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 15 of 15 for “"Spin density wave"”.
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1/F Noise & slow spin dynamics in chromium, chromium alloys, and disordered iron zirconium
1/f resistance noise studies of the spin dynamics in two magnetic systems are described in this thesis. In chromium, 1 If noise was used as a probe to study spin density wave polarization dynamics. Measurements of the noise anisotropy in a high quality single crystal of Cr revealed a temperature …
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Magnetic properties of the rare earth systems neodymium/yttrium and dysprosium/yttrium
… for the first time, the presence of the induced spin-density wave in the conduction band of nonmagnetic Lu atoms which are alloyed in a helimagnetic Dy host lattice. By tuning the incident synchrotron x-ray energy to the L$\rm\sb{III}$ edges of both Dy and Lu, we were able to use the …
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Phase diagram for the S equals one-half and J equals three-halves Kondo lattice model
… include antiferromagnetism, ferromagnetism, and spin-density wave ordering of both commensurate and incommensurate varieties. In S=1/2, the magnetic phase exhibits a spike in critical temperature at half-filling. In J=3/2, the Kondo phase is reentrant at weaker coupling but not at stronger …
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Penetration Depth Studies of Unconventional Superconductors
… borocarbides RENi2B2C (RE = Y, Lu, Er, Ho), the spin-triplet superconductor Sr2RuO4, and elemental Pb. From these studies we see how superconductivity is affected by the presence of another order, such as paramagnetism/antiferromagnetism (in ErNi2B2C) or spin-density-wave (in Pb). We also see how …
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Magnetische Strukturen in [Er/Tb]-Schichtsystemen : Einfluss der magnetischen Nachbarschaft und konkurrierender Anisotropien
… localized 4f states can be related to a coherent spin density wave in the conduction bands of both Er and Tb. The direct observation of spin density wave was made possible only by the improvements of the RXMS technique, i.e., an excellent source at the beamline 6id-b of the APS at the Argonne …
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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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Computational Studies of Correlated Electrons in One-Dimension
… construction of ""operator-loop"" updates for spin-1/2 fermions and the inclusion of electron-phonon interactions in the Stochastic Series Expansion Quantum Monte Carlo method and the use of Quantum Parallel Tempering to improve the quality of the numerical data. For the extended Hubbard model …
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Applied fractionalization : quantum phases and phase transitions of strongly interacting systems
… transitions very different from the conventional spin-density wave instability of Fermi surface.
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Search, Discovery, Synthesis and Characterization of Itinerant Magnets Composed of Non-magnetic Constituents
… and magnetism, metamagnetic transitions, spin- and cluster-glass behavior, multisublattice magnetism, non-Fermi liquid behavior, and quantum criticality. Surprisingly, while many systems exhibit both local and itinerant magnetism, only two are known to contain no local moment ions: Sc3In …
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Quantum many body physics in single and bilayer graphene
… collective phenomena. However, the vanishing density of states in charge neutral single layer graphene suppresses many body effects, and one has to alter the system to observe strongly ordered states. We consider three ways of accessing quantum many body physics using graphene. First, we …
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Non-equilibrium dynamics of dipole-coupled internal states in cold gases
… which results in the systems studied behaving as spin$-1/2$ models with long-range interactions. We first study a closed system with both static and resonant near-field dipole interactions under an external drive. By studying the uniform mean-field dynamics of the system, we find the dynamics are …
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Topics in Spin-Orbit Coupling in Cold Atoms and Semiconductors
… contains a collection of topics on the spin-orbit coupling of cold atoms and semiconductors. We first consider the effects of an optically induced spin-orbit interaction on a system of Bosonic atoms. The spin-orbit term couples the emergent pseudo-spin- 1/2 degree of freedom to momentum. …
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Electronic structure and energetics of Fe-based superconductors: Effects of chemical and magnetic disorder in (Ba-X)(Fe-Y)2As2
… all implemented within a self-consistent-field, density functional theory (DFT). For $Tm$ doping, we detail the Fermi-surface evolution and nesting that dictate instabilities to the observed spin-density wave (SDW) state. For Am doping we track topological changes in the Fermi surface and connect …
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Syntheses, Characterizations, and Properties of Suboxides and Layered Titanium-based Pnictide Oxide Superconductors
… (at Tc = 54 K) that can be attributed to spin density wave (SDW) or charge density wave (CDW) transitions. This is reminiscent of the un-doped phases of the FeAs-based high-Tc superconductors. Chemical substitution experiments were performed for the purpose of suppressing the magnetic …
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Coupled one dimensional electron systems and stripe phases of high temperature superconductors
… chapter one, I consider the problem of the Local Density of States for spin-gapped one-dimensional charge density wave (CDW) states and Mott insulators in the presence of a hard-wall boundary. I calculate the boundary contribution to the single-particle Green function in the low-energy limit using …