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Author : Lars Fritz
Publisher :
ISBN 13 :
Total Pages : 247 pages
Book Rating : 4.:/5 (637 download)
Download or read book Quantum Phase Transitions in Models of Magnetic Impurities written by Lars Fritz and published by . This book was released on 2006 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Mengxing Cheng
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (741 download)
Download or read book Quantum Phase Transitions of Magnetic Impurities in Dissipative Environments written by Mengxing Cheng and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For the Ohmic case s = 1, the transition is instead of Kosterlitz-Thouless type. (iii) Away from particle-hole symmetry, the quantum phase transition is replaced by a smooth crossover, but signatures of the symmetric quantum critical point remain in the physical properties at elevated temperatures and/or frequencies. In the pseudogap Anderson-Holstein model, a magnetic impurity level hybridizes with a fermionic host whose density of states vanishes as ... r at the Fermi energy (... = 0) and is also coupled, via the impurity charge, to a local boson mode. We find that the pseudogap Anderson-Holstein model shows distinctive low-temperature quantum fluctuations in two regimes, depending on the strength of the impurity-boson coupling. We study two cases of band exponents: 0
Download or read book Magnetic Field Induced Quantum Phase Transitions in the Two-impurity Anderson Model written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the two-impurity Anderson model, the inter-impurity spin exchange interaction favors a spin singlet state between two impurities leading to the localization of quasiparticles. We show that a local uniform magnetic field can delocalize the quasiparticies to restore the Kondo resonance. This transition is found to be continuous, accompanied by not only the divergence of the staggered (anti ferromagnetic) susceptibility, but also the divergence of the uniform spin susceptibility. This implies that the magnetic field induced quantum phase transitions in Kondo systems are in favor of the local critical type.
Author : Subir Sachdev
Publisher : Cambridge University Press
ISBN 13 : 9780521004541
Total Pages : 374 pages
Book Rating : 4.0/5 (45 download)
Download or read book Quantum Phase Transitions written by Subir Sachdev and published by Cambridge University Press. This book was released on 2001-04-23 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum Phase Transitions is the first book to describe in detail the fundamental changes that can occur in the macroscopic nature of matter at zero temperature due to small variations in a given external parameter. The subject plays a central role in the study of the electrical and magnetic properties of numerous important solid state materials. The author begins by developing the theory of quantum phase transitions in the simplest possible class of non-disordered, interacting systems - the quantum Ising and rotor models. Particular attention is paid to their non-zero temperature dynamic and transport properties in the vicinity of the quantum critical point. Several other quantum phase transitions of increasing complexity are then discussed and clarified. Throughout, the author interweaves experimental results with presentation of theoretical models, and well over 500 references are included. The book will be of great interest to graduate students and researchers in condensed matter physics.
Author : Lincoln Carr
Publisher : CRC Press
ISBN 13 : 1439802610
Total Pages : 756 pages
Book Rating : 4.4/5 (398 download)
Download or read book Understanding Quantum Phase Transitions written by Lincoln Carr and published by CRC Press. This book was released on 2010-11-02 with total page 756 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum phase transitions (QPTs) offer wonderful examples of the radical macroscopic effects inherent in quantum physics: phase changes between different forms of matter driven by quantum rather than thermal fluctuations, typically at very low temperatures. QPTs provide new insight into outstanding problems such as high-temperature superconductivit
Author : Manal M. Al-Ali
Publisher :
ISBN 13 :
Total Pages : 119 pages
Book Rating : 4.:/5 (87 download)
Download or read book Quantum Phase Transitions in Impurity Models and Percolating Lattices written by Manal M. Al-Ali and published by . This book was released on 2013 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This thesis investigates the influence of random disorder and dissipation on zero-temperature quantum phase transitions. Both phenomena can fundamentally change the character of the phases of a quantum many-particle system and of the transitions between them. If dissipation and disorder occur simultaneously in a system undergoing a quantum phase transition, particularly strong effects can be expected. In the first paper reproduced in this thesis, we study a single quantum rotor coupled to a sub-Ohmic dissipative bath. We find that this system undergoes a quantum phase transition from a delocalized phase to a localized phase as the dissipation strength is increased. We determine the exact critical behavior of this transition; it agrees with that of the corresponding long-range interacting classical model. Therefore, the quantum-to-classical mapping is valid for the sub-Ohmic rotor model. In the second paper, we investigate the influence of sub-Ohmic dissipation on randomly diluted quantum Ising and rotor models. We find that the zero-temperature quantum phase transition across the lattice percolation threshold separates an unusual super-paramagnetic cluster phase from an inhomogeneous ferromagnetic phase. We determine the low-temperature thermodynamic behavior in both phases, and we relate our results to the smeared transition scenario for disordered quantum phase transitions. In the last paper, the influence of Ohmic dissipation on the random transverse-field Ising chain is studied by means of large-scale Monte-Carlo simulations. Our simulations show that Ohmic dissipation destroys the infinite-randomness quantum critical point of the dissipationless system. Instead, the quantum phase transition between the paramagnetic and ferromagnetic phases is smeared, as predicted by a recent strong-disorder renormalization group approach"--Abstract, page iv.
