Thematische Bibliographien / Dirac and Weyl fermions

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Auswahl der wissenschaftlichen Literatur zum Thema „Dirac and Weyl fermions“

Autor: Grafiati

Veröffentlicht am 25. Mai 2024

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Zeitschriftenartikel zum Thema "Dirac and Weyl fermions"

Ma, Tian-Chi, Jing-Nan Hu, Yuan Chen, Lei Shao, Xian-Ru Hu und Jian-Bo Deng. „Coexistence of type-II and type-IV Dirac fermions in SrAgBi“. Modern Physics Letters B 35, Nr. 11 (09.02.2021): 2150181. http://dx.doi.org/10.1142/s0217984921501815.

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Relativistic massless Weyl and Dirac fermions have isotropic and linear dispersion relations to maintain Poincaré symmetry, which is the most basic symmetry in high-energy physics. The situation in condensed matter physics is less constrained; only certain subgroups of Poincaré symmetry — the 230 space groups that exist in 3D lattices — need be respected. Then, the free fermionic excitations that have no high-energy analogues could exist in solid state systems. Here, We discovered a type of nonlinear Dirac fermion without high-energy analogue in SrAgBi and named it type-IV Dirac fermion. The type-IV Dirac fermion has a nonlinear dispersion relationship and is similar to the type-II Dirac fermion, which has electron pocket and hole pocket. The effective model for the type-IV Dirac fermion is also found. It is worth pointing out that there is a type-II Dirac fermion near this new Dirac fermion. So we used two models to describe the coexistence of these two Dirac fermions. Topological surface states of these two Dirac points are also calculated. We envision that our findings will stimulate researchers to study novel physics of type-IV Dirac fermions, as well as the interplay of type-II and type-IV Dirac fermions.

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Pal, Palash B. „Dirac, Majorana, and Weyl fermions“. American Journal of Physics 79, Nr. 5 (Mai 2011): 485–98. http://dx.doi.org/10.1119/1.3549729.

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ALONSO, J. L., J. L. CORTÉS und E. RIVAS. „WEYL FERMION FUNCTIONAL INTEGRAL AND TWO-DIMENSIONAL GAUGE THEORIES“. International Journal of Modern Physics A 05, Nr. 14 (20.07.1990): 2839–51. http://dx.doi.org/10.1142/s0217751x90001331.

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In the path integral approach we introduce a general regularization scheme for a Weyl fermionic measure. This allows us to study the functional integral formulation of a two-dimensional U(1) gauge theory with an arbitrary content of left-handed and right-handed fermions. A particular result is that, in contrast with a regularization of the fermionic measure based on a unique Dirac operator, by taking the Dirac fermionic measure as a product of two independent Weyl fermionic measures a consistent and unitary result can be obtained for the Chiral Schwinger Model (CSM) as a byproduct of the arbitrariness in the definition of the fermionic measure.

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Huang, Silu, Jisun Kim, W. A. Shelton, E. W. Plummer und Rongying Jin. „Nontrivial Berry phase in magnetic BaMnSb2 semimetal“. Proceedings of the National Academy of Sciences 114, Nr. 24 (24.05.2017): 6256–61. http://dx.doi.org/10.1073/pnas.1706657114.

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The subject of topological materials has attracted immense attention in condensed-matter physics because they host new quantum states of matter containing Dirac, Majorana, or Weyl fermions. Although Majorana fermions can only exist on the surface of topological superconductors, Dirac and Weyl fermions can be realized in both 2D and 3D materials. The latter are semimetals with Dirac/Weyl cones either not tilted (type I) or tilted (type II). Although both Dirac and Weyl fermions have massless nature with the nontrivial Berry phase, the formation of Weyl fermions in 3D semimetals require either time-reversal or inversion symmetry breaking to lift degeneracy at Dirac points. Here we demonstrate experimentally that canted antiferromagnetic BaMnSb2 is a 3D Weyl semimetal with a 2D electronic structure. The Shubnikov–de Hass oscillations of the magnetoresistance give nearly zero effective mass with high mobility and the nontrivial Berry phase. The ordered magnetic arrangement (ferromagnetic ordering in the ab plane and antiferromagnetic ordering along the c axis below 286 K) breaks the time-reversal symmetry, thus offering us an ideal platform to study magnetic Weyl fermions in a centrosymmetric material.

