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 59 for “"Antiferromagnet"”.
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Neutron scattering and magnetization studies of the spin correlations on the kagomé lattice antiferromagnet KFe₃(Oh)₆(SO₄)₂
(cont.) The former represents a continuous planar rotational symmetry corresponding to the SO(2) symmetry, while the latter is a discrete symmetry associated with the Z2 symmetry. Depending on which measurements are performed, the critical behavior of the system can belong to either SO(2) or Z2 …
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Thermodynamic and neutron scattering study of the spin- 1/2 kagome antiferromagnet ZnCu₃(OH)₆Cl₂ : a quantum spin liquid system
… to look for such an exotic state in the form of antiferromagnetic Cu2+ kagome planes. The x = 1 end member, named herbertsmithite, has shown promising spin liquid properties from prior studies on powder samples. Here we show a new synthesis by which high-quality centimeter-sized single crystals …
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The ground state of the spin-1/2 kagomé lattice antiferromagnet : neutron scattering studies of the zinc-paratacamite mineral family
… the ground state of the spin-1 2 kagomé lattice antiferromagnet, as such a system is considered ideal for the emergence of spin liquid physics. Clinoatacamite, a distorted kagomé lattice antiferromagnet with weak inter-plane coupling, undergoes a Néel or- dering transition at TN ~/~ 6.2 K and …
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Magnetoresistance effects in metallic antiferromagnets
Antiferromagnets are drawing significant interest as alternatives to ferromagnets in designing faster and more robust memory devices. Recent theoretical and experimental advances show that antiferromagnets can be readily detected and manipulated owing to their diverse crystal and magnetic …
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Ultrafast Spin-Charge Conversion Schemes in Magnets: THz Time Domain Spectroscopy Study
… unreported spin current enhancement in the antiferromagnet-ferromagnet mixed phase state at low temperatures and propose potential mechanisms responsible for it. Finally, we report the generation of helicity-dependent ultrafast photocurrents in a noncollinear antiferromagnet Mn3Sn. We …
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Cation Site Occupancy and Defect Engineering in Perovskite Heterostructures
… with the generation of ferroelectricity in an antiferromagnet LuFeO₃ through cation antisite defects and concomitant inversion symmetry breaking. We elucidate how the crystal structure and ferroelectricity depend on cation stoichiometry. We then integrate this antiferromagnet into a …
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Ground states of a two-dimensional frustrated quantum antiferromagent Cs₂CuCl₄
The properties of a frustrated quantum antiferromagnet are interesting topics in condensed matter theory. Among the quantum antiferromagnets, Cs₂CuCl₄ gains attention as one of the candidates for materials with ground state spin liquid phase. The recent experimental results show that there exist …
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Study of the training effect in exchange bias using the domain state model
… analysis was developed for the study of the antiferromagnet during consecutive hysteresis loops. A special focus was given to the response of training effect on temperature. Several characteristics of the system were varied to investigate the physics of the training effect, such as the …
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One-dimensional bosonization approach to higher dimensions
… dissertation is devoted to quasi-one dimensional antiferromagnetic lattices. A spatially anisotropic lattice antiferromagnet can be viewed as an array of one dimensional spin chains coupled in a way to match the lattice symmetry. This allows to use the non-Abelian bosonization technique to …
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Fundamentals, Voltage Control and Novel Application of Exchange Bias in Magnetic Thin Films
… EB is an effect that arises at ferromagnet/antiferromagnet interfaces, which imposes an internal field on the ferromagnet, enhancing the range of functionalities that can be derived from devices. This thesis explores EB in Co/Co₁₋ₓNiₓO systems at multiple levels, from fundamental …
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Field theoretical methods for strongly correlated electron systems
… approach to investigate the Frustrated Quantum Antiferromagnet. We study the Chiral Spin Liquid state of the antiferromagnet at zerotemperature, which has a spin-gap generated by the spontaneous breakdown of time-reversalsymmetry. This state is known as the Chiral Spin State. We determine …
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Ultrafast Terahertz Spectroscopy for the Manipulation and Elucidation of Correlated Quantum Materials
… the collective modes of two van der Waals antiferromagnets are excited coherently with the use of ultrafast optical pulses. In the antiferromagnet NiPS3 a new mechanism for launching a coherent magnon is discovered. In the multiferroic, antiferromagnet NiI2, evidence for a new type of …
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X-ray and neutron scattering studies of the Rb₂MnF₄ and Cu₁âõxMgx̳GeO₃ in an external magnetic field
… ideal two-dimensional square lattice Heisenberg antiferromagnet with S = 5/2. When this material is placed in a magnetic field on an extrapolation of the spin-flop phase boundary into the paramagnetic phase, Heisenberg critical behavior can be accessed to a much longer correlation length than had …
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Antiferromagnetism, ferromagnetism and magnetic phase separation in Bi₂Sr₂O₆â[delta]
… and therefore contain mostly Co3+ ions, enter an antiferromagnetic (AF) phase with a Neel temperature - 250 K. On the other hand, annealing as-grown crystals in vacuum to reach [delta approx.] 0.25 destroys the AF phase; these samples exhibit predominantly ferromagnetic (FM) behavior with Tc …
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Magnetische, thermische und dielektrische Stabilität von magnetischen Tunnelelementen
… Tunnelelementen ein sogenannter künstlicher Antiferromagnet (Artificial Antiferromagnet, AAF) verwendet (Co/Cu/Co oder CoFe/Ru/CoFe). Die Motivation für die durchgeführten Untersuchungen ist aus Sicht der potentiellen Anwendung offensichtlich: Die MRAM-Technologie muss kompatibel zur …
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Magnetic ordering and spin wave dynamics in transition metal arsenides
… orbit torque based switching was proposed in antiferromagnets, there is a growing interest in using a metallic antiferromagnet as an active component of a spintronic device. Arsenic forms a large pool of magnetic metals in combination with transition metal atoms. In this report, we explore …
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The Influence of Defects on the Vibrational and Electronic Properties of the Quasi 1D van der Waals Magnet CrSBr
… defect engineering. The 2D semiconducting antiferromagnet CrSBr has generated recent attention because of its correlated magnetic, optical, and electronic properties, air stability, and quasi-1D electronic structure. In this thesis, we implement resonant Raman spectroscopy to explore the …
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Topological Transport Effects and Pure Spin Currents in Nanostructures
… the transport response is consistent with the antiferromagnetic spin Seebeck effect mediated by the small magnetic field induced magnetization also reported for other antiferromagnet/metal heterostructures. As such, we cannot verify the presence of a spin superfluid ground state in the system. …
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Probing two-dimensional magnetic phenomena with diamond quantum microscopy
… Two-dimensional van der Waals magnets and antiferromagnets are emerging material platforms that have recently gained popularity but still lack a complete understanding of their underlying mechanisms. In particular, the low magnetic signal poses a significant limitation to real-space …
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Quantum Tuning and Emergent Phases in Charge and Spin Ordered Materials
… it. The Néel Temperature of the two-dimensional antiferromagnet FePS$_3$ was found to increase linearly with applied hydrostatic pressure. Evidence of an insulator-metal transition is also presented, and an unexplained upturn in the resistivity at low temperatures in the metallic phase.
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