides, we fabricated a prototype to examine the output performance of the harvester. The results prove that the cantilever can effectively convert low-frequency human running motions into high-frequency oscillations, which crucially contributes to the high performance of the harvester. As a portable energy conversion source, the proposed harvester can be of great significance in promoting the development of wearable self-powered electronic devices.

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Lee, Chia-Yen, Zgen-Hui Chen, and Chih-Yung Wen. "An Electromagnetic Actuator in Lab-on-a-Chip Systems." In ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer. ASMEDC, 2008. http://dx.doi.org/10.1115/mnht2008-52037.

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A novel technique for the fabrication of electromagnetic micro actuators was proposed and a prototype was designed and fabricated in this study. The constituent parts of the designed actuator are comprised of the diaphragm, the micro coils, and the magnet. When an electrical current was applied to the micro coils, the magnetic force between the magnet and the coil is produced, causes the diaphragm to deflect and becomes the source of actuation. The fabrication process of the actuator combines Optical Lithography, Electron Beam Evaporation, and Electroplating. The structure of the actuating device uses PDMS as the vibrating diaphragm and electroplated copper as the coils. The diaphragm deflection can be regulated by varying the electrical current passed through the micro coil and hence the actuating effects can be controlled. The experimental results show that the maximum diaphragm deflection within elastic limits is 150 μm at an electrical current of 0.6 A for a micro coil of 100 μm line width. The micro electromagnetic actuator proposed in this study is easily fabricated and is readily integrated with Lab-on-a-Chip systems due to its planar structure.

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Peng, Yan, Dong Zhang, Jun Luo, Shaorong Xie, Huayan Pu, and Zhongjie Li. "Harnessing Kinetic Energy From Human Motions With a High-Efficiency Wearable Electromagnetic Energy Harvester." In ASME 2020 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/smasis2020-2222.

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Abstract Recent years have witnessed explosive increase in the number of wearable devices in the market and industry. However, hardly have these devices gained the ability to capture energy from hosts and then get self-charged. In this paper, we design and build a novel wearable electromagnetic energy harvester to scavenge the kinetic energy of human ankle during walking or running. The design is composed of mainly three parts: a spring-mass system, rolling ball pair and the electromagnetic transduction mechanism. The harvester adopts an array of alternating south- and north-pole magnets. This arrangement allows the array exhibits a unique phenomenon, i.e. abrupt magnetic flux density changes within the array. Because of this phenomenon, the harvester displays excellent performance such as relatively high voltage and high power output. We then conducted FEM analysis to validate the hypothetical abrupt flux density changes. A prototype was fabricated for experimental studies. We investigated open-circuit voltage output, current output, and power as well as charging performance into energy storage components. The result shows that harvester possesses excellent performance with the maximum output voltage of 8.64V, peak-peak power of 700mW and the highest volume power density of 24.9mW/cm3. The energy harvester, as a renewable portable power source, can be of great significance for powering smart wearable electronic devices and health care monitoring sensors.

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Kumar, G. Vijay, and Anmv Srivalli. "A novel structure of embryonics electronic cell array." In 2015 International Conference on Signal Processing And Communication Engineering Systems (SPACES). IEEE, 2015. http://dx.doi.org/10.1109/spaces.2015.7058222.

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Ishii, K. "Crystal structure and magnetic properties of Eu[sub x]Sr[sub 6−x]C[sub 60]." In The 14th international winterschool on electronic properties of novel materials - molecular nanostructures. AIP, 2000. http://dx.doi.org/10.1063/1.1342461.

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Zeng, Xianrui, Jianwei Mai, Xuesong Gao, Yousu Yao, Yijie Wang, and Dianguo Xu. "A Novel Magnetic Shielding Structure for Inductive Wireless Power Transfer Systems Based on Constraint of Magnetic Flux." In 2021 IEEE 12th Energy Conversion Congress & Exposition - Asia (ECCE-Asia). IEEE, 2021. http://dx.doi.org/10.1109/ecce-asia49820.2021.9479039.

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Wang, Huisheng, and Xiuping Li. "Two novel 60 GHz coplanar waveguide structure filters with electric and magnetic coupling." In 2011 IEEE International Conference on Cloud Computing and Intelligence Systems (CCIS). IEEE, 2011. http://dx.doi.org/10.1109/ccis.2011.6045139.

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Namiki, Takahiro, Hidetsugu Waki, Seiya Shibata, Akari Kawasaki, Yuki Matsumoto, and Katsuhiko Nishimura. "Electronic and Magnetic Properties of Caged-Structure Intermetallic Compounds CeT2Al20 (T = Nb, Mo)." In Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2019). Journal of the Physical Society of Japan, 2020. http://dx.doi.org/10.7566/jpscp.30.011103.

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Звіти організацій з теми "Electronic Structure - Novel Magnetic Systems"

Hadjipanayis, George, and Alexander Gabay. Electronic Structure and Spin Correlations in Novel Magnetic Structures. Office of Scientific and Technical Information (OSTI), June 2021. http://dx.doi.org/10.2172/1797990.

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Balasubramanian, Bala. Electronic Structure and Quantum Spin Correlations in Novel Magnetic Compounds. Office of Scientific and Technical Information (OSTI), June 2022. http://dx.doi.org/10.2172/1901978.

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