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Bonora, Loriano, Roberto Soldati und Stav Zalel. „Dirac, Majorana, Weyl in 4D“. Universe 6, Nr. 8 (04.08.2020): 111. http://dx.doi.org/10.3390/universe6080111.

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This is a review of some elementary properties of Dirac, Weyl and Majorana spinors in 4D. We focus in particular on the differences between massless Dirac and Majorana fermions, on one side, and Weyl fermions, on the other. We review in detail the definition of their effective actions, when coupled to (vector and axial) gauge fields, and revisit the corresponding anomalies using the Feynman diagram method with different regularisations. Among various well known results we stress in particular the regularisation independence in perturbative approaches, while not all the regularisations fit the non-perturbative ones. As for anomalies, we highlight in particular one perhaps not so well known feature: the rigid relation between chiral and trace anomalies.

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Pandey, Mahul, und Sachindeo Vaidya. „Yang–Mills matrix mechanics and quantum phases“. International Journal of Geometric Methods in Modern Physics 14, Nr. 08 (11.05.2017): 1740009. http://dx.doi.org/10.1142/s0219887817400096.

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The [Formula: see text] Yang–Mills matrix model coupled to fundamental fermions is studied in the adiabatic limit, and quantum critical behavior is seen at special corners of the gauge field configuration space. The quantum scalar potential for the gauge field induced by the fermions diverges at the corners, and is intimately related to points of enhanced degeneracy of the fermionic Hamiltonian. This in turn leads to superselection sectors in the Hilbert space of the gauge field, the ground states in different sectors being orthogonal to each other. The [Formula: see text] Yang–Mills matrix model coupled to two Weyl fermions has three quantum phases. When coupled to a massless Dirac fermion, the number of quantum phases is four. One of these phases is the color-spin locked phase. This paper is an extended version of the lectures given by the second author (SV) at the International Workshop on Quantum Physics: Foundations and Applications, Bangalore, in February 2016, and is based on [1].

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Chen, Xiaomei, und Rui Zhu. „Quantum Pumping with Adiabatically Modulated Barriers in Three-Band Pseudospin-1 Dirac–Weyl Systems“. Entropy 21, Nr. 2 (22.02.2019): 209. http://dx.doi.org/10.3390/e21020209.

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In this work, pumped currents of the adiabatically-driven double-barrier structure based on the pseudospin-1 Dirac–Weyl fermions are studied. As a result of the three-band dispersion and hence the unique properties of pseudospin-1 Dirac–Weyl quasiparticles, sharp current-direction reversal is found at certain parameter settings especially at the Dirac point of the band structure, where apexes of the two cones touch at the flat band. Such a behavior can be interpreted consistently by the Berry phase of the scattering matrix and the classical turnstile mechanism.

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HARADA, KOJI. „EQUIVALENCE BETWEEN THE WESS-ZUMINO-WITTEN MODEL AND TWO CHIRAL BOSONS“. International Journal of Modern Physics A 06, Nr. 19 (10.08.1991): 3399–418. http://dx.doi.org/10.1142/s0217751x91001659.

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We establish the formal equivalence of a bosonized Dirac fermion (the Wess-Zumino-Witten model) to two bosonized Weyl fermions (Sonnenschein’s chiral bosons) in the path integral framework. These two systems can be regarded as gauge-fixed systems of the same gauge-invariant theory. Factorization of the fermion determinant of QCD2 is naturally realized in terms of chiral bosonization, up to a contact term which is necessary for maintaining gauge invariance. Canonical quantization of the gauge-invariantly extended system is performed.

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Reis, João Alfíeres Andrade de Simões dos, und Marco Schreck. „Formal Developments for Lorentz-Violating Dirac Fermions and Neutrinos“. Symmetry 11, Nr. 10 (24.09.2019): 1197. http://dx.doi.org/10.3390/sym11101197.

