Magnetic Field Effects in Low-Dimensional Quantum Magnets
Magnetic Field Effects in Low-Dimensional Quantum Magnets

Author: Adam Iaizzi

Publisher: Springer

Published: 2018-11-28

Total Pages: 156

ISBN-13: 3030018032

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This thesis is a tour-de-force combination of analytic and computational results clarifying and resolving important questions about the nature of quantum phase transitions in one- and two-dimensional magnetic systems. The author presents a comprehensive study of a low-dimensional spin-half quantum antiferromagnet (the J-Q model) in the presence of a magnetic field in both one and two dimensions, demonstrating the causes of metamagnetism in such systems and providing direct evidence of fractionalized excitations near the deconfined quantum critical point. In addition to describing significant new research results, this thesis also provides the non-expert with a clear understanding of the nature and importance of computational physics and its role in condensed matter physics as well as the nature of phase transitions, both classical and quantum. It also contains an elegant and detailed but accessible summary of the methods used in the thesis—exact diagonalization, Monte Carlo, quantum Monte Carlo and the stochastic series expansion—that will serve as a valuable pedagogical introduction to students beginning in this field.

Characterizing Ground States of Low-dimensional Quantum Magnets
Characterizing Ground States of Low-dimensional Quantum Magnets

Author: Hyejin Ju

Publisher:

Published: 2013

Total Pages: 196

ISBN-13: 9781303052262

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The study of frustration in quantum magnetism has been the focus of extensive research in the past couple of decades. The class of materials in this category is typically strongly correlated, due to strong electron-electron repulsion. In one- and two-dimensions, quantum fluctuations dominate these systems, and often, semi-classical approximations become an oversimplification. This thesis is concerned with exploring exotic physics that can emerge in low-dimensional quantum magnets. First, we use a T = 0 projected Monte Carlo algorithm in the valence bond basis to study the entanglement scaling of two-dimensional (2d) gapless systems. In particular, we focus on the resonating-valence-bond wavefunction as well as the gapless Goldstone mode in the Heisenberg model on the square lattice. We find that, in addition to the area law, there is a subleading, shape-dependent piece to the entanglement entropy, which is reminiscent of one dimensional (1d) gapless systems. We then explore the Heisenberg model under an applied magnetic field on the quasi-1d problem of a three-leg triangular spin tube (TST), using extensive density-matrix-renormalization group calculations coupled with analytical arguments to describe the results. We find that the physics describing this model differs from some of the well-known results on the two dimensional lattice, especially near low magnetic fields and at 1/3 magnetization. Finally, further research and possibilities in numerical techniques are discussed.

Fundamentals of Low Dimensional Magnets
Fundamentals of Low Dimensional Magnets

Author: Ram K. Gupta

Publisher: CRC Press

Published: 2022-08-29

Total Pages: 380

ISBN-13: 1000640175

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A low-dimensional magnet is a key to the next generation of electronic devices. In some respects, low-dimensional magnets refer to nanomagnets (nanostructured magnets) or single-molecule magnets (molecular nanomagnets). They also include the group of magnetic nanoparticles, which have been widely used in biomedicine, technology, industries, and environmental remediation. Low-dimensional magnetic materials can be used effectively in the future in powerful computers (hard drives, magnetic random-access memory, ultra-low power consumption switches, etc.). The properties of these materials largely depend on the doping level, phase, defects, and morphology. This book covers various nanomagnets and magnetic materials. The basic concepts, various synthetic approaches, characterizations, and mathematical understanding of nanomaterials are provided. Some fundamental applications of 1D, 2D, and 3D materials are covered. This book provides the fundamentals of low-dimensional magnets along with synthesis, theories, structure-property relations, and applications of ferromagnetic nanomaterials. This book broadens our fundamental understanding of ferromagnetism and mechanisms for realization and advancement in devices with improved energy efficiency and high storage capacity.

