Dissertations / Theses on the topic 'Semimetals'
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Trescher, Maximilian [Verfasser]. "Tilted Weyl Semimetals / Maximilian Trescher." Berlin : Freie Universität Berlin, 2018. http://d-nb.info/1176708244/34.
Full textMcCormick, Timothy M. "Electronic and Transport Properties of Weyl Semimetals." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu153204408441858.
Full textZhong, Shudan. "Linear and Nonlinear Electromagnetic Responses in Topological Semimetals." Thesis, University of California, Berkeley, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13421373.
Full textThe topological consequences of time reversal symmetry breaking in two dimensional electronic systems have been a focus of interest since the discovery of the quantum Hall effects. Similarly interesting phenomena arise from breaking inversion symmetry in three dimensional systems. For example, in Dirac and Weyl semimetals the inversion symmetry breaking allows for non-trivial topological states that contain symmetry-protected pairs of chiral gapless fermions. This thesis presents our work on the linear and nonlinear electromagnetic responses in topological semimetals using both a semiclassical Boltzmann equation approach and a full quantum mechanical approach. In the linear response, we find a ``gyrotropic magnetic effect" (GME) where the current density $j
B$ in a clean metal is induced by a slowly-varying magnetic field. It is shown that the experimental implications and microscopic origin of GME are both very different from the chiral magnetic effect (CME). We develop a systematic way to study general nonlinear electromagnetic responses in the low-frequency limit using a Floquet approach and we use it to study the circular photogalvanic effect (CPGE) and second-harmonic generation (SHG). Moreover, we derive a semiclassical formula for magnetoresistance in the weak field regime, which includes both the Berry curvature and the orbital magnetic moment. Our semiclassical result may explain the recent experimental observations on topological semimetals. In the end, we present our work on the Hall conductivity of insulators in a static inhomogeneous electric field and we discuss its relation to Hall viscosity.
Kim, Namshik. "Holographic gauge/gravity duality and symmetry breaking in semimetals." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/60622.
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Physics and Astronomy, Department of
Graduate
Bennacer, Badis. "Acoustic plasmons and transverse modes in semimetals and semiconductors." Thesis, University of East Anglia, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280013.
Full textChu, Ruilin, and 储瑞林. "Numerical study of topological insulators and semi-metals." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47163252.
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Physics
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Doctor of Philosophy
Mao, Ting, and 毛汀. "Theoretical studies of topological DIII-class chains and Weyl semimetals / y Ting Mao, MSci. Nanjing University." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2015. http://hdl.handle.net/10722/212613.
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Physics
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Doctor of Philosophy
Villanova, John William. "Examining Topological Insulators and Topological Semimetals Using First Principles Calculations." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82959.
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Sbierski, Björn [Verfasser]. "On disorder effects in topological insulators and semimetals / Björn Sbierski." Berlin : Freie Universität Berlin, 2016. http://d-nb.info/1102197114/34.
Full textLau, Alexander. "Symmetry-enriched topological states of matter in insulators and semimetals." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-233930.
Full textEkahana, Sandy Adhitia. "Investigation of topological nodal semimetals through angle-resolved photoemission spectroscopy." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:afed6156-7aa2-4ba9-afd1-af53d775494f.
Full textDu, Xu. "Magnetotransport and tunneling study of the semimetals bismuth and graphite." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0008357.
Full textOumous, Hassan. "Fabrication and characterisation of CuInSeâ†2 films on large subtrates for solar cell devices." Thesis, University of Newcastle Upon Tyne, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329544.
Full textLee, Kiyoung. "Spin dependent transport in semiconductor and semimetal materials." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610139.
Full textOsterhoudt, Gavin Barnes. "Spectroscopy of Topological Materials:." Thesis, Boston College, 2020. http://hdl.handle.net/2345/bc-ir:109002.