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The current paper is a technical work that is focused on Lorentz violation for Dirac fermions as well as neutrinos, described within the nonminimal Standard-Model Extension. We intend to derive two theoretical results. The first is the full propagator of the single-fermion Dirac theory modified by Lorentz violation. The second is the dispersion equation for a theory of N neutrino flavors that enables the description of both Dirac and Majorana neutrinos. As the matrix structure of the neutrino field operator is very involved for generic N, we will use sophisticated methods of linear algebra to achieve our objectives. Our main finding is that the neutrino dispersion equation has the same structure in terms of Lorentz-violating operators as that of a modified single-fermion Dirac theory. The results will be valuable for phenomenological studies of Lorentz-violating Dirac fermions and neutrinos.

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Gao, Lan-Lan, und Xu-Guang Huang. „Chiral Anomaly in Non-Relativistic Systems: Berry Curvature and Chiral Kinetic Theory“. Chinese Physics Letters 39, Nr. 2 (01.02.2022): 021101. http://dx.doi.org/10.1088/0256-307x/39/2/021101.

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Chiral anomaly and the novel quantum phenomena it induces have been widely studied for Dirac and Weyl fermions. In most typical cases, the Lorentz covariance is assumed and thus the linear dispersion relations are maintained. However, in realistic materials, such as Dirac and Weyl semimetals, the nonlinear dispersion relations appear naturally. We develop a kinetic framework to study the chiral anomaly for Weyl fermions with nonlinear dispersions using the methods of Wigner function and semi-classical equations of motion. In this framework, the chiral anomaly is sourced by Berry monopoles in momentum space and could be enhanced or suppressed due to the windings around the Berry monopoles. Our results can help understand the chiral anomaly-induced transport phenomena in non-relativistic systems.

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Dissertationen zum Thema "Dirac and Weyl fermions"

Krizman, Gauthier. „Étude magnéto-optique des transitions de phase topologique dans les alliages Pb₁₋ₓSnₓSe et leurs hétérostructures“. Electronic Thesis or Diss., Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLE019.

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Cette thèse étudie les phases topologiques des alliages de Pb₁₋ₓSnₓSe et de leurs hétérostructures. La caractérisation des propriétés électroniques et topologiques de Pb₁₋ₓSnₓSe est réalisée en magnéto-optique en fonction de plusieurs paramètres internes et externes comme la composition chimique, la contrainte, la température ou le champ magnétique. Les états topologiques d’interface sont caractérisés dans les hétérostructures, et contrôlés via une ingénierie d’hybridation. La polyvalence du système à base de Pb₁₋ₓSnₓSe est mise en évidence. Elle ouvre la voie à l’observation dans de bonnes conditions (grand gap topologique et bonne qualité cristalline) de nombreuses phases pseudo-relativistes de la matière comme l’effet Hall quantique de spin, l’effet Hall quantique anormal ou les fermions de Weyl, …
This thesis deals with topological phases in Pb₁₋ₓSnₓSe alloys and their heterostructures. The topological and electronic properties of Pb₁₋ₓSnₓSe are characterized by using magneto-spectroscopy and numerous external and internal knobs like chemical composition, temperature, strain or magnetic field. The heterostructures are investigated to experimentally reach the topological interface states. A hybridization engineering of these topological interface states is demonstrated in both quantum wells and superlattices. The effect of a magnetic doping is also investigated. The great versatility of the Pb₁₋ₓSnₓSe-based system paves the way for the observation of numerous pseudo-relativistic phases such as quantum spin Hall effect, quantum anomalous Hall effect or Weyl fermions, …

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Broccoli, Matteo. „On the trace anomaly of a Weyl fermion in a gauge background“. Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16408/.

