Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 40 for “"Spin Liquid"”.
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Magnetic phases of large-spin ultracold bosons: quantum dimer models and spin liquid phases
… the plausibility of producing a quantum spin liquid (QSL) with ultracold bosonic atoms optically confined to the Mott insulating state. QSLs have received a great deal of attention for being an antiferromagnetic groundstate with many exotic properties, including the absence of local …
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The algebraic spin liquid of a possible model description for the normal state of underdoped high temperature superconductors
… background is rooted in Anderson's proposal of spin charge separation as the key emergent phenomenon in cuprate physics. After a brief motivation we look at single particle tunneling into the cuprate's superconducting state from the perspective of both d-wave BCS and the SU(2) slave boson theory …
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Thermodynamic and neutron scattering study of the spin- 1/2 kagome antiferromagnet ZnCu₃(OH)₆Cl₂ : a quantum spin liquid system
New physics, such as a quantum spin liquid, can emerge in systems where quantum fluctuations are enhanced due to reduced dimensionality and strong frustration. The realization of a quantum spin liquid in two-dimensions would represent a new state of matter. It is believed that spin liquid physics …
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Spin liquids, exotic phases and phase transitions
Spin liquid, or featureless Mott-Insulator, is a theoretical state of matter firstly motivated from study on High-Tc superconductor. The most striking property of spin liquids is that they do not break any physical symmetry, yet there are many types of them, meaning a phase transition is necessary …
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Grundzustandseigenschaften von anisotropen antiferromagnetischen Heisenberg-Ketten mit Spin S = 1
In this thesis ground state properties of S = 1 spin chains with exchange and single-ion anisotropy are analysed. Following earlier publications two cases are mainly considered: A fixed ratio of the two anisotropies as well as a fixed and strong exchange anisotropy. The method primarily employed is …
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Terahertz spectroscopy of quantum spin liquids
The optical properties of the spin-1/2 kagome lattice antiferromagnetic Herbertsmithite, ZnCu₃(OH)₆Cl₂, are studied by means of Terahertz Time-Domain Spectroscopy. Herbertsmithite is proposed to exhibit Quantum Spin Liquid behavior, in which electron spins have strong antiferromagnetic …
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Spin liquids : mean field and beyond
Spin liquids are fluid-like ground states of spin systems, where spins do not order at zero temperature. These states have long-range entanglement and concomitant exotic properties, such as fractionalized excitations and emergent gauge field. In this thesis we use mean field approach and its …
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Chern-Simons theory of magnetization plateaus on the kagome lattice
Frustrated spin systems on Kagome lattices have long been considered to be a promising candidate for realizing exotic spin liquid phases. Recently, there has been a lot of renewed interest in these systems with the discovery of experimental materials such as Volborthite and Herbertsmithite that …
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Wonderland of frustration: Magnetic moments and itinerant electrons on the pyrochlore lattice
… range of intriguing quantum phenomena, including spin liquids, fractionalisation and long-range entanglement. In this thesis, we investigate the effects of frustration in magnetic systems on the pyrochlore lattice, looking at both the conventional frustrated magnetism as well as a less studied …
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Phases and phase transitions of strongly correlated electron systems
… fermion systems, which are correlated fermi liquids. In these systems, a lattice of localized electrons in f or d orbitals is coupled to the conduction electrons through an antiferromagnetic coupling. Singlets are formed between localized and conduction electrons. This singlet naturally have …
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Transport properties in the vicinity of Mott insulators
… values of U/t. In this regime, we study the spin liquid phase, a state that possibly lives between the Mott insulator and the normal metal. Motivated by the recently created organic compound r-(BEDT-TTF)2- Cu2(CN)3, we study a particular spin liquid where there is a spinon Fermi surface …
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Synthesis and characterization of single crystal kagomé lattice antiferromagnets
An ideal spin-% kagomé lattice has been a long sought material. This system is characterized by strong magnetic frustration and is a likely candidate for a spin-liquid ground state. The spin-liquid state was originally proposed to exist in the parent compounds of the high temperature …
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On numerical methods in quantum spin systems
… methods for studying quantum many- body spin systems. Part I sets the stage for research projects. In chapter 1, I go over major milestones in the field of frustrated magnetism, how it fits into a larger category of condensed matter physics, and recent developments that provide context …
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Interaction effects in topological insulators
… topological insulator and a strongly interacting spin liquid in its Majorana fermion representation. We use the Hartree-Fock mean-field approach, slave-rotor approach and slave-boson approach to study correlation effects related to topological insulators. With the spontaneous symmetry breaking …
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Density Matrix Renormalization Group Studies of Strongly Correlated Systems in Low Dimensions
… the electron systems in one dimension, and the spin systems in two dimension with large scale DMRG. For the Kondo lattice model we have found two charge-ordered phases in the doped regime which have not been found before. We also investigate the spin-$\frac{1}{2}$ XY model on the honeycomb …
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Ground states of a two-dimensional frustrated quantum antiferromagent Cs₂CuCl₄
… the candidates for materials with ground state spin liquid phase. The recent experimental results show that there exist several ground state phases in the presence of magnetic field which cannot be explained with classical Hamiltonian. In the thesis, I numerically studied the ground state of …
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Frustration from Frustration: Field Tuning, Vison Crystallisation, and Disorder in Quantum Spin Ice
Quantum spin ice (QSI) is one of the oldest and most widely known models of a U(1) quantum spin liquid – a fascinating phase of matter in which quantum electrodynamics emerges at low energies in a frustrated magnet. This playground for alternate-universe electromagnetism exhibits many phenomena …
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Slave particle study of the strongly correlated electrons
… his theory of phase transition, and Fermi liquids. The Landau theory of phase transition and the Fermi liquid theory together, can successfully explain a wide range of phenomena from ferromagnetism and antiferromagnetism to the conventional superconductivity. However, in the last thirty …
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Exotic phases and quantum criticality in gapless correlated electron systems
… field, can be addressed. Thirdly, in a quantum spin liquid phase that is likely to be realized in certain organic Mott insulators. Here we show how such a phase can be accessed from a low energy description of a metal, without resorting to slave-particle constructions. Methodologically, the work …
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Understanding, constructing, and probing highly-entangled phases of quantum matter
… on topics related to recently discovered quantum spin-liquid (QSL) materials. The possibility of a gapless QSL in the vicinity of the metal-insulator transition in doped semiconductors is explored, and optical conductivity is developed as an experimental tool to examine the nature of the QSL …
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