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Articles de revues sur le sujet "Light-Induced magnetism"
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Cheng, Oscar Hsu-Cheng, Dong Hee Son et Matthew Sheldon. « Light-induced magnetism in plasmonic gold nanoparticles ». Nature Photonics 14, no 6 (16 mars 2020) : 365–68. http://dx.doi.org/10.1038/s41566-020-0603-3.
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Many, Véronique, Romain Dézert, Etienne Duguet, Alexandre Baron, Vikas Jangid, Virginie Ponsinet, Serge Ravaine, Philippe Richetti, Philippe Barois et Mona Tréguer-Delapierre. « High optical magnetism of dodecahedral plasmonic meta-atoms ». Nanophotonics 8, no 4 (20 décembre 2018) : 549–58. http://dx.doi.org/10.1515/nanoph-2018-0175.
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AbstractThe generation in artificial composites of a magnetic response to light, comparable in magnitude with the natural electric response, may offer an invaluable control parameter for a fine steering of light at the nanoscale. In many experimental realizations, however, the magnetic response of artificial meta-atoms is too weak so that there is a need for new designs with increased magnetic polarizability. Numerical simulations show that geometrical plasmonic nanostructures based on Platonic solids are excellent candidates for the production of strong optical magnetism in visible light. Inspired by these models, we report a bottom-up approach to synthesize plasmonic nanoclusters made of 12 gold patches located at the center of the faces of a dodecahedron. The scattering of the electric and magnetic dipole induced by light is measured across the whole visible range. The ratio of the magnetic to electric response at resonance is found three times higher than its counterpart measured on disordered plasmonic clusters (“plasmonic raspberries”) of the same size. Numerical simulations confirm the experimental measurements of the magnetic response.
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Epstein, Arthur J. « Organic-Based Magnets : Opportunities in Photoinduced Magnetism, Spintronics, Fractal Magnetism, and Beyond ». MRS Bulletin 28, no 7 (juillet 2003) : 492–99. http://dx.doi.org/10.1557/mrs2003.145.
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AbstractThis article is based on a presentation on organic-based magnets given as part of Symposium X—Frontiers of Materials Research on December 4, 2002, at the 2002 Materials Research Society Fall Meeting in Boston. The advent of organic-based magnets opened the opportunity for tuning magnetic properties by molecular design and the discovery of new phenomena that rely on the internal structure of the molecules that make up these magnets. In the past 18 years, numerous classes of organic-based ferromagnets, ferrimagnets, and spin glasses (spins essentially frozen in place without long-range order) have been reported. These materials have magnetic ordering temperatures ranging from <1 K to above room temperature and demonstrate many of the magnetic properties associated with conventional magnets. This article concentrates on new phenomena that are unique to organic-based magnets. Three of these effects—“high-temperature” light-induced magnetism, spin-polarized magnetic organic semiconductors with the potential for spintronics, and the development of fractal magnetic order—are discussed to illustrate the richness of opportunity in organic-based magnets.
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Zeng, Jinwei, Mohammad Kamandi, Mahsa Darvishzadeh-Varcheie, Mohammad Albooyeh, Mehdi Veysi, Caner Guclu, Mina Hanifeh et al. « In pursuit of photo-induced magnetic and chiral microscopy ». EPJ Applied Metamaterials 5 (2018) : 7. http://dx.doi.org/10.1051/epjam/2018002.
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Light-matter interactions enable the perception of specimen properties such as its shape and dimensions by measuring the subtle differences carried by an illuminating beam after interacting with the sample. However, major obstacles arise when the relevant properties of the specimen are weakly coupled to the incident beam, for example when measuring optical magnetism and chirality. To address this challenge we propose the idea of detecting such weakly-coupled properties of matter through the photo-induced force, aiming at developing photo-induced magnetic or chiral force microscopy. Here we review our pursuit consisting of the following steps: (1) Development of a theoretical blueprint of a magnetic nanoprobe to detect a magnetic dipole oscillating at an optical frequency when illuminated by an azimuthally polarized beam via the photo-induced magnetic force; (2) Conducting an experimental study using an azimuthally polarized beam to probe the near fields and axial magnetism of a Si disk magnetic nanoprobe, based on photo-induced force microscopy; (3) Extending the concept of force microscopy to probe chirality at the nanoscale, enabling enantiomeric detection of chiral molecules. Finally, we discuss difficulties and how they could be overcome, as well as our plans for future work.
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Lohmann, Sven‐Hendrik, Tong Cai, Darien J. Morrow, Ou Chen et Xuedan Ma. « Brightening of Dark States in CsPbBr 3 Quantum Dots Caused by Light‐Induced Magnetism ». Small 17, no 37 (8 août 2021) : 2101527. http://dx.doi.org/10.1002/smll.202101527.
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Wang, Yihua. « Broken-symmetry states in topological insulators ». Modern Physics Letters B 29, no 25 (20 septembre 2015) : 1530006. http://dx.doi.org/10.1142/s0217984915300069.
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Breaking the time-reversal symmetry (TRS) on the surface of a three-dimensional topological insulator (TI) transforms its metallic surface into a Chern insulator. The TRS-broken surface states are essential for many exotic emergent particles in condensed matter. In this review, I will show broken TRS surface states of TI induced by magnetism and by light imaged with scanning microscopy and photoemission spectroscopy, respectively. Our capability to manipulate mesoscopic magnetic structures as well as to shape ultrafast light pulses makes broken-symmetry states in TI promising platforms to simulate elusive fundamental particles such as magnetic monopoles and Majorana fermions.
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KUZEMSKY, A. L. « UNCONVENTIONAL AND EXOTIC MAGNETISM IN CARBON-BASED STRUCTURES AND RELATED MATERIALS ». International Journal of Modern Physics B 27, no 11 (25 avril 2013) : 1330007. http://dx.doi.org/10.1142/s0217979213300077.
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The detailed analysis of the problem of possible magnetic behavior of the carbon-based structures was fulfilled to elucidate and resolve (at least partially) some unclear issues. It was the purpose of the present paper to look more critically into some conjectures which have been made and to the peculiar and contradictory experimental results in this rather indistinct and disputable field. First the basic physics of magnetism was briefly addressed. Then a few basic questions were thoroughly analyzed and critically reconsidered to elucidate the possible relevant mechanism (if any) which may be responsible for observed peculiarities of the "magnetic" behavior in these systems. The arguments supporting the existence of the intrinsic magnetism in carbon-based materials, including pure graphene were analyzed critically. It was concluded that recently published works have shown that the results of the previous studies, where the "ferromagnetism" was detected in pure graphene, were incorrect. Rather, graphene is strongly diamagnetic, similar to graphite. Thus the possible traces of a quasi-magnetic behavior which some authors observed in their samples may be attributed rather to induced magnetism due to the impurities, defects, etc. On the basis of the present analysis the conclusion was made that the thorough and detailed experimental studies of these problems only may shed light on the very complicated problem of the magnetism of carbon-based materials. Lastly the peculiarities of the magnetic behavior of some related materials and the trends for future developments were mentioned.
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Lü, Xiao-Long, et Hang Xie. « Topological edge states and transport properties in zigzag stanene nanoribbons with magnetism ». New Journal of Physics 24, no 3 (1 mars 2022) : 033010. http://dx.doi.org/10.1088/1367-2630/ac4009.