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In this thesis we study the trace anomaly of a Weyl fermion in an abelian gauge background. We first introduce the topic of anomaly in Quantum Fields Theory and provide case studies of a global and a gauge anomaly. Then, we review the lagrangians of the Weyl fermion and Dirac fermion, the models that are the focus of our chiral and trace anomaly computations. Since we evaluate the anomalies using Pauli-Villars (PV) regularization, we present different PV masses and discuss the classical symmetries they break. We identify the differential operators that enter our regularization schemes and we review the method that we use to evaluate anomalies: we read them from the path integral à la Fujikawa and compute them with heat kernel formulas. Then, we evaluate the chiral and trace anomaly of the models we are interested in. The chiral anomaly is well studied in the literature and we reproduce the standard result. The trace anomaly is our original result and, although the presence of the chiral anomaly implies a breakdown of gauge invariance, we find that the trace anomaly can be cast in a gauge invariant form. The issue is analogous to the one recently discussed in the literature about a conjectured contribution of an odd-parity term to the trace anomaly of a Weyl fermion in curved backgrounds. With an abelian gauge background, this odd-parity term would be a Chern-Pontryagin density, that does not appear in our final results.

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Ambrus, Victor E. „Dirac fermions on rotating space-times“. Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/7527/.

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Quantum states of Dirac fermions at zero or finite temperature are investigated using the point-splitting method in Minkowski and anti-de Sitter space-times undergoing rotation about a fixed axis. In the Minkowski case, analytic expressions presented for the thermal expectation values (t.e.v.s) of the fermion condensate, parity violating neutrino current and stress-energy tensor show that thermal states diverge as the speed of light surface (SOL) is approached. The divergence is cured by enclosing the rotating system inside a cylinder located on or inside the SOL, on which spectral and MIT bag boundary conditions are considered. For anti-de Sitter space-time, renormalised vacuum expectation values are calculated using the Hadamard and Schwinger-de Witt methods. An analytic expression for the bi-spinor of parallel transport is presented, with which some analytic expressions for the t.e.v.s of the fermion condensate and stress-energy tensor are obtained. Rotating states are investigated and it is found that for small angular velocities Ω of the rotation, there is no SOL and the thermal states are regular everywhere on the space-time. However, if Ω is larger than the inverse radius of curvature of adS, an SOL forms and t.e.v.s diverge as inverse powers of the distance to it.

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Frenzel, Alex J. „Terahertz Electrodynamics of Dirac Fermions in Graphene“. Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467397.

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Charge carriers in graphene mimic two-dimensional massless Dirac fermions with linear energy dispersion, resulting in unique optical and electronic properties. They exhibit high mobility and strong interaction with electromagnetic radiation over a broad frequency range. Interband transitions in graphene give rise to pronounced optical absorption in the mid-infrared to visible spectral range, where the optical conductivity is close to a universal value $\sigma_0 = \pi e^2/2h$. Free-carrier intraband transitions, on the other hand, cause low-frequency absorption, which varies significantly with charge density and results in strong light extinction at high carrier density. These properties together suggest a rich variety of possible optoelectronic applications for graphene. In this thesis, we investigate the optoelectronic properties of graphene by measuring transient photoconductivity with optical pump-terahertz probe spectroscopy. We demonstrate that graphene exhibits semiconducting positive photoconductivity near zero carrier density, which crosses over to metallic negative photoconductivity at high carrier density. These observations are accounted for by the interplay between photoinduced changes of both the Drude weight and carrier scattering rate. Our findings provide a complete picture to explain the opposite photoconductivity behavior reported in (undoped) graphene grown epitaxially and (doped) graphene grown by chemical vapor deposition. Our measurements also reveal the non-monotonic temperature dependence of the Drude weight in graphene, a unique property of two-dimensional massless Dirac fermions.
Physics

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Bhaseen, Miraculous Joseph. „Logarithmic conformal field theories of disordered Dirac fermions“. Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393358.

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Khalil, Lama. „Ultrafast study of Dirac fermions in topological insulators“. Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS344/document.