Full textSince their first experimental realizations in the 2000s, bulk electronic topological materials have been one of the most actively studied areas of condensed matter physics. Among the more recently discovered classes of topological materials are the Weyl semimetals whose low energy excitations behave like massless, relativistic particles with well-defined chirality. These material systems display exotic behavior such as surface Fermi arc states, and the chiral anomaly in which parallel magnetic and electric fields lead to an imbalance of left- and right-handed particles. Much of the research into these materials has focused on the electronic properties, but relatively little has been directed towards understanding the vibrational properties of these systems, or of the interplay between the electronic and vibrational degrees of freedom. Further, the technological potential of these materials is still underdeveloped, with the search for physical properties enhanced by the topological nature of these materials being sought after. In this dissertation we address both of these issues. In Chapters III and IV we present temperature dependent Raman investigations of the the Weyl semimetals WP2, NbAs, and TaAs. Measurements of the optical phonon linewidths are used to identify the available phonon decay paths, with ab-initio calculations and group theory used to aid the interpretation of these results. We find that some phonons display linewidths indicative of dominant decay into electron-hole pairs near the Fermi surface, rather than decay into acoustic phonons. In light of these results we discuss the role of phonon-electron coupling in the transport properties of these Weyl semimetals. In Chapter V, we discuss the construction of our "PVIC" setup for the measurement of nonlinear photocurrents. We discuss the experimental capabilities that the system was designed to possess, the operating principles behind key components of the system, and give examples of the operating procedures for using the setup. The penultimate chapter, Chapter VI, presents the results of photocurrent measurements using this setup on the Weyl semimetal TaAs. Through careful analysis of the photocurrent polarization dependence, we identify a colossal bulk photovoltaic effect in this material which exceeds the response displayed by previously studied materials by an order of magnitude. Calculations of the second-order optical conductivity tensor show that this result is consistent with the divergent Berry connection of the Weyl nodes in TaAs. In addition to these topics, Chapter II addresses the results of Raman measurements on thin film heterostructures of the topological insulator Bi2Se3 and the magnetic semiconductor EuS. By investigating the paramagnetic Raman signal in films with different compositions of EuS and Bi2Se3 we provide indirect evidence of charge transfer between the two layers. We also track the evolution of phonon energies with varying film thicknesses on multiple substrates which provides insight into the interfacial strain between layers. We conclude the dissertation in Chapter VII with a summary of the main results from each preceding chapter, and give suggestions for future experiments that further investigate these topics
Thesis (PhD) — Boston College, 2020
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Physics
Hirschberger, Maximilian Anton. "Quasiparticle Excitations with Berry Curvature in Insulating Magnets and Weyl Semimetals." Thesis, Princeton University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10286472.
Full textThe concept of the geometric Berry phase of the quantum mechanical wave function has led to a better theoretical understanding of natural phenomena in all fields of fundamental physics research. In condensed matter physics, the impact of this theoretical discovery has been particularly profound: The quantum Hall effect, the anomalous Hall effect, the quantum spin Hall effect, magnetic skyrmions, topological insulators, and topological semimetals are but a few subfields that have witnessed rapid developments over the three decades since Michael Berry's landmark paper. In this thesis, I will present and discuss the results of three experiments where Berry's phase leads to qualitatively new transport behavior of electrons or magnetic spin excitations in solids.
We introduce the theoretical framework that leads to the prediction of a thermal Hall effect of magnons in Cu(1,3-bdc), a simple two-dimensional layered ferromagnet on a Kagomé net of spin S = 1/2 copper atoms. Combining our experimental results measured down to very low temperatures T = 0.3 K with published data from inelastic neutron scattering, we report a quantitative comparison with the theory. This confirms the expected net Berry curvature of the magnon band dispersion in this material.
Secondly, we have studied the thermal Hall effect in the frustrated pyrochlore magnet Tb2Ti2O7, where the thermal Hall effect is large in the absence of long-range magnetic order. We establish the magnetic nature of the thermal Hall effect in Tb2Ti2O7, introducing this material as the first example of a paramagnet with non-trivial low-lying spin excitations. Comparing our results to other materials with zero thermal Hall effect such as the classical spin ice Dy2Ti 2O7 and the non-magnetic analogue Y2Ti2O 7, we carefully discuss the experimental limitations of our setup and rule out spurious background signals.
The third and final chapter of this thesis is dedicated to electrical transport and thermopower experiments on the half-Heusler material GdPtBi. A careful doping study of the negative longitudinal magnetoresistance (LMR) establishes GdPtBi as a new material platform to study the physical properties of a simple Weyl metal with only two Weyl points (for magnetic field along the crystallographic 〈111〉 direction). The negative LMR is associated with the theory of the chiral anomaly in solids, and a direct consequence of the nonzero Berry curvature of the energy band structure of a Weyl semimetal. We compare our results to detailed calculations of the electronic band structure. Moving beyond the negative LMR, we report for the first time the effect of the chiral anomaly on the longitudinal thermopower in a Weyl semimetal.
de, Coster George. "Effective Soft-Mode Theory of Strongly Interacting Fermions in Dirac Semimetals." Thesis, University of Oregon, 2019. http://hdl.handle.net/1794/24235.
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Haubold, Erik [Verfasser], Bernd [Gutachter] Büchner, and Oliver [Gutachter] Rader. "Electronic structure of topological semimetals / Erik Haubold ; Gutachter: Bernd Büchner, Oliver Rader." Dresden : Technische Universität Dresden, 2019. http://d-nb.info/1226944779/34.
Full textNilforoushan, Niloufar. "Out-of-equilibrium electron dynamics of Dirac semimetals and strongly correlated materials." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS573/document.