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Abstract In this work, we investigate the topological phase transitions and corresponding transport properties in zigzag stanene nanoribbon with different magnetism. The results show that the off-resonant circularly polarized (ORCP) light may induce anisotropic chiral edge state with a magnetic phase transition from antiferromagnetic state to nonmagnetic state. In combination with the ORCP light and electric field, the 100% spin-polarized edge state can be induced with some magnetic orders. The finite-size effect is also an important factor for the magnetic phase transitions, which in turn induces topological phase transitions from the band insulator to topological phases. By constructing the topological-insulator junctions with some topological edge states, we further study the Fabry–Perot resonant, where multiple reflection edge states cause strong current loops. By modulating the ORCP and electric field, the system can also be regarded as a switcher, to control the charge current or spin polarized current. These findings pave a way for designing topological device with magnetic edges in the future nano spintronics.
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Marzal, Vicente, Juan Carlos Torres, Isabel Pérez, José Manuel Sánchez-Pena et Braulio García-Cámara. « Induced Magnetic Anisotropy in Liquid Crystals Doped with Resonant Semiconductor Nanoparticles ». Journal of Nanomaterials 2016 (2016) : 1–9. http://dx.doi.org/10.1155/2016/7659074.
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Currently, there are many efforts to improve the electrooptical properties of liquid crystals by means of doping them with different types of nanoparticles. In addition, liquid crystals may be used as active media to dynamically control other interesting phenomena, such as light scattering resonances. In this sense, mixtures of resonant nanoparticles hosted in a liquid crystal could be a potential metamaterial with interesting properties. In this work, the artificial magnetism induced in a mixture of semiconductor nanoparticles surrounded by a liquid crystal is analyzed. Effective magnetic permeability of mixtures has been obtained using the Maxwell-Garnett effective medium theory. Furthermore, permeability variations with nanoparticles size and their concentration in the liquid crystal, as well as the magnetic anisotropy, have been studied.
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Kitagawa, Jiro, Kohei Sakaguchi, Tomohiro Hara, Fumiaki Hirano, Naoki Shirakawa et Masami Tsubota. « Interstitial Atom Engineering in Magnetic Materials ». Metals 10, no 12 (6 décembre 2020) : 1644. http://dx.doi.org/10.3390/met10121644.
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Interstitial light elements play an important role in magnetic materials by improving the magnetic properties through changes of the unit cell volume or through orbital hybridization between the magnetic and interstitial atoms. In this review focusing on the effects of interstitial atoms in Mn-based compounds, which are not well researched, the studies of interstitial atoms in three kinds of magnetic materials (rare-earth Fe-, Mn-, and rare-earth-based compounds) are surveyed. The prominent features of Mn-based compounds are interstitial-atom-induced changes or additional formation of magnetism—either a change from antiferromagnetism (paramagnetism) to ferromagnetism or an additional formation of ferromagnetism. It is noted that in some cases, ferromagnetic coupling can be abruptly caused by a small number of interstitial atoms, which has been overlooked in previous research on rare-earth Fe-based compounds. We also present candidates of Mn compounds, which enable changes of the magnetic state. The Mn-based compounds are particularly important for the easy fabrication of highly functional magnetic devices, as they allow on-demand control of magnetism without causing a large lattice mismatch, among other advantages.
Thèses sur le sujet "Light-Induced magnetism"
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Scheid, Philippe. « Investigation of light–induced ultrafast magnetization dynamics using ab initio methods ». Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0166.
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Cette thèse commence par une revue de l’état actuel de l’expérimentation et de la théorie liées à la désaimantation ultrarapide induite par de la lumière, ainsi qu'au retournement tout optique dépendant de l'hélicité. Ceci est suivi d’un aperçu de la théorie de la fonctionnelle de la densité, sur laquelle repose la plupart des travaux rapportés par la suite. La première partie des résultats concerne l’étude de l’effet d’une élévation de la température électronique sur les propriétés de la matière aimantée, et plus précisément Ni, Co, Fe et FePt. Nous montrons que le moment magnétique de chaque atome disparaı̂t à la température de Stoner, et que, de manière plus générale ce phénomène impacte l’énergie électronique et la chaleur spécifique, même à basse température électronique. Ensuite, nous montrons que lors d’une augmentation de la température électronique, l’échange interatomique d’Heisenberg, responsable de l’ordre magnétique, diminue. En utilisant l’équation de Landau–Lifshitz–Gilbert atomistique, nous démontrons que cette diminution est suffisante pour induire une forte réduction de l’aimantation moyenne en créant des excitations transversales. La deuxième partie des résultats concerne l’origine de la dépendante en l’hélicité de la dynamique induite par la lumière. Alors que la littérature l’attribue principalement à l’effet Faraday inverse, nous soutenons qu’un autre phénomène, se produisant lors de l’absorption de la lumière, peut rendre compte de la dynamique expérimentale. En effet, lorsque la lumière est absorbée et que les électrons sont excités, le couplage spin–orbite permet la modification de l’état de spin. Il en résulte un changement de la valeur des moments magnétiques atomiques, persistant même après la disparition de la lumière, par opposition à l’effet Faraday inverse. Ensuite, en utilisant la théorie de la fonctionnelle de la densité dépendante du temps, nous calculons la dynamique de l’aimantation induite par de véritables impulsions femtosecondes polarisées circulairement dans le domaine optique et XUV. Dans les deux cas, la dynamique est dépendante de l’hélicité. Cette caractéristique est largement amplifiée dans le régime XUV impliquant les états de semi–coeur 3p. Enfin, nous comparons le rôle relatif de l’effet Faraday inverse et de l’aimantation induite lors de l’absorption de la lumière et montrons que cette dernière joue un rôle prépondérant, surtout après la disparition de la lumière et en régime XUVThis thesis begins with a review of the current experimental and theoretical state of the art related to the light-induced ultrafast demagnetization and the all-optical helicity-dependent switching. This is followed by an overview of density functional theory, upon which relies most of the work reported thereafter. The first set of results concerns the ab initio study of the effect of a rise in the electronic temperature on the magnetized matter properties, and more specifically Fe, Co, Ni and FePt. We show that the magnetic moment carried by each atom disappears at the so–called Stoner temperature, and that this phenomenon impacts the electronic energy and specific heat, even at low electronic temperature. Then, we show that upon an increase in the electronic temperature, the interatomic Heisenberg exchange, which is responsible for the magnetic ordering, decreases. Using the atomistic Langevin Landau–Lifshitz–Gilbert equation, we demonstrate that this decrease is enough to induce a large reduction of the average magnetization by creating transversal excitations. The second set of results regards the origin of the helicity–dependent light–induced dynamics. While the literature attributes it mainly to the inverse Faraday effect, we argue that another and novel phenomenon, which occurs during the absorption of the light, may be more suited to account for the experimental dynamics. Indeed, using the Fermi golden rule and ground state density functional theory calculations in Fe, Co, Ni and FePt, we show that, as the light is absorbed and electrons are excited, concurrently to the increase of the electronic energy, the spin–state is also changed in presence of spin–orbit coupling. This results in a difference in the value of the atomic magnetic moments, persisting even after the light is gone, as opposed to the inverse Faraday effect. Then, using real–time time–dependent density functional theory, we compute the magnetization dynamics induced by real optical and XUV femtosecond circularly polarized pulses. We show that, in both cases the dynamics is helicity–dependent and that this characteristic is largely amplified in the XUV regime involving the semi–core 3p states. Finally, we compare the relative role of the inverse Faraday effect and the magnetization induced during the absorption of the light and show that the latter plays a prominent role, especially after the light has gone, and in the XUV regime
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Yang, Xingyu. « Manipulating the inverse Faraday effect at the nanoscale ». Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS219.