Author : Lars Fritz
Publisher :
ISBN 13 :
Total Pages : 247 pages
Book Rating : 4.:/5 (123 download)
Download or read book Quantum Phase Transtitions in Models of Magnetic Impurities written by Lars Fritz and published by . This book was released on 2006 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Sei Suzuki
Publisher : Springer
ISBN 13 : 9783642330407
Total Pages : 403 pages
Book Rating : 4.3/5 (34 download)
Download or read book Quantum Ising Phases and Transitions in Transverse Ising Models written by Sei Suzuki and published by Springer. This book was released on 2012-12-14 with total page 403 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum phase transitions, driven by quantum fluctuations, exhibit intriguing features offering the possibility of potentially new applications, e.g. in quantum information sciences. Major advances have been made in both theoretical and experimental investigations of the nature and behavior of quantum phases and transitions in cooperatively interacting many-body quantum systems. For modeling purposes, most of the current innovative and successful research in this field has been obtained by either directly or indirectly using the insights provided by quantum (or transverse field) Ising models because of the separability of the cooperative interaction from the tunable transverse field or tunneling term in the relevant Hamiltonian. Also, a number of condensed matter systems can be modeled accurately in this approach, hence granting the possibility to compare advanced models with actual experimental results. This work introduces these quantum Ising models and analyses them both theoretically and numerically in great detail. With its tutorial approach the book addresses above all young researchers who wish to enter the field and are in search of a suitable and self-contained text, yet it will also serve as a valuable reference work for all active researchers in this area.
Author : Bikas K. Chakrabarti
Publisher : Springer Science & Business Media
ISBN 13 : 3540498656
Total Pages : 217 pages
Book Rating : 4.5/5 (44 download)
Download or read book Quantum Ising Phases and Transitions in Transverse Ising Models written by Bikas K. Chakrabarti and published by Springer Science & Business Media. This book was released on 2008-12-22 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigations into the zero-temperature phases in various frustrated and random Ising models in a transverse or tunnelling field have caught attention very recently in the context of quantum magnetisation of glasses and other frustrated systems. This book gives a detailed discussion of the various theoretical techniques developed for the study of transverse Ising models and of the results of these studies with regular and random frustration, dilution, randomness, etc. Recent developments in the studies on their (quantum) relaxational dynamics, such as in quantum hysteresis, are also treated. The detailed presentation of original results and the reviews given here are expected to inspire further research in the exciting field of quantum many-body systems with randomness and frustration.