Full textQuantum materials is a new term in condensed matter physics that unifies all materials in which strong electronic correlation governs physical properties of the system (e.g. Mott insulators) and materials whose electronic properties are determined by the geometry of the electronic wave function (e.g. Dirac materials). These materials show emergent properties– that is, properties that only appear by intricate interactions among many degrees of freedom, such as charge, spin and orbital, giving rise to topological properties of electrons. The study of these interactions and competitions between the relevant degrees of freedom demands applying ultrafast pump-probe techniques. Particularly, femtosecond laser pulses act only on the electrons and set them to an out-of-equilibrium state inexplicable by the Fermi-Dirac distribution. The ensuing dynamics involves various processes and the rate at which the relaxation occurs is related to the coupling constants. Moreover, in time-resolved pump-probe techniques light can act as an additional external parameter to change of the phase diagram – different from thermodynamic parameters. It gives us the opportunity of stabilizing new states inaccessible by quasi-adiabatic thermal pathways or eventually manipulating the physical properties of the systems.In this thesis, we performed different experiments in order to study the equilibrium and out-of-equilibrium properties of two correlated compounds: BaCo₁₋ₓNiₓS₂ and (V₁₋ₓMₓ)₂O₃.The first part of the project was mainly devoted to the study of BaNiS₂ that is the metallic precursor of the Mott transition in BaCo₁₋ₓNiₓS₂. By applying ARPES, we studied the electronic band structure of BaNiS₂ in its entire Brillouin zone. These results combined with some theoretical calculations give evidence of a novel correlation-induced and two-dimensional Dirac cone with d-orbital character. The band crossing is protected by the specific symmetries of the crystal structure. We also investigated the electronic band structure of the Mott insulator BaCoS₂ in its magnetic and nonmagnetic phases.In the second part, we studied the out-of-equilibrium electron dynamics of BaNiS₂ and (V₁₋ₓMx)₂O₃. By means of tr-ARPES and tr-reflectivity measurements, we observed an ultrafast and non-thermal renormalization of the Dirac cone in BaNiS₂ . This phenomenon is purely provoked by the electronic excitation and is stabilized by the interplay between the electrons and phonons. Moreover, by applying various pump-probe techniques (XFEL-based tr-XRD and tr-Reflectivity) we also explored the out-of-equilibrium phases of the prototype Mott-Hubbard material (V₁₋ₓMx)₂O₃ in different parts of its phase diagram. Our results show a transient non-thermal phase developing immediately after ultrafast photoexcitation and lasting few picoseconds in both metallic and insulating phases. This transient phase is followed by a structural distortion that corresponds to a lattice hardening and is marked by a “blue shift” of the A₁g phonon mode. These results underline the importance of the orbital filling as well as the strong effect of the selective electron-lattice coupling in the strongly correlated materials
Khalaf, Eslam [Verfasser], and Walter [Akademischer Betreuer] Metzner. "Mesoscopic phenomena in topological insulators, superconductors and semimetals / Eslam Khalaf ; Betreuer: Walter Metzner." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2017. http://d-nb.info/1137510145/34.
Full textSchilling, Micha Benjamin [Verfasser], and Martin [Akademischer Betreuer] Dressel. "Optical studies on Dirac and Weyl semimetals / Micha Benjamin Schilling ; Betreuer: Martin Dressel." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2018. http://d-nb.info/1173163816/34.
Full textVidal, Jordina. "Modelling for transient optically induced metal-insulator transitions in narrow-gap semiconductors and semimetals." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/17361.
Full textCheng, Tak Keung. "The excitation andn dynamics of coherent lattice vibrations in semimetals and narrow-gap semiconductors." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12008.
Full textGuggenheim, Charles Moses [Verfasser], Martin [Gutachter] Zirnbauer, and Alexander [Gutachter] Altland. "Weyl semimetals: Euler structures and disorder / Charles Moses Guggenheim ; Gutachter: Martin Zirnbauer, Alexander Altland." Köln : Universitäts- und Stadtbibliothek Köln, 2020. http://d-nb.info/1219652415/34.
Full textRancati, Andrea. "Ab initio simulations of topological phase transitions in Dirac semimetal Cd3As2 doped with Zn and Mn impurities." Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-80767.
Full textTopp, Andreas [Verfasser], and Christian R. [Akademischer Betreuer] Ast. "Probing the electronic structure of new 3D Dirac semimetals / Andreas Topp ; Betreuer: Christian R. Ast." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2019. http://d-nb.info/1193492076/34.
Full textNeubauer, David [Verfasser], and Martin [Akademischer Betreuer] Dressel. "Optical and magneto-optical investigations on 3D Dirac- and Weyl-semimetals / David Neubauer ; Betreuer: Martin Dressel." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2017. http://d-nb.info/1136319506/34.
Full textNaumann, Marcel [Verfasser], Elena [Akademischer Betreuer] Hassinger, Elena [Gutachter] Hassinger, and Clemens [Gutachter] Laubschat. "The longitudinal magnetoresistance of Weyl semimetals / Marcel Naumann ; Gutachter: Elena Hassinger, Clemens Laubschat ; Betreuer: Elena Hassinger." München : Universitätsbibliothek der TU München, 2019. http://d-nb.info/1190818817/34.
Full textYang, Hung-Yu. "Novel Electromagnetic Responses in Topological Semimetals: Case Studies of Rare-Earth Monopnictides and RAlX Material Family." Thesis, Boston College, 2021. http://hdl.handle.net/2345/bc-ir:109188.