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Le magnétisme induit par la lumière décrit l'effet par lequel un matériau est magnétisé par une impulsion optique. Dans les matériaux transparents, la magnétisation induite optiquement peut être réalisée directement par la lumière polarisée circulairement. Parfois, dans les matériaux métalliques, ce type de magnétisation existe également en raison du trajet solénoïdal microscopique des électrons entraînés par la lumière polarisée circulairement. Dans certains cas, la lumière crée des courants de dérive continus circulants macroscopiques, qui induisent également une magnétisation continue dans le métal. De manière générale, ces magnétismes induits par la lumière sont connus sous le nom d'effet Faraday inverse. Dans le projet de doctorat, j'ai étudié les courants de dérive induits par la lumière dans plusieurs nanoantennes en or. Nous avons réalisé des champs magnétiques stationnaires amplifiés plasmoniquement grâce à ces courants de dérive. L'étude est basée sur la méthode des différences finies dans le domaine temporel (FDTD) et les théories correspondantes du magnétisme induit par la lumière. Dans différents sujets de recherche, nous avons réalisé : 1) un champ magnétique stationnaire ultra-rapide, confiné et fort dans une nanoantenne en forme d'œil de taureau. 2) Un champ magnétique stationnaire à travers une polarisation linéaire dans un nanorod. 3) Un skyrmion de type Neel construit par un champ magnétique stationnaire dans un nanoring. Dans ces études, nous avons examiné les propriétés optiques de différentes nanoantennes et expliqué l'origine physique des courants de dérive induits par la lumière et des champs magnétiques stationnaires. Nous avons démontré la méthode pour obtenir des effets Faraday inverses amplifiés plasmoniquement et exploré la possibilité de réaliser une magnétisation par la lumière incidente polarisée linéairement. Enfin, nous avons étendu l'effet Faraday inverse à d'autres domaines de recherche physique, tels que la construction de skyrmions par des champs magnétiques stationnaires à travers l'effet Faraday inverse. L'effet magnétique de la lumière reste un domaine de recherche riche. Mes études pourraient trouver des applications dans de nombreux domaines, y compris les matériaux et dispositifs magnéto-optiques, le stockage de données optiques, les applications biomédicales, la spintronique, l'informatique quantique, la recherche fondamentale en électromagnétisme et la recherche sur les matériaux avancésLight-induced magnetism describes the effect where a material is magnetized by an optical pulse. In transparent materials, optically-induced magnetization can be realized directly by circularly polarized light. Sometimes, in metallic materials, this type of magnetization also exists due to the microscopic solenoidal path of electrons driven by circularly polarized light. In some cases, the light creates macroscopic circulating DC drift currents, which also induce DC magnetization in metal. In a broad sense, these light-induced magnetisms are known as the inverse Faraday effect.In the PhD project, I studied light-induced drift currents in multiple gold nanoantennas. We realized plasmonically enhanced stationary magnetic fields through these drift currents. The study is based on the Finite-Difference Time-Domain (FDTD) method and the corresponding light-induced magnetism theories. In different research topics, we have realized: 1) an ultrafast, confined, and strong stationary magnetic field in a bull-eye nanoantenna. 2) A stationary magnetic field through linear polarization in a nanorod. 3) A Neel-type skyrmion constructed by a stationary magnetic field in a nanoring. In these studies, we examined the optical properties of different nanoantennas and explained the physical origin of light-induced drift currents and stationary magnetic fields. We demonstrated the method to achieve plasmonically enhanced inverse Faraday effects and explored the possibility of realizing magnetization through linearly polarized incident light. Finally, we extended the inverse Faraday effect to more physical research areas, such as constructing skyrmions by stationary magnetic fields through the inverse Faraday effect.The magnetic effect of light remains a rich area of research. My studies might find applications in many areas, including magneto-optical materials and devices, optical data storage, biomedical applications, spintronics, quantum computing, fundamental research in electromagnetism, and advanced materials research
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Guo, Wenbin. « Nouveaux composés à conversion de spin et polymorphisme pour une approche multi-échelle vers les hautes T(LIESST) ». Thesis, Bordeaux, 2021. http://www.theses.fr/2021BORD0015.
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L'effet LIESST (Light-Induced Excited Spin-State Trapping) apparaît comme l'un des phénomènes les plus prometteurs et les plus excitants pour les dispositifs applicatifs basés sur les complexes à transition de spin (TS). Cependant, la compréhension fondamentale du LIESST doit encore être approfondie avant toute conception rationnelle. Par exemple, il est encore très difficile d'établir les relations structure-propriétés, bien que cette approche soit cruciale pour découvrir des matériaux à TS ayant une température de relaxation T(LIESST) élevée. L'objectif de ce travail est donc de comprendre comment augmenter la valeur de T(LIESST) vers une plage de température de la vie quotidienne. Nous avons choisi de l’atteindre en tentant d’augmenter la distorsion de la sphère de coordination du métal par deux stratégies basées sur la chimie : i) influer à l'échelle moléculaire via des contraintes stériques induites par des ligands halogénés et ii) moduler la contrainte moléculaire via du polymorphisme. La partie I présente quelques aspects fondamentaux et les parties II et III sont consacrées à la synthèse, à la cristallographie et aux études (photo)magnétiques des nouveaux composés moléculaires, y compris des polymorphes, de la famille [Fe(PM-L)2(NCX)2]. Ces nouveaux composés offrent tout d'abord un large éventail de comportements innovants, comme par exemple des expansions volumiques négatives ou nulles à la TS et l'absence de transition à plusieurs étapes malgré des sites métalliques indépendants au sein du cristal. Ces travaux élargissent considérablement la richesse des perspectives du phénomène de TS. De plus, l'examen approfondi des paramètres pertinents pour l’obtention d’un T(LIESST) élevé, tel que discutés dans la partie IV, apporte de nouvelles caractéristiques et prouve définitivement que toutes les échelles physiques doivent être prises en compte, ce qui conduit à proposer un concept multi-échelle de l'effet LIESSTThe Light-Induced Excited Spin-State Trapping effect (LIESST) appears as one of the most promising and exciting phenomena for applicative devices based on Spin-CrossOver (SCO) complexes. However, the fundamental understanding of the LIESST effect must be yet deeply completed prior to any rational design of any efficient material. For instance, it is still a great challenge to establish the structure-properties relationships corresponding to the LIESST process, though this approach is crucial to discover SCO materials with a high relaxation temperature T(LIESST). The target of this work is therefore to understand how to increase T(LIESST) towards a daily-life temperature range. We choose to reach this goal by increasing the distortion of the metal coordination sphere through two chemistry-based strategies: i) playing at the molecular scale via steric strains produced by halogen-substituted ligands and ii) controlling the molecular stress through polymorphism. Part I displays some fundamental knowledge on SCO and Part II and III are devoted to the synthesis, crystallography and (photo)magnetic studies of new molecular compounds, including polymorphs, of the [Fe(PM-L)2(NCX)2] family. First these new compounds offer a large panel of innovative behaviours, such as, for instance, negative or zero volume expansions at the SCO and the absence of multi-step transition despite independent metal sites within the crystal. This work enlarges significantly the richness of the SCO based perspectives. Second, the deep examination of the relevant parameters to high T(LIESST) as discussed in Part IV brings new features and, overall, definitively proves that all physical scales must be taken into account, leading to a multiscale concept of the LIESST effect
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Seifert, Urban F. P. [Verfasser], Matthias [Gutachter] Vojta et Jörg [Gutachter] Schmalian. « Novel phases and light-induced dynamics in quantum magnets / Urban F. P. Seifert ; Gutachter : Matthias Vojta, Jörg Schmalian ». Dresden : Technische Universität Dresden, 2019. http://d-nb.info/122694485X/34.