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Cette thèse présente une étude expérimentale des propriétés électroniques de deux matériaux topologiques, notamment l’isolant topologique tridimensionnel irradié Bi₂Te₃ et le super-réseau topologique naturel Sb₂Te. Les deux systèmes ont été étudiés par des techniques basées sur la spectroscopie de photoémission. Les composés Bi₂Te₃ ont été irradiés par des faisceaux d’électrons de haute énergie. L’irradiation avec des faisceaux d’électrons est une approche très prometteuse pour réaliser des matériaux qui sont vraiment isolants dans le volume, afin de mettre en évidence le transport quantique dans les états de surface protégés. En étudiant une série d’échantillons de Bi₂Te₃ par la technique de spectroscopie de photoémission résolue en temps et en angle (trARPES), nous montrons que les propriétés topologiques des états de surface de Dirac sont conservées après irradiation électronique, mais leurs dynamiques ultra-rapides de relaxation sont très sensibles aux modifications reliées aux propriétés du volume. De plus, nous avons étudié la structure électronique des bandes occupées et inoccupées du Sb₂Te. En utilisant la microscopie de photoémission d’électrons à balayage (SPEM), nous avons constamment trouvé diverses régions non équivalentes sur la même surface après avoir clivé plusieurs monocristaux de Sb₂Te. Nous avons pu identifier trois terminaisons distinctes caractérisées par différents rapports stœchiométriques de surface Sb/Te et possédant des différences claires dans leurs structures de bandes. Pour la terminaison dominante riche en tellure, nous avons également fourni une observation directe des états électroniques excités et de leurs dynamiques de relaxation en ayant recours à la technique trARPES. Nos résultats indiquent clairement que la structure électronique de surface est fortement affectée par les propriétés du volume du super-réseau. Par conséquent, pour les deux systèmes, nous montrons que la structure électronique de surface est absolument connectée aux propriétés du volume
This thesis presents an experimental study of the electronic properties of two topological materials, namely, the irradiated three-dimensional topological insulator Bi₂Te₃ and the natural topological superlattice phase Sb₂Te. Both systems were investigated by techniques based on photoemission spectroscopy. The Bi₂Te₃ compounds have been irradiated by high-energy electron beams. Irradiation with electron beams is a very promising approach to realize materials that are really insulating in the bulk, in order to emphasize the quantum transport in the protected surface states. By studying a series of samples of Bi₂Te₃ using time- and angle-resolved photoemission spectroscopy (trARPES) we show that, while the topological properties of the Dirac surface states are preserved after electron irradiation, their ultrafast relaxation dynamics are very sensitive to the related modifications of the bulk properties. Furthermore, we have studied the occupied and unoccupied electronic band structure of Sb₂Te. Using scanning photoemission microscopy (SPEM), we have consistently found various nonequivalent regions on the same surface after cleaving several Sb₂Te single crystals. We were able to identify three distinct terminations characterized by different Sb/Te surface stoichiometric ratios and with clear differences in their band structure. For the dominating Te-rich termination, we also provided a direct observation of the excited electronic states and of their relaxation dynamics by means of trARPES. Our results clearly indicate that the surface electronic structure is strongly affected by the bulk properties of the superlattice. Therefore, for both systems, we show that the surface electronic structure is absolutely connected to the bulk properties

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Bocquet, Marc. „Chaînes de Spins, Fermions de Dirac, et Systèmes Désordonnés“. Phd thesis, Ecole Polytechnique X, 2000. http://tel.archives-ouvertes.fr/tel-00001560.

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La première partie de cette thèse traite des chaînes de spins quantiques. On étudie tout d'abord des systèmes de spins quantiques qui sont reliés de façon continue à la chaîne de Heisenberg s=1. La construction d'un modèle sigma non-linéaire permet d'estimer le gap de ces systèmes. On étudie ensuite une chaîne de spins s=1/2 dopée par des impuretés non-magnétiques possédant un spin nucléaire. A l'aide de techniques de bosonisation, on calcule analytiquement le temps de relaxation longitudinal d'une impureté en fonction de la température, corrections logarithmiques incluses. Ce type d'analyse est également mené sur un liquide de Luttinger chiral, modélisant par exemple un demi-fil quantique. La deuxième partie est consacrée aux systèmes désordonnées en basse dimension. Des liens formels sont éclaircis entre modèle désordonné sur réseau, fermions de Dirac en milieu aléatoire, chaînes de spins supersymétriques non-compactes et modèle sigma non-linéaire. Le détail des calculs est donné sur l'exemple de la transition entre plateaux de l'effet Hall quantique entier. On calcule ensuite exactement les densités d'états et les longueurs de localisation typiques d'un fermion de Dirac en dimension 1 dans des potentiels aléatoires de différentes natures. De nombreux modèles de théorie de la matière condensée, comme par exemple la chaîne XX désordonnée, se ramènent à ce système. Puis nous étudions les fermions de Dirac en dimension 2 en milieu aléatoire. Plus particulièrement, nous analysons le cas de fermions en masse aléatoire. Ce modèle décrit les excitations de basse énergie d'un supraconducteur d'onde $d$ dont les impuretés sont magnétiques. Un diagramme de phase est proposé. Il s'articule autour du point tricritique des fermions de Dirac libres et fait apparaître une phase métallique thermique inattendue.