Full textSince the idea of topology was realized in real materials, the hunt is on for new candidates of topological semimetals with novel electromagnetic responses. For example, topological states can be highly conductive due to a topological protection, which can be destroyed in a magnetic field and lead to an extremely high magnetoresistance. In Weyl semimetals, a transverse current that would usually require a magnetic field to emerge, can be generated by intrinsic Berry curvature without a magnetic field -- the celebrated anomalous Hall effect. In this dissertation, both phenomena mentioned above are studied in rare-earth monopnictides and RAlX material family (R=rare-earths, X=Ge/Si), respectively. The monopnictides are ideal for the study of extreme magnetoresistance because of their topological transitions and abundant magnetic phases. In LaAs, we untied the connection between topological states and the extreme magnetoresistance, the origin of which is clarified. In HoBi, we found an unusual onset of extreme magnetoresistance controlled by a magnetic phase dome. On the other hand, RAlX material family is a new class of Weyl semimetals breaking both inversion and time-reversal symmetries. In particular, in PrAlGeₓSi₁₋ₓ (x=0-1), we unveiled the first transition from intrinsic to extrinsic anomalous Hall effect in ferromagnetic Weyl semimetals, and the role of topology is discussed. In CeAlSi, we found that the Fermi level can be tuned as close as 1 meV away from the Weyl nodes; moreover, a novel anomalous Hall response appears only when the Fermi level is tuned to be near the Weyl nodes. Thus, we established a new transport response solely induced by Weyl nodes
Thesis (PhD) — Boston College, 2021
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Physics
Theóphilo, Carolina Yume Sawamura. "Análise de elementos potencialmente tóxicos em material biológico da Ilha da Trindade, Brasil." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/21/21137/tde-26112014-161310/.
Full textThe Trindade Island is located approximately 1150 km from the coast of Vitória-ES, is one of Brazilian oceanic islands and is under the control of the Brazilian Navy. At the time the occupation began the island suffered some anthropogenic influences, such as the removal of trees and the animals introduction (pigs and goats). Metals originating from the shore or from ships passing through the region, are highlighting among the environmental contaminants that can change the ecosystem of the island. So the aim of this study was to quantify Al, As, Cd, Cu, Fe, Mn, Ni, Pb, Se, Zn and Hg in three hundred samples of muscle of two species of crab and liver and muscle of fish (two species) and seabirds (three species). The relationships between biological parameters (sex, length, weight), differences between tissues and between sampling periods were checked. The concentration of Fe, G. lagostoma (crab), and the Zn, in G. grapsus (crab), showed higher concentrations in the warmer months, in which biological activity is greater, being a possible cause for higher concentrations. Different from crabs, the species M. niger (fish) presented higher concentrations (Al in the muscle and Fe and Zn in the liver) in the colder months, concentrations in fish involve many factors besides the seasonality. For both species of fish concentrations of Fe and Zn were higher in the liver as well as for P. arminjoniana (seabird) concentrations of Cu, Fe and Zn were higher in the liver, like was expected, because the liver is a tissue with a great capacity to accumulate pollutants. Some elements showed correlations with the weight and/or length, but all very low, with the exception of Zn in G. grapsus. All Hg analyzes performed were below the method quantification limit (17.7 µg kg-1). The metals and semimetals showed similar results to studies conducted in other regions.
Medeiros, Fabio Henrique [UNESP]. "Caracterização da deposição atmosférica e aporte de espécies químicas no principal corpo aquático da cidade de São José do Rio Preto, SP." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/97770.
Full textFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
A atmosfera tem grande importância no transporte e distribuição de elementos oriundos de atividades naturais ou antrópicas, sobre a superfície terrestre, sendo a deposição atmosférica o principal processo de ciclagem dos compostos químicos entre os compartimentos ambientais. A cidade de São José do Rio Preto (SJRP) possui um pequeno parque industrial, conta com a presença de duas rodovias de grande tráfego, a rodovia Washington Luís (SP-310) e a rodovia Transbrasiliana (BR-153), e em termos agrícolas a região é responsável por 12% da produção de etanol do estado, e destacando-se também, em menor quantidade, o cultivo da laranja e de pastagens. Neste contexto o objetivo deste trabalho foi a caracterização de espécies químicas na deposição atmosférica total (DT) e deposição atmosférica apenas úmida (DU) da cidade de SJRP visando avaliar a contribuição da mesma como fonte destes compostos para o rio Preto. Um total de 103 amostras de DT e 96 de DU foram coletadas para o período de março de 2009 a setembro de 2010. A amostragem, preservação e quantificação de Al, Sb, As, Ba, Cd, Cu, Pb, Cr, Ni, Zn, K+, NH4 +, PO4 3-, NO3 -, SO4 2-, pH, C.E. e TOC (Carbono Orgânico Total) foram realizadas seguindo recomendações de métodos oficiais. Os resultados obtidos e expressos como média ponderada pelo volume (MPV) para as amostras de DT e de DU foram maiores no período de safra da cana-de-açúcar para Ni (0,53 e 0,44 µg L-1), Al (63 e 28 µg L-1), Pb (0,88 e 0,66 µg L-1), Ba (4,67 e 3,20 µg L-1), Zn (9,21 e 5,50 µg L-1), K+ (0,68 e 0,17 mg L-1), NH4 + (1,31 e 0,38 mg L-1), SO4 2- (5,99 e 4,70 mg L-1), PO4 3- (3,08 e 0,48 mg L-1) e NO3 - (0,94 e 0,40 mg L-1). Destaca-se para o Cr a maior MPV nas amostras de DT também no período de safra da cana-de-açúcar (0,33 µg L-1), já para as amostras de DU o valor de MPV para ambos os períodos...