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Majumdar, Madhabi. « Elastic Constants, Viscosities and Fluctuation Modes of Certain Bent-Core Nematic Liquid Crystals Studied by Dynamic Light Scattering and Magnetic Field Induced Orientational Distortion ». Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1321991835.
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Barkeloo, Jason T. « Investigation of Electromagnetically Induced Transparency and Absorption in Warm Rb Vapor by Application of a Magnetic Field and Co-propagating Single Linearly Polarized Light Beam ». Miami University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=miami1343962472.
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Real, Elgueda Bastián Maximiliano. « Transport and driven-dissipative localization in exciton-polariton lattices ». Electronic Thesis or Diss., Université de Lille (2022-....), 2022. http://www.theses.fr/2022ULILR025.
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La simulation des Hamiltoniens de réseaux dans les plateformes photoniques a permis de mieux comprendre les nouvelles propriétés de transport et de localisation dans le contexte de la physique de l'état solide. En particulier, les exciton-polaritons constituent un système polyvalent permettant d'étudier ces propriétés dans des réseaux avec des structures de bande intrigantes en présence de pertes et de gains, et d'interactions entre particules. Les polaritons sont des quasi-particules hybrides lumière-matière résultant du couplage fort entre les photons et les excitons dans les microcavités semi-conductrices, dont les propriétés peuvent être directement accessibles dans les expériences de photoluminescence. Dans cette thèse, nous étudions premièrement les caractéristiques des réseaux en nid d'abeille déformés, composés de résonateurs de polaritons couplés, à haut contenu photonique. Dans un réseau déformé de façon critique, nous mettons en évidence à la fois un transport semi-Dirac et une localisation anisotrope des photons. Deuxièmement, nous montrons qu'un forçage judicieux dans des réseaux de résonateurs à pertes permet l'apparition de nouveaux modes localisés. En utilisant des réseaux de polaritons sous un forçage résonant par plusieurs faisceaux optiques, nous démontrons la possibilité de localiser la lumière sur différentes géométries, voir jusqu'à un seul site. Enfin, nous profitons de l'interaction de polaritons dépendant de la polarisation pour démontrer un effet optique de type Zeeman dans un seul micropilier. En combinant le couplage spin-orbite optique, inhérent aux microstructures semi-conductrices, avec l'effet Zeeman, induit par l'interaction, nous montrons l'émission de faisceaux de vortex avec une chiralité bien définie. Cette thèse met en lumière la puissance des plateformes de polaritons pour étudier les Hamiltoniens de réseaux avec des propriétés sans précédent. Elle apporte également un premier pas vers la génération, entièrement optique, de phases topologiques dans les réseauxThe simulation of lattice Hamiltonians in photonic platforms has been enlightening in the understanding of novel transport and localization properties in the context of solid-state physics. In particular, exciton-polaritons provide a versatile system to investigate these properties in lattices with intriguing band structures in the presence of gain and loss, and particle interactions. Polaritons are hybrid light-matter quasiparticles arising from the strong coupling between photons and excitons in semiconductor microcavities, whose properties can be directly accessed in photoluminescence experiments. In this thesis, we firstly study the features of strained honeycomb lattices made of coupled polariton resonators having high photonic content. In a critically strained lattice, we evidence both a semi-Dirac transport and an anisotropic localization of photons. Secondly, we show that a judicious driving in lattices of lossy resonators allows the appearance of novel localized modes. Using polariton lattices driven resonantly with several optical beams, we demonstrate the localization of light in at-will geometries down to a single site. Finally, we take advantage of the polarization-dependent polariton interaction to demonstrate an optical Zeeman-like effect in a single micropillar. In combination with optical spin-orbit coupling inherent to semiconductor microstructures, the interaction-induced Zeeman effect results in emission of vortex beams with a well-defined chirality. This thesis brings to light the power of polariton platforms to study lattice Hamiltonians with unprecedented properties and it also provides a first step towards the fully-optical generation of topological phases in lattices
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Bhattarai, Mangesh. « Light and magnetic field induced coherence effects in atoms ». Thesis, 2020. https://etd.iisc.ac.in/handle/2005/4932.
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In this thesis, we have studied the coherence effects in atoms induced by light and a magnetic field. After giving an introduction to the contents of the thesis, details about the theory and the experimental setup used are given. The next few chapters contain the experimental results backed by a theoretical understanding. Only the joint work with the Armenian group (paper titled “Study of EIT resonances in an anti-relaxation coated Rb vapor cell” published in Physics Letters A) is one where they did the experiment and we did the theory. The thesis ends with a discussion about the various results presented.
In the first work, the magnetic field induced coherence effect is studied in the light of the Hanle effect. We have studied the transformation of a Hanle EIT to a Hanle EIA for a circularly polarized beam in presence of a spatially separated control beam whose ellipticity is varied. A density matrix model describing three regions of interaction is developed to reproduce the experimental results.
The second work describes the use of CPT/EIT system in a double-lambda configuration to interfere beams in one lambda system while the other lambda system acts as a phase reference. This process of light interference mediated by atomic coherence is extended to propose a system in which interference between two beams 10s of GHz apart in frequency could be detected on a low bandwidth (10s of MHz) optical detector.
The third work describes an observation of EIA in a vee + ladder system in 87Rb. The vee system is formed by using the D1 line of 87Rb as control and the D2 line as the probe, and the ladder system is formed by the same probe as in vee system and a beam on the transition from 5P3/2 to 5D5/2 as control.
The fourth work, done along with our collaborators in Armenia, shows splitting of EIT into dark and bright resonance in the presence of a strong transverse magnetic field in an anti-relaxation coated cell in the D1 line of 87Rb. We have performed a density matrix analysis using all the magnetic sublevels to reproduce the experimental results. The tunability of such a system between super-luminal and sub-luminal propagation for a probe beam is also theoretically discussed.
9
Seifert, Urban F. P. « Novel phases and light-induced dynamics in quantum magnets ». 2019. https://tud.qucosa.de/id/qucosa%3A36749.
Texte intégralRésumé :
In this PhD thesis, we study the interplay between symmetry-breaking order and quantum-disordered phases in the milieu of frustrated quantum magnets, and further show how the excitation process of long-wavelength (semi-)classical modes in spin-orbit coupled antiferromagnets crucially depends on the nature and interactions of the underlying quantum quasiparticles.
First, we focus on Kitaev's exactly solvable model for a Z2 spin liquid as a building block for constructing novel phases of matter, utilizing Majorana mean-field theory (MMFT) to map out phase diagrams and study occurring phases.
In the Kitaev Kondo lattice, conduction electrons couple via a Kondo interaction to the local moments in the Kitaev model.
We find at small Kondo couplings a fractionalized Fermi liquid (FL*) phase, a stable non-Fermi liquid where conventional electronic quasiparticles coexist with the deconfined excitations of the spin liquid.
The transition between FL* and a conventional Fermi liquid is masked by an exotic (confining) superconducting phase which exhibits nematic triplet pairing, which we argue to be mediated by the Majorana fermions in the Kitaev spin liquid.
We moreover study bilayer Kitaev models, where two Kitaev honeycomb spin liquids are coupled via an antiferromagnetic Heisenberg interaction.