High Magnetic Field Science and Its Application in the United States
High Magnetic Field Science and Its Application in the United States

Author: National Research Council

Publisher: National Academies Press

Published: 2013-12-25

Total Pages: 233

ISBN-13: 0309286344

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The Committee to Assess the Current Status and Future Direction of High Magnetic Field Science in the United States was convened by the National Research Council in response to a request by the National Science Foundation. This report answers three questions: (1) What is the current state of high-field magnet science, engineering, and technology in the United States, and are there any conspicuous needs to be addressed? (2) What are the current science drivers and which scientific opportunities and challenges can be anticipated over the next ten years? (3) What are the principal existing and planned high magnetic field facilities outside of the United States, what roles have U.S. high field magnet development efforts played in developing those facilities, and what potentials exist for further international collaboration in this area? A magnetic field is produced by an electrical current in a metal coil. This current exerts an expansive force on the coil, and a magnetic field is "high" if it challenges the strength and current-carrying capacity of the materials that create the field. Although lower magnetic fields can be achieved using commercially available magnets, research in the highest achievable fields has been, and will continue to be, most often performed in large research centers that possess the materials and systems know-how for forefront research. Only a few high field centers exist around the world; in the United States, the principal center is the National High Magnetic Field Laboratory (NHMFL). High Magnetic Field Science and Its Application in the United States considers continued support for a centralized high-field facility such as NHFML to be the highest priority. This report contains a recommendation for the funding and siting of several new high field nuclear magnetic resonance magnets at user facilities in different regions of the United States. Continued advancement in high-magnetic field science requires substantial investments in magnets with enhanced capabilities. High Magnetic Field Science and Its Application in the United States contains recommendations for the further development of all-superconducting, hybrid, and higher field pulsed magnets that meet ambitious but achievable goals.

Opportunities in High Magnetic Field Science
Opportunities in High Magnetic Field Science

Author: National Research Council

Publisher: National Academies Press

Published: 2005-07-26

Total Pages: 188

ISBN-13: 0309165318

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High-field magnetsâ€"those that operate at the limits of the mechanical and/or electromagnetic properties of their structural materialsâ€"are used as research tools in a variety of scientific disciplines. The study of high magnetic fields themselves is also important in many areas such as astrophysics. Because of their importance in scientific research and the possibility of new breakthroughs, the National Science Foundation asked the National Research Council to assess the current state of and future prospects for high-field science and technology in the United States. This report presents the results of that assessment. It focuses on scientific and technological challenges and opportunities, and not on specific program activities. The report provides findings and recommendations about important research directions, the relative strength of U.S. efforts compared to other countries, and ways in which the program can operate more effectively.

Magnetic Exchange Disorder in Low-dimensional Quantum Magnets
Magnetic Exchange Disorder in Low-dimensional Quantum Magnets

Author:

Publisher:

Published: 2017

Total Pages:

ISBN-13:

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Low-dimensional quantum magnetism is currently of great interest due to the fact that reduced dimensionality can support strong quantum fluctuations, which may lead to unusual phenomena and quantum-critical behavior. The effect of random exchange strengths in two-dimensional (2D) antiferromagnets is still not fully understood despite much effort. This project aims to rectify this by investigating the high-field properties of the 2D coordination polymer (QuinH)2Cu(ClxBr1-x)4.2H2O. The exchange pathway is through Cu-Halide-Cu bonds, and by randomizing the proportion of chlorine and bromine atoms in the unit cell, disorder can be introduced into the system.

Quantum Magnetism
Quantum Magnetism

Author: Ulrich Schollwöck

Publisher: Springer

Published: 2008-05-14

Total Pages: 488

ISBN-13: 3540400664

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Closing a gap in the literature, this volume is intended both as an introductory text at postgraduate level and as a modern, comprehensive reference for researchers in the field. Provides a full working description of the main fundamental tools in the theorists toolbox which have proven themselves on the field of quantum magnetism in recent years. Concludes by focusing on the most important cuurent materials form an experimental viewpoint, thus linking back to the initial theoretical concepts.

High Magnetic Fields
High Magnetic Fields

Author: Claude Berthier

Publisher: Springer Science & Business Media

Published: 2001

Total Pages: 503

ISBN-13: 354043979X

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The quantum Hall effect, low-dimensional systems, vortices and superconductivity, high-resolution NMR and EPR spectroscopy - all these and many other landmark contributions of high-magnetic-field physics to solid state science, analytical chemistry and structural biology are presented in this book. Each chapter describes the key concepts and future prospects in the corresponding field. The text can be read at different levels: researchers will find depth and insight, while students will come to understand the basic concepts. This book, written by leading scientists, will serve as a reference work on high-magnetic-field science for many years to come.