The atmosphere plays a very important role in transport and distribution of elements from natural and anthropogenic activities on the earth. The atmospheric deposition is the main process through which chemical compounds present in the atmosphere can be reintroduced to other environmental compartments. The city of São José do Rio Preto (SJRP) has a small industrial park, and two highways, Washington Luís (SP-310) and Transbrasiliana (Br-153), and in agricultural terms it is responsible for 12% of the ethanol production in the state of São Paulo, and in smaller proportion stand the orange crop and pasture. In this context the objective of this work was the characterization of the chemical species in the bulk (BD) and wet only (WD) deposition of SJRP city to evaluate the contribution of deposition as a diffuse source of compounds for the Preto river. A total of 103 bulk and 96 wet-only samples were collected for the period of March 2009 to September 2010. The sampling, preservation and quantification of Al, Sb, As, Ba, Cd, Cu, Pb, Cr, Ni, K e Zn, NH4 +, PO4 3-, NO3 -, SO4 2-, pH, E.C. and TOC were performed in accordance with official methods recommendations. The results obtained and expressed as volume-weighted mean concentration (VWM) was higher for the sugar cane harvest period for BD and WD for Ni (0.53 and 0.44 µg L-1), Al (63 and 28 µg L-1), Pb (0.88 and 0.66 µg L-1), Ba (4.67 and 3.20 µg L-1), Zn (9.21 and 5.50 µg L-1), K+ (0.68 and 0.17 mg L-1), NH4 + (1.31 and 0.38 mg L-1), SO4 2- (5.99 and 4.70 mg L-1), PO4 3- (3.08 and 0.48 mg L-1) and NO3 - (0.94 and 0.40 mg L-1). The highest Cr VWM (0.33 µg L-1) in the bulk samples was also observed for the sugar cane harvest period, but with regard to the WOD samples the VWM for both periods was the same (0.13 µg L-1). For Cu, TOC and NPOC the highest VWM was observed for the sugar cane harvest period, for the BD samples... (Complete abstract click electronic access below)
Huang, Minjuan. "Risk assessments of human exposure to metal(loid)s via urban dust and airborne particles in Guangzhou, South China." HKBU Institutional Repository, 2013. http://repository.hkbu.edu.hk/etd_ra/1494.
Full textGállová, Eva. "Stanovení polokovových prvků v potravinách." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-216751.
Full textNaozuka, Juliana. "Especiação química elementar em castanha-do-pará, coco e cupuaçu." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-19122008-140514/.
Full textIn this work, studies were done for the fractionation and speciation of Cu, Fe, Mn, Se and Zn in Brazil-nut (Bertholletia excelsa H.B.K.), cupuassu (Theobroma grandiflorum) seeds and coconut (Cocos nucifera L.) pulp. The sequential solid-liquid extraction combined with GF AAS was used to fractionation and determination of elements associated to proteins fractions. The determined protein concentrations in extractants of Brazil-nut (6 a 76 mg g-1) are higher than those observed for extractants of cupuassu seeds (2 a 27 mg g-1) and coconut pulp (1 a 12 mg g-1). The preliminary relationship of Cu, Fe, Mn, Se and Zn associated to different proteins groups was observed, indicating a possible interation of these elements with albumins, globulins, prolamins and glutelins. The on-line SEC-UV and off-line SEC-UV GFAAS hyphenation was applied with sucess for the identification of Cu, Fe, Mn, Se and Zn species in the water, NaCl and NaOH extractants of Brazil-nut, cupuassu seeds and coconut pulp. In general, the interest elements were found associated to species of molecular weights lower than 13 kDa for water and NaCl extractants and 28 kDa for NaOH extractants. The combination of the informations of this hyphenation with MALDI-TOF mass spectra of the Brazil-nut gave confirmation of the association of the Cu, Fe, Mn, Se and Zn with two water-soluble species of 6 kDa (Fe, Mn and Zn) and 11 kDa (Cu, Mn and Se).
Behrends, Jan [Verfasser], Jens H. [Akademischer Betreuer] Bardarson, Jens H. [Gutachter] Bardarson, Roderich [Gutachter] Moessner, and Carsten [Gutachter] Timm. "Transport and Quantum Anomalies in Topological Semimetals / Jan Behrends ; Gutachter: Jens H. Bardarson, Roderich Moessner, Carsten Timm ; Betreuer: Jens H. Bardarson." Dresden : Technische Universität Dresden, 2019. http://d-nb.info/1226897495/34.
Full textRauch, Tomáš Verfasser], Ingrid [Akademischer Betreuer] [Mertig, Steffen [Akademischer Betreuer] Trimper, and Markus [Akademischer Betreuer] Donath. "Topological insulators and semimetals : theory for bulk and surface electronic properties : [kumulative Dissertation] / Tomáš Rauch ; Ingrid Mertig, Steffen Trimper, Markus Donath." Halle, 2016. http://d-nb.info/1116952483/34.