Varying interlayer coupling and Kitaev coupling anisotropy, we find both direct transitions from the spin liquid to a trivial dimer paramagnet as well as intermediate 'macrospin' phases, which can be studied by mappings to effective transverse-field Ising models.
Further, we find a novel interlayer coherent pi-flux phase.
Second, we consider the stuffed honeycomb Heisenberg antiferromagnet, where recent numerical studies suggest the coexistence of collinear Néel order and a correlated paramagnet, dubbed 'partial quantum disorder'.
We elucidate the mechanism which drives the disorder in this model by perturbatively integrating out magnons to derive an effective model for the disordered sublattice.
This effective model is close to a transition between two competing ground states, and we conjecture that strong fluctuations associated with this transition lead to disorder.
Third, we study the generation of coherent low-energy magnons using ultrafast laser pulses in the spin-orbit coupled antiferromagnet Sr2IrO4, inspired by recent pump-probe experiments. While the relaxation dynamics of the system at long time scales can be well described semi-classically, the ultrafast excitation process is inherently non-classical.
Using symmetry analysis to write down the most general coupling between electric field and spin operators, we subsequently integrate out high-energy spin fluctuations to derive induced effective fields which act to excite the low-energy magnon, constituting a generalized 'inverse Faraday effect'.
Our theory reveals a tight relationship between induced fields and the two-magnon density of states.:1 Introduction
1.1 Frustrated antiferromagnets
1.2 Quantum spin liquids
1.3 Fractionalization and topological order
1.4 Spin-orbit coupling
1.5 Outline
I Novel phases by building on Kitaev’s honeycomb model
2 Kitaev honeycomb spin liquid
2.1 Microscopic spin model and constants of motion
2.2 Majorana representation of spin algebra
2.3 Exact solution
2.3.1 Ground state
2.3.2 Correlations and dynamics
2.3.3 Thermodynamic properties
2.4 Z2 gauge structure
2.5 Toric code
2.6 Topological order
2.6.1 Superselection sectors and ground-state degeneracy
2.6.2 Topological entanglement entropy
2.6.3 Symmetry-enriched and symmetry-protected topological phases
3 Mean-field theory
3.1 Generalized spin representations
3.1.1 Parton constructions
3.1.2 SO(4) Majorana representation
3.2 Projective symmetry groups
3.3 Mean-field solution of the Kitaevmodel
3.4 Comparisonwithexactsolution
3.4.1 Spectral properties
3.4.2 Correlation functions
3.4.3 Thermodynamic properties
3.5 Generalized decoupling
3.6 Comparison to previous Abrikosov fermion mean-field theories of the Kitaev model
3.7 Discussion
4 Fractionalized Fermi liquids and exotic superconductivity
in the Kitaev Kondo lattice
4.1 Metals with frustration
4.2 Local-moment formation and Kondo effect
4.2.1 Single Kondo impurity
4.2.2 Kondo lattices and heavy Fermi liquids
4.3 Fractionalized Fermi liquids
4.4 Construction of the Kitaev Kondo lattice
4.4.1 Hamiltonian
4.4.2 Symmetries
4.5 Mean-field decoupling of Kondo interaction
4.5.1 Solution of self-consistency conditions
4.6 Overview of mean-field phases
4.7 Fractionalized Fermi liquid
4.7.1 Results from mean-field theory
4.7.2 Perturbation theory beyond mean-field theory
4.8 Heavy Fermi liquid
4.9 Superconducting phases
4.9.1 Spontaneously broken U(1) phase rotation symmetry
4.9.2 Excitation spectrum and nematicity
4.9.3 Topological triviality
4.9.4 Group-theoretical classification
4.9.5 Pairing glue
4.10 Comparison with a subsequent study
4.11 Discussion and outlook
5 Bilayer Kitaev models
5.1 Model and stacking geometries
5.1.1 Hamiltonian
5.1.2 Symmetries and conserved quantities
5.2 Previous results
5.3 Mean-field decoupling and phase diagrams
5.3.1 AA stacking
5.3.2 AB stacking
5.3.3 σAC stacking
5.3.4 σ ̄AC stacking
5.4 Quantum phase transition in the AA stacking
5.4.1 Perturbative analysis
5.5 Phase transition in the σAC stacking
5.6 Macro-spin phases
5.6.1 KSL-MAC transition: Effective model for Kitaev dimers
5.6.2 DIM-MAC transition: Effective theory for triplon condensation
5.6.3 Macro-spin interactions and series expansion results
5.6.4 Antiferromagnet in the AB stacking
5.7 Stability of KSL and the interlayer-coherent π-flux phase
5.7.1 Perturbative stability of the Kitaev spin liquid
5.7.2 Spontaneous interlayer coherence near the isotropic point
5.8 Summary and discussion
II Partial quantum disorder in the stuffed honeycomb lattice
6 Partial quantum disorder in the stuffed honeycomb lattice
6.1 Definition of the stuffed honeycomb Heisenberg antiferromagnet
6.2 Previous numerical results
6.3 Derivation of an effective model
6.3.1 Spin-wave theory for the honeycomb magnons
6.3.2 Magnon-central spin vertices
6.3.3 Perturbation theory
6.3.4 Instantaneous approximation
6.3.5 Truncation of couplings
6.3.6 Single-ion anisotropy
6.3.7 Discussion of most dominant interactions
6.4 Analysis of effective model
6.4.1 Classical ground states
6.4.2 Stability of classical ground states in linear spin-wave theory
6.4.3 Minimal model for incommensurate phase
6.4.4 Discussion of frustration mechanism in the effective model
6.5 Partial quantum disorder beyond the effectivemodel
6.5.1 Competition between PD and the (semi-)classical canted state
6.5.2 Topological aspects
6.5.3 Experimental signatures
6.6 Discussion
6.6.1 Directions for further numerical studies
6.6.2 Experimental prospects
III Optical excitation of coherent magnons
7 Ultrafast optical excitation of magnons in Sr2IrO4
7.1 Pump-probe experiments
7.2 Previous approaches to the inverse Faraday effect and theory goals
7.3 Sr2IrO4 as a spin-orbit driven Mott insulator
7.4 Spin model for basal planes in Sr2IrO4
7.4.1 Symmetry analysis
7.4.2 Classical ground state and linear spin-wave theory
7.4.3 Mechanism for in-plane anisotropy
7.5 Pump-induced dynamics
7.5.1 Coupling to the electric field: Symmetry analysis
7.5.2 Keldysh path integral
7.5.3 Low-energy dynamics
7.5.4 Driven low-energy dynamics
7.6 Derivation of the induced fields
7.6.1 Perturbation theory
7.6.2 Evaluation of loop diagram
7.6.3 Analytical momentum integration in the continuum limit
7.6.4 Numerical evaluation of effective fields
7.7 Analysis of induced fields
7.7.1 Polarization and angular dependence
7.7.2 Two-magnon spectral features
7.8 Applications to experiment
7.8.1 Predictions for experiment
7.8.2 Magnetoelectrical couplings
7.9 Discussion and outlook
8 Conclusion and outlook
8.1 Summary
8.2 Outlook
IV Appendices
A Path integral methods
B Spin-wave theory
B.1 Holstein-Primakoff bosons
B.2 Linear spin-wave theory
B.2.1 Diagonalization via Bogoliubov transformation
B.2.2 Applicability of linear approximation
B.3 Magnon-magnon interactions
B.3.1 Dyson's equation and 1/S consistency
B.3.2 Self-energy from quartic interactions in collinear states on bipartite lattices
C Details on the SO(4) Majorana mean-field theory
C.1 SO(4) Matrix representation of SU(2) subalgebras
C.2 Generalized SO(4) Majorana mean-field theory for a Heisenberg dimer
(Chapter 3)
C.3 Dimerization of SO(4) Majorana mean-field for the Kitaev model
(Chapter3)
C.4 Mean-field Hamiltonian in the Kitaev Kondo lattice (Chapter 4)
C.5 Example solutions in the superconducting phase for symmetry analysis
(Chapter4)
D Linear spin-wave theory for macrospin phase in the bilayer Kitaev model
(Chapter 5)
D.1 Spin-wave Hamiltonian and Bogoliubov rotation
D.2 Results and discussion
E Extrapolation of the effective couplings for the staggered field h -> 0
(Chapter 6)
E.1 xy interaction
E.1.1 Leadingorder ~ S0
E.1.2 Subleadingorder ~ S^(−1)
E.2 z-Ising interaction
F Light-induced fields by analytical integration (Chapter 7)
F.1 Method
F.2 Results
Bibliography
10
Pashkevich, Mikhail. « Ultrafast light-induced magnetization dynamics in Co/garnet heterostructures ». Phd thesis, 2015. http://hdl.handle.net/11320/2612.