Author : Conradin Kraemer
Publisher :
ISBN 13 :
Total Pages : 128 pages
Book Rating : 4.:/5 (729 download)
Download or read book Quantum Phase Transitions in a Magnetic Model System written by Conradin Kraemer and published by . This book was released on 2009 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Alex C. Hewson
Publisher : Springer Science & Business Media
ISBN 13 : 9401002134
Total Pages : 364 pages
Book Rating : 4.4/5 (1 download)
Download or read book Concepts in Electron Correlation written by Alex C. Hewson and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: The NATO sponsored Advanced Research Workshop on "Concepts in Electron Correlation" took place on the Croatian island of Hvar during the period from the 29th of September to the 3rd of October, 2002. The topic of electron correlation is a fundamental one in the field of condensed matter, and one that is being very actively studied both experimentally and theoretically at the present time. The manifestations of electron cor relation are diverse, and play an important role in systems ranging from high temperature superconductors, heavy fermions, manganite compounds with colossal magnetoresistance, transition metal compounds with metal insulator transitions, to mesoscopic systems and quantum dots. The aim of the workshop was to provide an opportunity for a dialogue between exper imentalists and theoreticians to assess the current state of understanding, and to set an agenda for future work. There was also a follow-up workshop on the same topic where the presentations included more background and introductory material for younger researchers in the field. The papers presented in these proceedings clearly demonstrate the di versity of current research on electron correlation. They show that real progress is being made in characterising systems experimentally and in developing theoretical approaches for a quantitative comparison with ex periment. The more one learns, however, the more there is to understand, and many of the contributions help to map out the territory which has yet to be explored. We hope that the articles in this volume will be a stimulus for such future work.
Author : A S Shumovsky
Publisher : World Scientific
ISBN 13 : 9814507660
Total Pages : 253 pages
Book Rating : 4.8/5 (145 download)
Download or read book Lectures On Phase Transitions written by A S Shumovsky and published by World Scientific. This book was released on 1990-11-30 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book treats the problem of phase transitions, emphasizing the generality and universality of the methods and models used. The course is basically concentrated on the problems of vacuum degeneration in macroscopic systems and a fundamental concept of quasiaverages by Bogolubov playing a special role in the theory of phase transitions and critical phenomena. An analysis of the connection between phase transition and spontaneous symmetry breaking in a macroscopic system allows a unique description of both first- and second-order phase transitions.The unique features of this book are:(i) a unique approach of describing first — as well as second-order phase transitions, based on the Bogolubov concept of quasi-averages.(ii) a detailed presentation of the material and at the same time a review of modern problems.(iii) a general character of developed ideas that could be applied to various particular systems of condensed matter physics, nuclear physics and high-energy physics.
Author : Daivd P Belanger
Publisher : World Scientific
ISBN 13 : 981125950X
Total Pages : 246 pages
Book Rating : 4.8/5 (112 download)
Download or read book Magnetic Phase Transitions In Single Crystals written by Daivd P Belanger and published by World Scientific. This book was released on 2022-07-27 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic crystals are ideal systems to study the universal properties of phase transitions, particularly systems with quenched randomness and frustration. Pure systems with different symmetries provide the foundation for studies in corresponding systems with quenched randomness. Because phenomena near phase transitions have universal properties, results from bulk magnetic crystals provide a basis for understanding phase transitions in films and nanoparticles, as well as many non-magnetic materials.This motivates the subject of this book, which discusses phase transitions studies in magnetic crystals from the perspective of an experimentalist who has done extensive work in the field. The advantage is that many experimental techniques are described in sufficient detail for a good understanding of the results and their comparison to theory.
Author : David P. Landau
Publisher : Springer
ISBN 13 : 9783540326397
Total Pages : 173 pages
Book Rating : 4.3/5 (263 download)
Download or read book Computer Simulation Studies in Condensed-Matter Physics XVIII written by David P. Landau and published by Springer. This book was released on 2006-12-12 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: This status report features the most recent developments in the field, spanning a wide range of topical areas in the computer simulation of condensed matter/materials physics. Both established and new topics are included, ranging from the statistical mechanics of classical magnetic spin models to electronic structure calculations, quantum simulations, and simulations of soft condensed matter.
