Theory of Point Contact Spectroscopy in Correlated Materials PDF Download
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 6
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Book Description
Here, we developed a microscopic theory for the point-contact conductance between a metallic electrode and a strongly correlated material using the nonequilibrium Schwinger-Kadanoff-Baym-Keldysh formalism. We explicitly show that, in the classical limit, contact size shorter than the scattering length of the system, the microscopic model can be reduced to an effective model with transfer matrix elements that conserve in-plane momentum. We found that the conductance dI/dV is proportional to the effective density of states, that is, the integrated single-particle spectral function A([omega] = eV) over the whole Brillouin zone. From this conclusion, we are able to establish the conditions under which a non-Fermi liquid metal exhibits a zero-bias peak in the conductance. Lastly, this finding is discussed in the context of recent point-contact spectroscopy on the iron pnictides and chalcogenides, which has exhibited a zero-bias conductance peak.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 6
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Book Description
Here, we developed a microscopic theory for the point-contact conductance between a metallic electrode and a strongly correlated material using the nonequilibrium Schwinger-Kadanoff-Baym-Keldysh formalism. We explicitly show that, in the classical limit, contact size shorter than the scattering length of the system, the microscopic model can be reduced to an effective model with transfer matrix elements that conserve in-plane momentum. We found that the conductance dI/dV is proportional to the effective density of states, that is, the integrated single-particle spectral function A([omega] = eV) over the whole Brillouin zone. From this conclusion, we are able to establish the conditions under which a non-Fermi liquid metal exhibits a zero-bias peak in the conductance. Lastly, this finding is discussed in the context of recent point-contact spectroscopy on the iron pnictides and chalcogenides, which has exhibited a zero-bias conductance peak.
Author: Yu.G. Naidyuk
Publisher: Springer Science & Business Media
ISBN: 9780387212357
Category : Science
Languages : en
Pages : 320
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Book Description
Various experimental techniques for point contact production are described. Examples of point-contact spectra are presented for pure metals, alloys and compounds, as well as for semimetals and semiconductors, heavy fermion systems, Kond-lattices, mixed valence compounds and more. Superconducting point contacts are considered in respect to Andreev reflection and Josephson effects. Special attention is paid to contact conductance fluctuation, and new trends of research are outlined.
Author: Cheng-Chien Chen
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Strongly correlated systems exhibit novel phenomena such as superconductivity and magnetism that arise from the interplay between many intertwined degrees of freedom. In this dissertation I discuss my work using state-of-the-art exact diagonalization simulations in attempts to understand the physics of correlated materials via their response to various experimental probes. I first discuss simulating x-ray absorption spectra to extract crucial information regarding correlation effects in iron-based superconductors and the pressure-induced phase transitions in hematite. I then discuss modeling resonant inelastic x-ray scattering spectra of the cuprate superconductors and studying the orbital characters of the excitation profiles. Following the discussion of photon-based spectroscopies, I then shift the focus to magnetic properties of iron-based superconductors. I will discuss a possible orbital ordering scenario in connection with the orthorhombic anisotropies observed in neutron scattering, transport, and other spectroscopic experiments performed on these materials. At the end of the dissertation, I examine the role of magnetic frustration and demonstrate how the response of antiferromagnets to non-magnetic impurities and magnetic Raman scattering can reveal the degree of frustration and help narrow the possible models for the iron-pnictide materials.
Author: Mahboob Ashraf
Publisher:
ISBN:
Category : Electron-phonon interactions
Languages : en
Pages : 220
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Author: Adolfo Avella
Publisher: Springer
ISBN: 3662441330
Category : Science
Languages : en
Pages : 329
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Book Description
The continuous evolution and development of experimental techniques is at the basis of any fundamental achievement in modern physics. Strongly correlated systems (SCS), more than any other, need to be investigated through the greatest variety of experimental techniques in order to unveil and crosscheck the numerous and puzzling anomalous behaviors characterizing them. The study of SCS fostered the improvement of many old experimental techniques, but also the advent of many new ones just invented in order to analyze the complex behaviors of these systems. Many novel materials, with functional properties emerging from macroscopic quantum behaviors at the frontier of modern research in physics, chemistry and materials science, belong to this class of systems. The volume presents a representative collection of the modern experimental techniques specifically tailored for the analysis of strongly correlated systems. Any technique is presented in great detail by its own inventor or by one of the world-wide recognized main contributors. The exposition has a clear pedagogical cut and fully reports on the most relevant case study where the specific technique showed to be very successful in describing and enlightening the puzzling physics of a particular strongly correlated system. The book is intended for advanced graduate students and post-docs in the field as textbook and/or main reference, but also for any other researcher in the field who appreciates consulting a single, but comprehensive, source or wishes to get acquainted, in a as painless as possible way, with the working details of a specific technique.