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Steiner, Margit Susanne. „Random Dirac fermions and localisation phenomena in one dimension“. Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325365.

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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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We present an effective field theory for interacting electrons in clean semimetals (both three dimensional Dirac semimetals and graphene) in terms of their soft or massless bosonic degrees of freedom. We show, by means of a Ward identity, that the intrinsic semimetal ground state breaks the Sp(4M) symmetry of the theory. In Fermi liquids this enables one to identify the massive, non-Goldstone modes of the theory and integrate them out. Due to the vanishing density of states in semimetals, unlike in Fermi liquids, both Goldstone and non-Goldstone modes are equally soft, and so all two-particle correlations need to be kept. The resulting theory is not perturbative with respect to the electron-electron interaction; rather, it is controlled by means of a systematic loop expansion and allows one to determine the exact asymptotic form of observables in the limits of small frequencies and/or wave vectors. Equivalently, it provides a mechanism of determining the long time-tail and long wavelength behavior of observables and excitations. As a representative application, we use the theory to compute the zero-bias anomaly for the density of states for both short and long-range interactions in two and three dimensions. We find that the leading nonanalyticity in semimetals with a long-ranged interaction appears at the same order in frequency as the one in Fermi liquids, since the effects of the vanishing density of states at the Fermi level are offset by the breakdown of screening. Consequently, we are able to provide a logical scheme to determine the leading non-analytical behavior of observables in semimetals using knowledge of the corresponding non-analyticities in a Fermi liquid.
2020-01-11

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Mizobata, William Nobuhiro. „Interação entre impurezas enterradas em um semimetal de Weyl : caso magnético /“. Ilha Solteira, 2019. http://hdl.handle.net/11449/181343.

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Orientador: Antônio Carlos Ferreira Seridonio
Resumo: 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

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Bücher zum Thema "Dirac and Weyl fermions"

Israelit, Mark. The Weyl-Dirac theory and our universe. Commack, N.Y: Nova Science Publishers, 1999.

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Kachelriess, Michael. Fermions and the Dirac equation. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198802877.003.0008.

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Starting from the spinor representation of the Lorentz group,Weyl spinors and their transformation properties are derived. The Dirac equation and the properties of its solutions are discussed. Graßmann numbers and the gener-ating functional for fermions are introduced. Weyl and Majorana fermions are examined.

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Electronic Properties of Dirac and Weyl Semimetals. World Scientific Publishing Co Pte Ltd, 2021.

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Wurm, Jurgen. Dirac Fermions in Graphene Nanostructures: Edge Effects on Spectral Density and Quantum Transport. Universitatsverlag Regensburg, 2011.

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Baulieu, Laurent, John Iliopoulos und Roland Sénéor. Towards a Relativistic Quantum Mechanics. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198788393.003.0007.

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Towards a relativistic quantum mechanics. Klein–Gordon and the problems of the probability current and the negative energy solutions. The Dirac equation and negative energies. P, C, and T symmetries. Positrons. The Schrödinger equation as the non-relativistic limit of relativistic equations. Majorana and Weyl equations. Relativistic corrections in hydrogen-like atoms. The Dirac equation as a quantum system with an infinite number of degrees of freedom.

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Zirnbauer, Martin R. Symmetry classes. Herausgegeben von Gernot Akemann, Jinho Baik und Philippe Di Francesco. Oxford University Press, 2018. http://dx.doi.org/10.1093/oxfordhb/9780198744191.013.3.