Author : H. Jeffrey Gardner
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (859 download)
Download or read book Quantum Phase Transitions and Enhancement of Superconductivity by a Parallel Magnetic Field in Two Dimensional Superconductors written by H. Jeffrey Gardner and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: This dissertation describes several studies of superconducting phenomena in two dimensions. We have investigated the superconductor:insulator quantum phase transitions (SITs) tuned by several parameters, namely disorder (d), magnetic field (B), and magnetic impurities (MI). The films have been examined through electrical transport measurements and tunneling spectroscopy. Our experiments are carried out in a unique experimental setup which has allowed us to study these three SITs in situ on the same sample. There are two major theoretical frameworks to describe the superconductor:insulator transitions. One theory calls for a transition from a superconductor to a fermionic insulator. The other points to an bosonic insulator with localized Cooper pairs and itinerant vortices. Our experimental capabilities let us make direct comparisons of the SITs and comment on the nature of transition. We consider the MI:tuned SIT a canonical example of an SIT in the fermionic framework. The resistive transitions in the superconducting state are sharp, the phase boundary is well defined, and the insulating state shows weakly insulating behavior. The B:tuned SIT is representative of a bosonic SIT. In this case, the resistive transitions broaden as magnetic field strength is increased and there is no distinct boundary between the superconducting and insulating phases. Transport reveals a likely activated behavior just on the insulating side of the transition indicative of localized superconductivity. At higher magnetic fields, the temperature dependence weakens, possibly to logarithmic, signaling a break up of Cooper pairs into single electrons. Direct evidence of localized Cooper pairs comes via tunneling spectroscopy measurements on d:tuned granular films where full, bulk superconducting energy gaps are measured in the global insulating state. We have performed transport and tunneling spectroscopy measurements of the d:tuned SIT on amorphous Pb films. The transport behavior is qualitatively similar to what we observed for the MI:tuned SIT. We will also show that our observations of the B:tuned SIT on amorphous Pb films are analogous to the d:tuned SIT on granular films. One goal of our studies was to use tunneling spectroscopy to probe the nature of the insulating states of the d:tuned and MI:tuned SITs. We were only able to complete preliminary measurements on the d:tuned transition, however they are consistent with previous experiments in which increasing disorder leads to a decrease of TC and a concomitant suppression of the normal state density of state (DOS). Our in:house designed and fabricated sample rotation system affords us the opportunity to study the same sample in both perpendicular and parallel magnetic field orientations in situ without breaking vacuum. This capability led us to the observation of parallel magnetic field enhanced superconductivity in amorphous Pb films and the 2:D electron gas at the heteroepitaxial interface of the band insulators LaAlO3 and SrTiO3. We found that the mean field TC of the a:Pb films can be enhanced by as much as 13% above the zero:field value. A qualitatively similar field:enhancement effect has been observed in the LaAlO3/SrTiO3 interfacial superconductor. Moreover, our experiments show the field:enhancement is strongly dependent on the film thickness and magnetic impurity concentration. Clearly, the Bardeen Cooper Schrieffer (BCS) and Ginzburg:Landau (GL) theories of superconductivity do not contain the physics which would account for field:enhanced superconductivity. Presently, we do not have a complete theoretical understanding of the enhancement effect. However, our experimental results have placed significant constraints on any viable theoretical model. In this dissertation, several theoretical explanations of parallel field:enhanced superconductivity are discussed and compared with our observations.
Author : Amit Dutta
Publisher : Cambridge University Press
ISBN 13 : 1316395413
Total Pages : 358 pages
Book Rating : 4.3/5 (163 download)
Download or read book Quantum Phase Transitions in Transverse Field Spin Models written by Amit Dutta and published by Cambridge University Press. This book was released on 2015-01-28 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: The transverse field Ising and XY models (the simplest quantum spin models) provide the organising principle for the rich variety of interconnected subjects which are covered in this book. From a generic introduction to in-depth discussions of the subtleties of the transverse field Ising and related models, it includes the essentials of quantum dynamics and quantum information. A wide range of relevant topics has also been provided: quantum phase transitions, various measures of quantum information, the effects of disorder and frustration, quenching dynamics and the Kibble–Zurek scaling relation, the Kitaev model, topological phases of quantum systems, and bosonisation. In addition, it also discusses the experimental studies of transverse field models (including the first experimental realisation of quantum annealing) and the recent realisation of the transverse field Ising model using tunable Josephson junctions. Further, it points to the obstacles still remaining to develop a successful quantum computer.
Author : Markus Garst
Publisher :
ISBN 13 : 9783832229153
Total Pages : 188 pages
Book Rating : 4.2/5 (291 download)
Download or read book Aspects of Quantum Phase Transitions written by Markus Garst and published by . This book was released on 2004 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:
