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 23 for “"Ferromagnetic Phase"”.
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Ultracold Fermi gas with repulsive interactions
… good agreement with a mean-field model for the ferromagnetic phase transition. However, later research showed the absence of enhanced spin fluctuation, which is definitive evidence against the ferromagnetic phase transition. Still, our work triggered a lot of research on repulsive interactions …
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Ground states of a two-dimensional frustrated quantum antiferromagent Cs₂CuCl₄
… 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 Cs₂CuCl₄ using …
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A Micromechanics Study on Ferroelectrics and Multiferroic Composites
… the shape, size and the distribution; the phase connectivity; and the loading conditions will impact the results. First, we focus on the investigation of ferroelectrics and its composites. Based on the experimental observations, the nonlinear electromechanical coupling responses of …
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Study of localization and correlation effects in disordered electronic systems
… 3 describes a study of the disordered-antiferromagnetic instability in a lattice system with a half-filled band using exact eigenstates of the noninteracting part of the Hamiltonian. The phase diagram for the 1 -d and 3 -d systems has been obtained. The interacting fixed point which …
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Ferromagnetism and transport in diluted magnetic semiconductors
… affect the charge transport properties in the ferromagnetic phase. We show that non-local correlations, within the DCA, are responsible for magnetic frustration and magnetic reorientation of the DMS. The DMFA is employed to study ferromagnetism and transport in Ga<sub>1-x</sub>Mn<sub>x</sub>As, …
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Aspects of Quantum Fluctuations under Time-dependent External Influences
… Finally, we consider dynamic quantum phase transitions in the last part of this Thesis. To this end two specific scenarios will be investigated: firstly, the structure formation during the superfluid to Mott-insulator transition in the Bose-Hubbard model; and secondly, the formation of …
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Factors affecting the magnetic properties of alloys fine dispersions of cobalt.
… are due to the presence of a finely divided ferromagnetic phase which, in some cases, contains a substantial proportion of cobalt. The most important examples are the alnico alloys, deriving permanent magnet properties from a fine dispersion of a ferromagnetic, b.c.c. phase rich in cobalt and …
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Dipolar Interactions, Long Range Order and Random Fields in a Single Molecule Magnet, Mn12-acetate
… Weiss temperature), implying the existence of a ferromagnetic phase at low temperature.</p> <p>Applying a magnetic field in the transverse direction moves the Weiss temperature downward towards zero. This implies that the transverse field triggers mechanisms in the system that compete with the …
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Fluctuations and state preparation in quantum degenerate gases of sodium and lithium
… predictions, this system does not undergo a ferromagnetic phase transition. The second part describes the development of an apparatus for performing experiments with sodium and lithium in optical lattices. We describe progress towards the implementation of synthetic magnetic fields in systems …
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Studies in random Ising spin systems
… are two different critical behaviors along the ferromagnetic phase boundary. McMillan's domain-wall renormalization group is applied to the three -dimensional random-field Ising model. Numerical results show that the critical behavior of this model is controlled by a fixed point at zero …
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Raman scattering in heavy rare earth metals
… orthorhombic distortion of the lattice in the ferromagnetic phase. The ferromagnetic acoustic spin wave gap in Dy was observed. To our knowledge this is the first observation of a metallic spin wave by Raman scattering. The light scattering measurement of the spin wave gap energy agrees with …
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1/F Noise & slow spin dynamics in chromium, chromium alloys, and disordered iron zirconium
… which were found in the incommensurate SDW phase were absent in the commensurate phase. This absence indicates that incommensurability plays a crucial role in the polarization domain dynamics. Amorphous FeZr undergoes two magnetic phase transitions which were studied using 1 If noise. The …
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Application Of Scanning Hall Probe Microscopy For High Throughput Characterization Of Combinatorial Magnetic Materials
… magnetic fields. Specifically, we have studied phase diagrams of Co-Fe-Ni binary and ternary alloys, as well as weak itinerant ferromagnet MnSi. The Co-Fe-Ni alloys were fabricated by annealing three metal blocks placed in intimate contact at high temperatures to allow thermal interdiffusion to …
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Structural, electro-magnetic and electrical analysis in monovalent doped Nd0.75Na0.25-xKxMnO3 manganites
… investigated to study its effect on crystalline phase and surface morphology as well as electrical transport and magnetic properties. However most of study show inconsistent result regarding to the electrical transport and magnetic properties as well as crystalline phase and morphology study. …
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Understanding and Controlling the Magnetic and Optical Properties in van der Waals Semiconductors
… intriguing potential for manipulating magnetic phases in 2D magnets through interfacial charge transfer in heterostructures of magnetic and nonmagnetic layers.4 We unveil a transition towards the ferromagnetic phase by stacking antiferromagnetic bilayer CrSBr on graphene and by electrostatic …
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Strongly correlated ultra-cold bosonic atoms in optical lattices
… physics is to study the origin of exotic quantum phases such as coexistent and inhomogeneous phases, quantum criticality, and secondary ordered phases close to quantum critical points. Exotic phenomena in strongly correlated systems occur due to competing complex interactions of spin, charge, …
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Electrical injection and detection of spin polarization in InSb/ferromagnet nanostructures
… and strong spin-orbit interaction. Using ferromagnetic CoFe, lateral InSb/CoFe devices are fabricated by semiconductor processing techniques. The saturation magnetizations of various CoFe electrodes with different widths are calculated from Hall measurements in which the fringing fields of …
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Phase Field Crystal Approach to the Solidification of Ferromagnetic Materials
… field theoretical approach, called the Magnetic Phase Field Crystal model. We constructed the free energy by extending the Phase Field Crystal (PFC) formalism and including terms to incorporate the ferromagnetic phase transition and the anisotropic magneto-elastic effects, i.e., the …
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Two phase magnetoelectric epitaxial composite thin films
… Magnetoelectricity can be found both in single phase and composite materials. Compared with single phase multiferroic materials, composite multiferroics have higher ME effects. Through a strictive interaction between the piezoelectricity of the ferroelectric phase and the magnetostriction of the …
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