Full textMedeiros, Fabio Henrique. "Caracterização da deposição atmosférica e aporte de espécies químicas no principal corpo aquático da cidade de São José do Rio Preto, SP /." São José do Rio Preto : [s.n.], 2011. http://hdl.handle.net/11449/97770.
Full textBanca: Pedro Sergio Fadini
Banca: Mauricio Boscolo
Resumo: A atmosfera tem grande importância no transporte e distribuição de elementos oriundos de atividades naturais ou antrópicas, sobre a superfície terrestre, sendo a deposição atmosférica o principal processo de ciclagem dos compostos químicos entre os compartimentos ambientais. A cidade de São José do Rio Preto (SJRP) possui um pequeno parque industrial, conta com a presença de duas rodovias de grande tráfego, a rodovia Washington Luís (SP-310) e a rodovia Transbrasiliana (BR-153), e em termos agrícolas a região é responsável por 12% da produção de etanol do estado, e destacando-se também, em menor quantidade, o cultivo da laranja e de pastagens. Neste contexto o objetivo deste trabalho foi a caracterização de espécies químicas na deposição atmosférica total (DT) e deposição atmosférica apenas úmida (DU) da cidade de SJRP visando avaliar a contribuição da mesma como fonte destes compostos para o rio Preto. Um total de 103 amostras de DT e 96 de DU foram coletadas para o período de março de 2009 a setembro de 2010. A amostragem, preservação e quantificação de Al, Sb, As, Ba, Cd, Cu, Pb, Cr, Ni, Zn, K+, NH4 +, PO4 3-, NO3 -, SO4 2-, pH, C.E. e TOC (Carbono Orgânico Total) foram realizadas seguindo recomendações de métodos oficiais. Os resultados obtidos e expressos como média ponderada pelo volume (MPV) para as amostras de DT e de DU foram maiores no período de safra da cana-de-açúcar para Ni (0,53 e 0,44 µg L-1), Al (63 e 28 µg L-1), Pb (0,88 e 0,66 µg L-1), Ba (4,67 e 3,20 µg L-1), Zn (9,21 e 5,50 µg L-1), K+ (0,68 e 0,17 mg L-1), NH4 + (1,31 e 0,38 mg L-1), SO4 2- (5,99 e 4,70 mg L-1), PO4 3- (3,08 e 0,48 mg L-1) e NO3 - (0,94 e 0,40 mg L-1). Destaca-se para o Cr a maior MPV nas amostras de DT também no período de safra da cana-de-açúcar (0,33 µg L-1), já para as amostras de DU o valor de MPV para ambos os períodos... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The atmosphere plays a very important role in transport and distribution of elements from natural and anthropogenic activities on the earth. The atmospheric deposition is the main process through which chemical compounds present in the atmosphere can be reintroduced to other environmental compartments. The city of São José do Rio Preto (SJRP) has a small industrial park, and two highways, Washington Luís (SP-310) and Transbrasiliana (Br-153), and in agricultural terms it is responsible for 12% of the ethanol production in the state of São Paulo, and in smaller proportion stand the orange crop and pasture. In this context the objective of this work was the characterization of the chemical species in the bulk (BD) and wet only (WD) deposition of SJRP city to evaluate the contribution of deposition as a diffuse source of compounds for the Preto river. A total of 103 bulk and 96 wet-only samples were collected for the period of March 2009 to September 2010. The sampling, preservation and quantification of Al, Sb, As, Ba, Cd, Cu, Pb, Cr, Ni, K e Zn, NH4 +, PO4 3-, NO3 -, SO4 2-, pH, E.C. and TOC were performed in accordance with official methods recommendations. The results obtained and expressed as volume-weighted mean concentration (VWM) was higher for the sugar cane harvest period for BD and WD for Ni (0.53 and 0.44 µg L-1), Al (63 and 28 µg L-1), Pb (0.88 and 0.66 µg L-1), Ba (4.67 and 3.20 µg L-1), Zn (9.21 and 5.50 µg L-1), K+ (0.68 and 0.17 mg L-1), NH4 + (1.31 and 0.38 mg L-1), SO4 2- (5.99 and 4.70 mg L-1), PO4 3- (3.08 and 0.48 mg L-1) and NO3 - (0.94 and 0.40 mg L-1). The highest Cr VWM (0.33 µg L-1) in the bulk samples was also observed for the sugar cane harvest period, but with regard to the WOD samples the VWM for both periods was the same (0.13 µg L-1). For Cu, TOC and NPOC the highest VWM was observed for the sugar cane harvest period, for the BD samples... (Complete abstract click electronic access below)
Mestre
Möckel, Sebastian [Verfasser], Martin [Gutachter] Ammon, Johanna [Gutachter] Erdmenger, and Dias Oscar [Gutachter] Campos. "Numerical studies of higher-dimensional localized black holes and holographic Weyl semimetals / Sebastian Möckel ; Gutachter: Martin Ammon, Johanna Erdmenger, Oscar Campos Dias." Jena : Friedrich-Schiller-Universität Jena, 2018. http://d-nb.info/117220683X/34.