Texte intégralRésumé :
Wydział Fizyki.The goal of the thesis is to addree the interaction of light with Co/garnet heterostructures, in order to achieve an understanding in this area that we call "femtomagnetism". In Chapter I, an introduction to ultrafast dynamics is presended. Chapter II gives short overview of magnetic properties with the focus on photomagnetism in garnets. Chapter III provides the basic introduction into the experimental techniques. In Chapter IV, we demostrate how damage-free etching of garrnet films allows us to form the Co/garnet heterostructures. In Chapter V the magnetic and magneto-optical properties of Co/garnet heterostructures were presented. Chapter VI deals studies of surface/interfaces in heterostructures in a wide spectral range. In Chapter VII, we demonstrate the results laser-induced magnetization dynamics, photoinduced magnetic anisotropy in bare garnet films and modulation of spin precession in Co/garnet heterostructures. Furthermore, it is shown that the magnetisation precession in the garnet film can be manipulated by the strong magnetostatic coupling between Co and garnet layers. These findings could provide new possibilities in optical excitation and local spin manipulation by polarized femtosecond pulses for the application in the new magnetic storage memory with high speed recording.
Głównym celem niniejszej rozprawy są badania oddziaływania światła laserowego z heterostrukturą Co/granat, jak również głębsze zrozumienie zjawisk fizyki magnetyzmu w skali femtosekundowej - tzw. "femtomagnetyzmu". Rozdział I obejmuje wprowadzenie do ultraszybkiej dynamiki magnetyzacji. W Rozdziale II umieszczono krótki przegląd właściwości magnetycznych oraz zjawiska fotomagnetyzmu w cienkich warstwach granatów itrowo-żelazowych. W Rozdziale III opisano główne techniki eksperymentalne. W Rozdziale IV przedstawiono metodę wytworzenia magnetycznych heterostruktur kobalt/granat o różnych grubościach. Rozdział V zawiera opis podstawowych właściwości magnetooptycznych i magnetycznych heterostruktur. W Rozdziale VI przedstawiono wyniki badań spektralnych powierzchni/interfejsów heterostruktur. Rozdział VII prezentuje wyniki badań ultraszybkiej dynamiki magnetyzacji, fotoindukowanej anizotropii w warstwach granatu oraz efekt modulacji precesji spinów w heterostrukturze Co/granat. Także zaobserwowano zmianę fazy precesji magnetyzacji w warstwie granatu w zakresie sprzężenia magnetostatycznego z warstwą kobaltu. Zawarte w rozprawie wyniki, prezentujące szerokie możliwości wzbudzeń optycznych oraz lokalną manipulację spinem przy wykorzystaniu spolaryzowanego światła laserowego, rokują nadzieje na zastosowania w nowych pamięciach magnetycznych o dużej szybkości zapisu.
The work described in this thesis was financially supported by the EU 7 Framework Programme (FP7/2007- 2013) under grant agreement No. 214810 (FANTOMAS), the SYMPHONY project operated within the Foundation for Polish Science Team Program co-financed by the EU European Regional Development Fund, OPIE 2007-2013 and the National Science Centre Poland for OPUS project DEC-2013/09/B/ST3/02669.
Livres sur le sujet "Light-Induced magnetism"
1
Adapa, Ram, et Anthony Absalom. Central nervous system physiology in anaesthetic practice. Sous la direction de Jonathan G. Hardman. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199642045.003.0006.
Texte intégralRésumé :
How and where consciousness is generated and maintained remains an unsolved scientific mystery, and this has impeded progress in understanding anaesthesia. In recent years, however, significant progress has been made in understanding the neurobiology of anaesthetic-induced loss of consciousness. This has been made possible by advances in molecular biology techniques, which have helped shed light on the molecular mechanisms of action of the anaesthetic agents. In parallel, the development of neuroimaging techniques, such as functional magnetic resonance imaging and positron emission tomography, has also provided an enormous impetus. These techniques are providing new insights into the neural correlates of consciousness, and new insights into the alterations in neurophysiology associated with impaired consciousness caused by sleep, sedation, and anaesthesia. The information being gained from these studies on the neurobiology of impairments of attention, awareness, and memory will hopefully eventually not only lead to improvements in our understanding of consciousness and anaesthesia, but also to better clinical care. Understanding of memory functions during sedation and anaesthesia may, for example, lead to better strategies for preventing awareness with subsequent explicit recall of intraoperative events. Further, a better understanding of the neurobiology of anaesthetic-induced unconsciousness may inform future development of better anaesthetic agents, with a broader therapeutic index, and fewer unwanted effects.
2
Rai, Dibya Prakash, dir. Advanced Materials and Nano Systems : Theory and Experiment - Part 2. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/97898150499611220201.
Texte intégralRésumé :
The discovery of new materials and the manipulation of their exotic properties for device fabrication is crucial for advancing technology. Nanoscience, and the creation of nanomaterials have taken materials science and electronics to new heights for the benefit of mankind. Advanced Materials and Nanosystems: Theory and Experiment covers several topics of nanoscience research. The compiled chapters aim to update students, teachers, and scientists by highlighting modern developments in materials science theory and experiments. The significant role of new materials in future technology is also demonstrated. The book serves as a reference for curriculum development in technical institutions and research programs in the field of physics, chemistry and applied areas of science like materials science, chemical engineering and electronics. This part covers 12 topics in these areas: 1. Recent advancements in nanotechnology: a human health Perspective 2. An exploratory study on characteristics of SWIRL of AlGaAs/GaAs in advanced bio based nanotechnological systems 3. Electronic structure of the half-Heusler ScAuSn, LuAuSn and their superlattice 4. Recent trends in nanosystems 5. Improvement of performance of single and multicrystalline silicon solar cell using low-temperature surface passivation layer and antireflection coating 6. Advanced materials and nanosystems 7. Effect of nanostructure-materials on optical properties of some rare earth ions doped in silica matrix 8. Nd2Fe14B and SmCO5: a permanent magnet for magnetic data storage and data transfer technology 9. Visible light induced photocatalytic activity of MWCNTS decorated sulfide based nano photocatalysts 10. Organic solar cells 11. Neodymium doped lithium borosilicate glasses 12. Comprehensive quantum mechanical study of structural features, reactivity, molecular properties and wave function-based characteristics of capmatinib
Chapitres de livres sur le sujet "Light-Induced magnetism"
1
Kojima, Norimichi, et Atsushi Okazawa. « Molecular Magnetism of Metal Complexes and Light-Induced Phase Transitions ». Dans Topics in Applied Physics, 267–317. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-9422-9_6.