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This article examines the notion of ‘symmetry class’, which expresses the relevance of symmetries as an organizational principle. In his 1962 paper The threefold way: algebraic structure of symmetry groups and ensembles in quantum mechanics, Dyson introduced the prime classification of random matrix ensembles based on a quantum mechanical setting with symmetries. He described three types of independent irreducible ensembles: complex Hermitian, real symmetric, and quaternion self-dual. This article first reviews Dyson’s threefold way from a modern perspective before considering a minimal extension of his setting to incorporate the physics of chiral Dirac fermions and disordered superconductors. In this minimally extended setting, Hilbert space is replaced by Fock space equipped with the anti-unitary operation of particle-hole conjugation, and symmetry classes are in one-to-one correspondence with the large families of Riemannian symmetric spaces.

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Kübler, Jürgen. Theory of Itinerant Electron Magnetism, 2nd Edition. 2. Aufl. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780192895639.001.0001.

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The book, in the broadest sense, is an application of quantum mechanics and statistical mechanics to the field of magnetism. Under certain well-described conditions, an immensely large number of electrons moving in the solid will collectively produce permanent magnetism. Permanent magnets are of fundamental interest, and magnetic materials are of great practical importance as they provide a large field of technological applications. The physical details describing the many-electron problem of magnetism are presented in this book on the basis of the density-functional approximation. The emphasis is on realistic magnets, for which the equations describing properties of the many-electron problem can only be solved by using computers. The great recent and continuing improvements are, to a very large extent, responsible for the progress in this field. Along with an introduction to the density-functional theory, the book describes representative computational methods and detailed formulas for physical properties of magnets, which include among other things the computation of magnetic ordering temperatures, the giant magnetoresistance, magneto-optical effects, weak ferromagnetism, the anomalous Hall and Nernst effects, and novel quasiparticles, such as Weyl fermions and magnetic skyrmions.

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Buchteile zum Thema "Dirac and Weyl fermions"

Pronin, Artem V. „Dirac and Weyl Semimetals“. In Springer Series in Solid-State Sciences, 45–81. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-35637-7_3.

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Shen, Shun-Qing. „Topological Dirac and Weyl Semimetals“. In Springer Series in Solid-State Sciences, 207–29. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-4606-3_11.

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Wolschin, Georg. „Dirac-Neutrinos: Die Weyl-Gleichung“. In Relativistische Quantenmechanik, 101–9. Berlin, Heidelberg: Springer Berlin Heidelberg, 2021. http://dx.doi.org/10.1007/978-3-662-64387-7_8.

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Wolschin, Georg. „Dirac-Neutrinos: Die Weyl-Gleichung“. In Relativistische Quantenmechanik, 97–105. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-47108-1_8.

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Kobayashi, Takayoshi. „Dirac Fermions Near the Dirac Point in Topological Insulators“. In Ultrashort Pulse Lasers and Ultrafast Phenomena, 487–94. Boca Raton: CRC Press, 2023. http://dx.doi.org/10.1201/9780429196577-69.

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Johnson, P. D. „Dirac cones and topological states: Dirac and Weyl semimetals“. In Physics of Solid Surfaces, 535–45. Berlin, Heidelberg: Springer Berlin Heidelberg, 2018. http://dx.doi.org/10.1007/978-3-662-53908-8_128.

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Bhaseen, M. J., J. S. Caux, I. I. Kogan und A. M. Tsvelik. „Disordered Dirac Fermions: Three Different Approaches“. In New Theoretical Approaches to Strongly Correlated Systems, 173–203. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0838-9_8.

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Litvinov, Vladimir. „Indirect Exchange Interaction Mediated by Dirac Fermions“. In Magnetism in Topological Insulators, 117–42. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-12053-5_7.

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Serban, Didina. „2D Random Dirac Fermions: Large N Approach“. In Statistical Field Theories, 263–75. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0514-2_24.

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Isobe, Hiroki. „Interacting Dirac Fermions in (3+1) Dimensions“. In Theoretical Study on Correlation Effects in Topological Matter, 33–62. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-3743-6_2.