Author: Jamal Berakdar
Publisher: John Wiley & Sons
ISBN: 3527606491
Category : Science
Languages : en
Pages : 255
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Book Description
Here, leading scientists present an overview of the most modern experimental and theoretical methods for studying electronic correlations on surfaces, in thin films and in nanostructures. In particular, they describe in detail coincidence techniques for studying many-particle correlations while critically examining the informational content of such processes from a theoretical point viewpoint. Furthermore, the book considers the current state of incorporating many-body effects into theoretical approaches. Covered topics: -Auger-electron photoelectron coincidence experiments and theories -Correlated electron emission from atoms, fullerens, clusters, metals and wide-band gap materials -Ion coincidence spectroscopies and ion scattering theories from surfaces -GW and dynamical mean-field approaches -Many-body effects in electronic and optical response
Author: A.V. Khotkevich
Publisher: Springer Science & Business Media
ISBN: 146152265X
Category : Science
Languages : en
Pages : 162
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Book Description
The characteristics of electrical contacts have long attracted the attention of researchers since these contacts are used in every electrical and electronic device. Earlier studies generally considered electrical contacts of large dimensions, having regions of current concentration with diameters substantially larger than the characteristic dimensions of the material: the interatomic distance, the mean free path for electrons, the coherence length in the superconducting state, etc. [110]. The development of microelectronics presented to scientists and engineers the task of studying the characteristics of electrical contacts with ultra-small dimensions. Characteristics of point contacts such as mechanical stability under continuous current loads, the magnitudes of electrical fluctuations, inherent sensitivity in radio devices and nonlinear characteristics in connection with electromagnetic radiation can not be understood and altered in the required way without knowledge of the physical processes occurring in contacts. Until recently it was thought that the electrical conductivity of contacts with direct conductance (without tunneling or semiconducting barriers) obeyed Ohm's law. Nonlinearities of the current-voltage characteristics were explained by joule heating of the metal in the region of the contact. However, studies of the current-voltage characteristics of metallic point contacts at low (liquid helium) temperatures [142] showed that heating effects were negligible in many cases and the nonlinear characteristics under these conditions were observed to take the form of the energy dependent probability of inelastic electron scattering, induced by various mechanisms.
Author: Eric C. Faulques
Publisher: Springer Science & Business Media
ISBN: 1402023960
Category : Science
Languages : en
Pages : 422
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Book Description
A comprehensive discussion of the key role of modern spectroscopic investigations in interdisciplinary materials science and engineering, covering emerging materials that are either absolutely novel or well-known materials with recently discovered, exciting properties. The types of spectroscopy discussed include optical, electronic and magnetic, UV-visible absorption, Rayleigh scattering, photoluminescence, vibrational, magnetic resonance, electron energy loss, EXAFS, XANES, optical tomography, time-resolved spectroscopy, and point contact spectroscopy. The materials studied are highly topical, with a focus on carbon and silicon nanomaterials including nanotubes, fullerenes, nanoclusters, metallic superconducting phases, molecular materials, magnetic and charge-stripe oxides, and biomaterials. Theoretical treatments are presented of molecular vibrational dynamics, vibration-induced decay of electronic excited states, nanoscale spin-orbit coupling in 2D Si-based structures, and the growth of semiconductor clusters.
Author: V.P. Mineev
Publisher: CRC Press
ISBN: 9789056992095
Category : Science
Languages : en
Pages : 204
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Book Description
Unconventional superconductivity (or superconductivity with a nontrivial Cooper pairing) is believed to exist in many heavy-fermion materials as well as in high temperature superconductors, and is a subject of great theoretical and experimental interest. The remarkable progress achieved in this field has not been reflected in published monographs and textbooks, and there is a gap between current research and the standard education of solid state physicists in the theory of superconductivity. This book is intended to meet this information need and includes the authors' original results.
Author: Karina Helena Gezina Schulte
Publisher:
ISBN:
Category :
Languages : en
Pages : 172
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Book Description