Texte intégral
2
Imoto, Kenta. « Observation of Light-Induced Spin-Crossover Magnetism in a Fe-[Nb(CN)8] Bimetal Assembly ». Dans Multifunctional Molecular Magnets Based on Octacyanidometalates, 29–46. Singapore : Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-6135-6_2.
Texte intégral
3
Mosiniewicz-Szablewska, E. « Light-Induced Changes in the FMR Parameters of CdCr2Se4 ». Dans 25th Congress Ampere on Magnetic Resonance and Related Phenomena, 46–47. Berlin, Heidelberg : Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-76072-3_21.
Texte intégral
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Krenn, H. « Light-Induced Magnetization in Dilute Magnetic PbTe/PbMnTe Quantum Well Structures ». Dans Localization and Confinement of Electrons in Semiconductors, 342–52. Berlin, Heidelberg : Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-84272-6_36.
Texte intégral
5
Shahinpoor, Mohsen. « Shape Memory Polymers (SMPs) as Smart Materials ». Dans Fundamentals of Smart Materials, 160–69. The Royal Society of Chemistry, 2020. http://dx.doi.org/10.1039/bk9781782626459-00160.
Texte intégralRésumé :
Chapter 14 reviews shape memory polymers (SMPs). Shape memory polymers belong to the family of shape memory materials (SMMs), which can be deformed into a predetermined shape under some imposed specific conditions such as temperature, electric or magnetic field, as well as strain and stress. These shapes can be relaxed back to their original field-free shapes under thermal, electrical, magnetic, strain, stress, temperature, laser, or environmental stimuli. These transformations are essentially due to the elastic energy stored in SMMs during initial deformation. As a member of SMMs, SMPs are stimuli-sensitive polymers. Shape memory polymers normally use either heat or laser light energy as a stimulant to change shape. The thermally-induced shape memory effect can be observed by irradiation with infrared light, exposure to alternating magnetic fields, application of an electric field or immersion in water.
6
Freeman, Ray. « Detection of magnetic resonance ». Dans Magnetic Resonance in Chemistry and Medicine, 33–53. Oxford University PressOxford, 2003. http://dx.doi.org/10.1093/oso/9780199260614.003.0003.
Texte intégralRésumé :
Abstract We first observe the magnetic resonance response from the nuclei as a tiny voltage induced on a coil surrounding the sample-the receiver coil. How does this arise? In most forms of spectroscopy there are three possible mechanisms to describe the interaction of radiation with matter. Stimulated absorption or stimulated emission describe the absorption or emission of radiation by the sample provoked by the radiation field itself. Spontaneous emission occurs in the absence of any imposed radiation field, for example, the light emitted from a heated metallic filament. Spontaneous emission is far too weak an effect to be relevant to magnetic resonance experiments. The free precession NMR signal occurs after extinction of the radiofrequency pulse used for excitation and subsequently evolves in the absence of any imposed radiation field, so none of these three phenomena can properly account for magnetic resonance signals.
7
Lippmann, Morton, Beverly S. Cohen et Richard B. Schlesinger. « Nonionizing Electromagnetic Radiation ». Dans Environmental Health Science, 310–30. Oxford University PressNew York, NY, 2003. http://dx.doi.org/10.1093/oso/9780195083743.003.0010.
Texte intégralRésumé :
Abstract Electromagnetic radiation is emitted from sources in space and from anthropogenic sources on earth. It travels at a constant speed, i.e., the speed of light. The overall electromagnetic spectrum is illustrated in Figure 10–1. Energy is transmitted as a sinusoidal wave form, by time varying electric and magnetic fields. The transmission velocity, c, is described by the formula: The health effects of exposures to the various components of the electromagnetic spectrum vary greatly with frequency, and the discussion that follows outlines the sources, as well as the nature and extent of the effects that they produce. There are separate discussions on component bands within the overall spectrum, i.e., ionizing radiation, UV, visible, IR, and radio frequency (RF). The electric and magnetic fields induced by these radiations can also produce biological responses, and these responses will also be reviewed.
8
Mark, J. Winter. « Consequences of d orbital splitting ». Dans d-Block Chemistry. Oxford University Press, 2015. http://dx.doi.org/10.1093/hesc/9780198700968.003.0007.
Texte intégralRésumé :
This chapter describes properties, such as colour and unusual magnetic properties, of d-block metal complexes. It points out that if a compound contains an electron in the lower of two energy levels, then irradiation of that compound with light whose energy is equal to the energy gap between the two levels. The chapter also reviews orbitals that possess a centre of symmetry when a molecule possesses a centre of symmetry that are gerade (g). The chapter talks about photochemically induced d–d transitions that are governed by the Laporte symmetry selection rule and by the spin selection rule. It discusses Jahn–Teller distortions that arise when the electron occupancy of a degenerate set of energy levels is asymmetric.
9
Castel, B., et I. S. Towner. « Single-Particle and Shell-Model Theories of Quadrupole Moments ». Dans Modern Theories of Nuclear Moments, 188–211. Oxford University PressOxford, 1990. http://dx.doi.org/10.1093/oso/9780198517283.003.0006.
Texte intégralRésumé :
Abstract We now turn our attention to electric quadrupole moments. These moments have traditionally been invoked as good indicators of collective effects in contrast to magnetic moments. The reason for that is simple and has to do with the difference in the nature of the two relevant operators. The magnetic dipole operator leads to opposite contributions from a state |ψ⟩ and its time-reversed conjugate |ψ˜⟩ (since both currents and spin change sign in the |ψ⟩→|ψ˜⟩ conjugation). Thus one member of the paired-off nucleon cancels the contribution from the other. Such is not the case for the quadrupole operator since its contributions are invariant under time reversal. Thus if nuclear correlations can be induced by some deformation, a coherent buildup of quadrupole moment can be expected. As we shall see, this coherence can lead to sizeable effects which will be examined in this chapter in the light of single-particle and various shell models. The next chapter will be devoted to a survey of the macroscopic models currently available for the study of quadrupole moments and nuclear deformations.
10
Peri, Angela Denise. « A Smart Materials Driven Approach to the Interior Design of Cruise Ships ». Dans Progress in Marine Science and Technology. IOS Press, 2023. http://dx.doi.org/10.3233/pmst230027.
Texte intégralRésumé :
The cruise ship unit is often defined as a “floating city” where the presence of large, open and closed spaces reproduces, in terms of dimensions and functions, those of public and private civil architecture. The aim of this research activity is to identify a theoretical process of mutual interaction among these two fields and functional links between material, technology and design, starting from a scoping activity review of the currently constituent finishing materials. This can lead to a possible application of adaptive solutions, which mainly rely on the use of smart materials, where external stimuli induced by electric, magnetic, mechanical and thermal fields of force, as well as variations in environmental parameters (temperature, pH, humidity, lightness, noise and the possible presence of harmful substances) give rise to an active, reversible response which causes variations of the intrinsic properties as well as a change in their structure, composition, function or shape. All the potential applications will have to assess the compatibility with the marine environment, durability and compliance with the rules and include performance paints and inks, photocatalytic systems with self-sanitizing properties, fabrics with antibacterial and water-repellent properties which, together with a protective action, able to generate electricity if exposed to light. Some polymeric fibres can thermally modify their sensitivity to humidity and allow for better adaptability and reversible shrinkage; self-healing surfaces regenerate after the occurrence of a crack. It is possible to create devices integrated with sensors and actuators capable of reacting automatically, monitoring the status of an electronic system and to detect specific environmental and human parameters. These applications are shaping a new perception of reality which include intelligent materials as elements of a new design-driven language, where all the phases of the concept design become interactive, adaptive and conscious, in closer affinity with the dynamics of living beings.