Full textYang, Shuo-Ying [Verfasser], Stuart S. P. [Gutachter] Parkin, Ingrid [Gutachter] Mertig, and Vitto Zheng [Gutachter] Han. "In search of extraordinary Hall effects in topological semimetals / Shuo-Ying Yang ; Gutachter: Stuart S. P. Parkin, Ingrid Mertig, Vitto Zheng Han." Halle (Saale) : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2020. http://d-nb.info/1222513757/34.
Full textLau, Alexander [Verfasser], Jeroen van den [Akademischer Betreuer] Brink, Jeroen van den [Gutachter] Brink, and Carmine [Gutachter] Ortix. "Symmetry-enriched topological states of matter in insulators and semimetals / Alexander Lau ; Gutachter: Jeroen van den Brink, Carmine Ortix ; Betreuer: Jeroen van den Brink." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://d-nb.info/1154680487/34.
Full textWatzman, Sarah June. "Thermal Energy Conversion Utilizing Magnetization Dynamics and Two-Carrier Effects." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523621461827864.
Full textNoky, Jonathan [Verfasser], Claudia [Gutachter] Felser, Claudia [Akademischer Betreuer] Felser, Jeroen van den [Gutachter] Brink, and Jürgen [Gutachter] Kübler. "Anomalous electric, thermal, and thermoelectric transport in magnetic topological metals and semimetals / Jonathan Noky ; Gutachter: Claudia Felser, Jeroen van den Brink, Jürgen Kübler ; Betreuer: Claudia Felser." Dresden : Technische Universität Dresden, 2021. http://d-nb.info/123917702X/34.
Full textRIBEIRO, ANDREZA P. "Determinacao de metais pesados e outros elementos de interesse em sedimentos lacustres da Estacao de Tratamento de Esgoto de Barueri, Sao Paulo, por ativacao neutronica." reponame:Repositório Institucional do IPEN, 2002. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11026.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:00/00546-3
Kirby, Jason K., and n/a. "Trace metal and metalloid accumulation, distribution, and, speciation in Lake Macquarie, N.S.W., Australia." University of Canberra. Resource, Environmental & Heritage Sciences, 2005. http://erl.canberra.edu.au./public/adt-AUC20051129.124508.
Full textFAUSTINO, MAINARA G. "Desenvolvimento e validação de metodologia para determinação de metais em amostras de água por espectrometria de emissão óptica com plasma de argônio (ICP-OES)." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26081.
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Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
MARQUES, JOYCE R. "Otimização e validação de metodologia analítica para determinação de metais e semimetais em efluentes líquidos por espectrometria de emissão óptica com plasma de argônio (ICP-OES)." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26080.
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Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
Louvet, Thibaud. "Phases relativistes en matière condensée." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN025/document.
Full textThis thesis adresses the study of crystals called relativistic semi-metals, in which electrons behave like massless relativistic particles.The first historical example of such a material is graphene.In this planar arrangement of carbon atoms, electronic valence and conduction bands touch at two distincts points in the reciprocal lattice. Thus, graphene is a zero-gap semiconductor, a semi-metal.The dynamics of electrons close to the Fermi level is relativistic, described by a Dirac equation, although their velocity is a hunder times lower than the velocity of light in vacuum. Analogous semi-metallic phases have recently been identified: 3D Weyl and Dirac semimetals, as well as more exotic phases described by crossings with more than two bands. This variety of relativistic materials raises the question of their common properties. A first part of this thesis presents work related to the study of the stability of these phases, i.e. of the electronic band crossing. We have investigated this stability first by relating it to topological properties, then by evaluating the effect of disorder, such as the presence of impurities in the material. In the second part, we focus on the manifestation of the relativistic nature of these electrons in transport. In a first study, we examine the condition of existence of a finite conductivity exactly at the band crossing, due to the contribution of evanescent states. A second study concerns the anomalous transport under a magnetic field in Weyl semi-metals, as a manifestation of the chiral anomaly, a unique property of massless relativistic fermions
Radmanesh, Seyed Mohammad Ali. "Ultra-low Temperature Properties of Correlated Materials." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2511.
Full textMizobata, William Nobuhiro. "Interação entre impurezas enterradas em um semimetal de Weyl : caso magnético /." Ilha Solteira, 2019. http://hdl.handle.net/11449/181343.