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Konferenzberichte zum Thema "Dirac and Weyl fermions"

Buividovich, P. V. „Surface states of massive Dirac fermions with separated Weyl nodes“. In XITH CONFERENCE ON QUARK CONFINEMENT AND HADRON SPECTRUM. AIP Publishing LLC, 2016. http://dx.doi.org/10.1063/1.4938609.

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Belyanin, Alexey. „Magnetooptics of materials with Dirac and Weyl fermions (Conference Presentation)“. In Spintronics XV, herausgegeben von Henri-Jean M. Drouhin, Jean-Eric Wegrowe und Manijeh Razeghi. SPIE, 2022. http://dx.doi.org/10.1117/12.2634322.

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Kumar, Upendra, Vipin Kumar, Enamullah und Girish S. Setlur. „Bloch-Siegert shift in Dirac-Weyl fermionic systems“. In DAE SOLID STATE PHYSICS SYMPOSIUM 2017. Author(s), 2018. http://dx.doi.org/10.1063/1.5029045.

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Matos, Tonatiuh, Omar Gallegos und Pierre-Henri Chavanis. „Hydrodynamic representation and energy balance for the Dirac and Weyl fermions in curved space-times“. In Proceedings of the MG16 Meeting on General Relativity. WORLD SCIENTIFIC, 2023. http://dx.doi.org/10.1142/9789811269776_0201.

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Nagaosa, Naoto. „Correlated Weyl Fermions in Oxides“. In Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2019). Journal of the Physical Society of Japan, 2020. http://dx.doi.org/10.7566/jpscp.30.011007.

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Akrap, Ana. „Magneto-optics of Dirac and Weyl semimetals“. In Terahertz Emitters, Receivers, and Applications XI, herausgegeben von Manijeh Razeghi und Alexei N. Baranov. SPIE, 2020. http://dx.doi.org/10.1117/12.2569451.

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LeClair, Andre. „Renormalization Group for disordered Dirac Fermions“. In Workshop on Integrable Theories, Solitons and Duality. Trieste, Italy: Sissa Medialab, 2002. http://dx.doi.org/10.22323/1.008.0022.

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Ong, N. Phuan. „The Chiral Anomaly in Dirac and Weyl Semimetals“. In Nobel Symposium 167: Chiral Matter. WORLD SCIENTIFIC, 2023. http://dx.doi.org/10.1142/9789811265068_0008.

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Luo, C. W., H. J. Wang, S. A. Ku, H. J. Chen, T. T. Yeh, J. Y. Lin, K. H. Wu et al. „Snapshots of Dirac Fermions near the Dirac Point in Topological Insulators“. In International Conference on Ultrafast Phenomena. Washington, D.C.: OSA, 2014. http://dx.doi.org/10.1364/up.2014.08.tue.p2.31.

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Catterall, Simon. „Dirac-Kahler fermions and exact lattice supersymmetry“. In XXIIIrd International Symposium on Lattice Field Theory. Trieste, Italy: Sissa Medialab, 2005. http://dx.doi.org/10.22323/1.020.0006.

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Berichte der Organisationen zum Thema "Dirac and Weyl fermions"

Huang, Lunan. Studies of Dirac and Weyl fermions by angle resolved photoemission spectroscopy. Office of Scientific and Technical Information (OSTI), Januar 2016. http://dx.doi.org/10.2172/1342554.

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Horng, Jason, Chi-Fan Chen, Baisong Geng, Caglar Girit, Yuanbo Zhang, Zhao Hao, Hans A. Bechtel, Michael Martin, Alex Zettl und Michael F. Crommie. Drude Conductivity of Dirac Fermions in Graphene. Fort Belvoir, VA: Defense Technical Information Center, Januar 2010. http://dx.doi.org/10.21236/ada526672.

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Vekhter, Ilya. Inhomogeneous disorder Dirac Fermions: from heavy fermion superconductors to graphene. Final report. Office of Scientific and Technical Information (OSTI), August 2013. http://dx.doi.org/10.2172/1089679.

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Mishchenko, Eugene. Disorder, interactions, and their interplay in novel narrow-gap Dirac materials and Weyl semimetals. Office of Scientific and Technical Information (OSTI), März 2022. http://dx.doi.org/10.2172/1856847.

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