Actes de conférences sur le sujet "Light-Induced magnetism"
1
Adamantopoulos, Theodoros, Maximilian Merte, Dongwook Go, Frank Freimuth, Stefan Blügel et Yuriy Mokrousov. « Optically induced orbital magnetism in light materials ». Dans Spintronics XVII, sous la direction de Henri Jaffrès, Jean-Eric Wegrowe, Manijeh Razeghi et Joseph S. Friedman, 128. SPIE, 2024. http://dx.doi.org/10.1117/12.3035719.
Texte intégral
2
Abedi, S., et A. H. Majedi. « Light-induced Magnetic Field in Graphene ». Dans 2024 Photonics North (PN), 1–2. IEEE, 2024. http://dx.doi.org/10.1109/pn62551.2024.10621828.
Texte intégral
3
Sheldon, Matthew T. « Active tuning of plasmon damping via light induced magnetism (Conference Presentation) ». Dans Metamaterials, Metadevices, and Metasystems 2022, sous la direction de Nader Engheta, Mikhail A. Noginov et Nikolay I. Zheludev. SPIE, 2022. http://dx.doi.org/10.1117/12.2638117.
Texte intégral
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Sheldon, Matthew T. « Ultrafast light-induced magnetism and non-reciprocity in plasmonic Au nanoparticles (Conference Presentation) ». Dans Smart Photonic and Optoelectronic Integrated Circuits XXII, sous la direction de Sailing He et Laurent Vivien. SPIE, 2020. http://dx.doi.org/10.1117/12.2551182.
Texte intégral
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Sheldon, Matthew T., et Oscar Hsu-Cheng Cheng. « 1,000-fold enhancement of light-induced magnetism in plasmonic Au nanoparticles (Conference Presentation) ». Dans Metamaterials, Metadevices, and Metasystems 2019, sous la direction de Nader Engheta, Mikhail A. Noginov et Nikolay I. Zheludev. SPIE, 2019. http://dx.doi.org/10.1117/12.2529704.
Texte intégral
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Leng, Jinsong, Yanju Liu et Shanyi Du. « Shape Memory Polymers : A Potential Material for Future’s Changing Shape ». Dans ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2010. http://dx.doi.org/10.1115/smasis2010-3709.
Texte intégralRésumé :
Shape memory polymers (SMPs) undergo significant macroscopic deformation upon the application of an external stimulus. As a novel and promising kind of smart materials, they have been widely researched since the 1980s. SMPs present many potential technical advantages that surpass those of shape memory alloys and shape memory ceramics such as good shape recoverability, low density, ease in processing and in tailoring of properties (e.g., transition temperature, stiffness, bio-degradability, and ease of functionally grading), programmability and controllability of recovery behavior, and most importantly, low cost. This paper aims to provide a comprehensive review of SMPs, encompassing a fundamental understanding of the shape memory of SMPs. The synthesis of SMPs is presented firstly. In order to realize the actuation of SMPs for a special application, the investigation of actuations in multi ways are performed, namely electroactive SMPs, light-responsive SMPs, magnetism-induced SMPs, and chemo-responsive SMPs. These novel actuation approaches play a critical role in the development of multifunctional materials that not only exhibit the shape memory effect but also perform particular functions. Based on the unique properties of such materials, primary applications are also listed, and the potential directions and applications of SMPs are proposed to be developed in future research.
7
Raikher, Y. L., V. I. Stepanov, S. V. Burylov et Y. N. Skibin. « AC field induced modulation of the light in a magnetic fluid ». Dans International Magnetics Conference. IEEE, 1989. http://dx.doi.org/10.1109/intmag.1989.690210.
Texte intégral
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Dadoenkova, N. N., I. L. Lyubehanskii, M. I. Lyubehanskii, Th Rasing et Sung-Chul Shin. « Misfit strain induced reflection of light from magnetic-nonmagnetic interfaces ». Dans IEEE International Magnetics Conference. IEEE, 1999. http://dx.doi.org/10.1109/intmag.1999.837957.
Texte intégral
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Neufeld, Ofer, Nicolas Tancogne-Dejean, Umberto De Giovannini, Hannes Hübener et Angel Rubio. « Nonlinear Light-Induced Attosecond Magnetization Dynamics in Non-Magnetic Materials ». Dans 2023 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC). IEEE, 2023. http://dx.doi.org/10.1109/cleo/europe-eqec57999.2023.10231467.
Texte intégral
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Davidenko, I. I., M. Fally, R. A. Rupp et B. Sugg. « Magnetic and Optical Anisotropy in Garnets Induced by Linearly Polarized Light ». Dans Photorefractive Effects, Materials, and Devices. Washington, D.C. : OSA, 2001. http://dx.doi.org/10.1364/pemd.2001.528.
Texte intégralRapports d'organisations sur le sujet "Light-Induced magnetism"
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Johra, Hicham. Performance overview of caloric heat pumps : magnetocaloric, elastocaloric, electrocaloric and barocaloric systems. Department of the Built Environment, Aalborg University, janvier 2022. http://dx.doi.org/10.54337/aau467469997.
Texte intégralRésumé :
Heat pumps are an excellent solution to supply heating and cooling for indoor space conditioning and domestic hot water production. Conventional heat pumps are typically electrically driven and operate with a vapour-compression thermodynamic cycle of refrigerant fluid to transfer heat from a cold source to a warmer sink. This mature technology is cost-effective and achieves appreciable coefficients of performance (COP). The heat pump market demand is driven up by the urge to improve the energy efficiency of building heating systems coupled with the increase of global cooling needs for air-conditioning. Unfortunately, the refrigerants used in current conventional heat pumps can have a large greenhouse or ozone-depletion effect. Alternative gaseous refrigerants have been identified but they present some issues regarding toxicity, flammability, explosivity, low energy efficiency or high cost. However, several non-vapour-compression heat pump technologies have been invented and could be promising alternatives to conventional systems, with potential for higher COP and without the aforementioned refrigerant drawbacks. Among those, the systems based on the so-called “caloric effects” of solid-state refrigerants are gaining large attention. These caloric effects are characterized by a phase transition varying entropy in the material, resulting in a large adiabatic temperature change. This phase transition is induced by a variation of a specific external field applied to the solid refrigerant. Therefore, the magnetocaloric, elastocaloric, electrocaloric and barocaloric effects are adiabatic temperature changes in specific materials when varying the magnetic field, uniaxial mechanical stress, electrical field or hydrostatic pressure, respectively. Heat pump cycle can be built from these caloric effects and several heating/cooling prototypes were developed and tested over the last few decades. Although not a mature technology yet, some of these caloric systems are well suited to become new efficient and sustainable solutions for indoor space conditioning and domestic hot water production. This technical report (and the paper to which this report is supplementary materials) aims to raise awareness in the building community about these innovative caloric systems. It sheds some light on the recent progress in that field and compares the performance of caloric systems with that of conventional vapour-compression heat pumps for building applications.