Full textResumo: Investigamos teoricamente um sistema composto por duas impurezas afastadas e enterradas em um semimetal de Weyl. Analisamos a densidade de estados local para duas situações: com simetrias de reversão temporal e inversão preservadas e; simetria de reversão temporal quebrada e inversão preservada. Na situação em que as duas simetrias são preservadas, o Hamiltoniano descreve um semimetal de Dirac. Sendo assim, verificamos a densidade de estados local em dois pontos diferentes do semimetal de Dirac e os orbitais moleculares formado pelas impurezas. É possível observar que em alguns pontos, a densidade de estados total, que pode ser obtido experimentalmente via espectroscopia de varredura por tunelamento, há a presença de apenas dois picos, enquanto que em outro ponto há a presença de quatro picos. Sendo assim, a presença de dois picos nos leva a crer que não há interação entre as impurezas, entretanto, em outro ponto que contém quatro picos em sua densidade de estados, mostra que há interação entre as impurezas. Analisamos os orbitais moleculares realizando uma topografa espacial da densidade de estados e é possível observar estados ligante e antiligante entre as impurezas com orbitais s. A segunda situação, com a quebra de simetria de reversão temporal e simetria de inversão preservada, temos um semimetal de Weyl com as bandas de energias separadas no espaço dos momentos e com energias degeneradas. Verificamos na densidade de estados local, uma magnetização das impurezas devido ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: We investigate theoretically the setup composed by two distant impurities and burried in Weyl semimetal. We analyze a local density of states for two situations: with time reversal symmetry and inversion symmetry preserved and; time reversal symmetry broken and inversion symmetry preserved. In the situation that the two symmetries are preserved, the Hamiltonian describes a Dirac semimetal. Therefore, we verified the local density of states in two different points of Dirac semimetal and the molecular orbital formed by the impurities. It is possible to observe that in some points, the total density of states, which can be obtained experimentally via scanning tunneling microscope, there is the presence of just two peaks, while that in another point there is the presence of four peaks. Therefore, the presence of two peaks leads us to belive that there is no interaction between impurities, however, in the another point that contain four peaks in the density of states, show that there is interaction between the impurities. We analyze the molecular orbital realizing a spacial topography of density of states and it is possible to observe bonding and antibonding states between impurities with s orbital. The second situation, with the time reversal symmetry broken and inversion symmetry preserved, we have a Weyl semimetal with separated energy bands in momentum space and degenerate energy. We verified in the local density of states, a magnetization of the impurities due to the time rev... (Complete abstract click electronic access below)
Mestre
Báring, Luís Augusto Gomes 1983. "Supercondutividade em semimetais e isolantes topológicos." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277009.
Full textTese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: No presente trabalho estudamos os semimetais bismuto Bi, antimônio Sb e Bi1-xSbx, materiais com propriedades topologicamente não triviais. Observamos a ocorrência de supercondutividade intrínseca em bismuto com TC »= 8:5K. Construímos, a partir dos dados de magnetização e resistência, o diagrama de fase do campo crítico H versus a temperatura T. Esse diagrama de fase, pode ser ajustado segundo modelos da literatura válidos para supercondutividade granular. Detectamos, no bismuto, o aumento da corrente Josephson e acoplamento intergranular no limite quântico devidos à quantização de Landau. Isso se manifesta como uma supercondutividade reentrante. Foi também encontrada transição tipo metal-isolante induzida por campo magnético em todos os materiais estudados. O diagrama de fase H versus T mostra uma extraordinária semelhança entre os três materiais. A amostra Bi1-xSbx, com x = 0:052, revelou a ocorrência de transição semimetal-isolante topológico já em campo magnético zero. Fizemos uma comparação com resultados anteriores da literatura, analisando a dependência da temperatura em que ocorre essa transição em relação à concentração de antimônio x e ao campo magnético B e demonstramos a similaridade entre eles. Observamos, também, supercondutividade nos semimetais bismuto, antimônio e no Bi1-xSbx, induzida por dopagem com os metais ouro e índio, e mostramos que a supercondutividade está associada à interface entre os metais e os semimetais. Finalmente, encontramos a indução de supercondutividade mediante a aplicação de campo magnético em bismuto, consistente com a ocorrência de férmions de Majorana na interface entre esse material e a tinta prata usada para os contatos. Tal observação pode ser devida, também, à ocorrência de um estado supercondutor fora do equilíbrio.
Abstract: In this work we studied the semimetals bismuth Bi, antimony Sb and Bi1-xSbx, all of them with non-trivial topologic properties. We observed an intrinsic superconductivity in bismuth, with TC »= 8:5 K. The phasediagram of the critical field H versus the temperature T, based upon the magnetization and resistance data, may be well fitted according to theoretical models valid for granular superconductivity. We also detected, in bismuth, the increase of the Josephson current and interganular coupling in the quantum limit due to Landau quantization. This manifests itself as a reentrant superconducting state. Our results revealed a metal-insulator transition triggered by magnetic field, for all the studied materials. The phase diagram H ¡T shows a striking similarity between them. The sample Bi1-xSbx with x = 0:052 demonstrated a semimetal-insulator transition even at zero field. We compared our results with previous results of other groups and analyzed the temperature dependence of the transition as a function of the antimony amount x and the magnetic field B and demonstrated their similarity. We also observed supeerconductivity in the semimetals bismuth, antimony and Bi1-xSbx, triggered by doping with the metals gold and indium, and showed that the superconductivity is associated to the interface between the metals and the semimetals. Finally, we found the superconductivity induced by the aplication of magnetic field in bismuth, consistent with the Majorana fermions present in the interface between this material and the silver paste contacts. This may also be related to a non-equilibrium superconduting state.
Doutorado
Física
Doutor em Ciências