No description available.

Presented as Thesis (Ph. D.)--University of Wisconsin--Madison, 1935. / Title from added collective thesis t.p. Part 1 reprinted from Journal of the American Chemical Society, vol. 77 (1935) -- Part 2 reprinted from Physical review, vol. 48 (1 July 1935). eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Call number: LD2668 .T4 1952 W7 / Master of Science

LD2668 .T4 1949 W31 / Master of Science

The resonance frequency and the damping constant are interesting parametersrelated to the ferromagnetic spin resonance phenomenon. In this study theseparameters have been investigated for a number of Heusler multilayer film samplesusing a vector network analyzer ferromagnetic resonance setup. The complexsusceptibility of the samples is extracted from the transmittance scattering parameterS12 measured by the network vector analyzer. The ferromagnetic resonance ismirrored by a maximum in the imaginary part of the complex susceptibility. Theagreement between the theoretically calculated resonance frequency and theresonance frequency measured varied between samples. These differences originatefrom several sources, one of them is, the uncertainty in the internal magnetic field.This is due to irregularities and repeated interfaces between each layer in the Heuslersamples.

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains viii, 152 p. : ill. (some col.), maps. Includes abstract. Includes bibliographical references (p. 62-64).

The British Tertiary Volcanic Province comprises central volcanic complexes with positive gravity and magnetic anomalies, some centres associated with both large volumes of continental flood basalts and regional dyke swarms. The Lundy Island is the southern most expression of Tertiary volcanism and consists of granite intruded by around 200 dykes and associated with positive gravity and magnetic anomalies. The Lundy Dyke Swarm comprises basalt/dolerite and trachyte to rhyolite intrusions within host Tertiary granite (58.7 ± 1.6 Ma) and Devonian sediments. Outcrops of dykes are confined to coastal exposures on Lundy as they are veneered by peat over most of the island. Dykes present paired magnetic anomaly profiles, which allows their trends tobe determined by proton magnetometry. The dykes have a radial disposition superimposed on a ENE-WSW regional trend. Anisotropy of magnetic susceptibility studies indicate that magma for the radial component was emplaced at shallow to moderate inclinations, suggesting a relatively shallow origin near to the western border of Lundy Island. The regional component was emplaced at shallow to sub-horizontalangles, suggesting lateral movement of magma from a possible source 12 km to the northwest. Geochemical signatures indicate that the Lundy Dyke Swarm was transitional between plume-related magmatism and partial melting of the lithospheric mantle, the magma being stored in several small storage bodies at differing depths in the upper continental crust, rather than in one large magma chamber. Basic dykes at Lee Bay (60 ± 0.6 to 63.1 ± 0.7 Ma) pre-date the Lundy Dyke Swarm and were derived from a discrete magma chamber, possibly near to Morte Point. Conversely, other dykes in North Devon (Fremington dyke - 292.4 ± 1.7 Ma; Horse-Shoe Rocks - 339.6 ± 7.4 Ma) are not directly related to Tertiary magmatism, even though the Horse-Shoe Rocks have a Tertiary palaeomagnetic overprint. The Lundy Igneous Complex (comprising granite, dykes and sub-surface basic rocks) is situated close to the intersection of the Variscan Front and the Welsh Caledonides massif where the continental thickness is between 25 and 27 km. Emplacement of magma was assisted by the heavily fractured nature of the host sediments. However, a large positive gravity anomaly to the northwest of Lundy Island does not have a corresponding magnetic anomaly and so is interpreted as the response to relatively dense uplifted basement in the Lundy Horst rather than a large volume of basic rocks. Thus, the Lundy Igneous Complex probably did not produce sub-aerial volcanic activity, as pressure in the magma chamber would not have exceeded the overlying litho static load, despite the fractured nature of the host rocks.

No description available.

In this thesis the result x-ray diffraction, magnetic susceptibility, magnetization, and Mössbauer spectroscopy measurements of EuPdGe3, Al13Fe4, and FeNiSn are reported. The compound EuPdGe3 crystallizes in the BaNiSn3-type tetragonal structure (space group I4mm) with the lattice constants a = 4.4457(1) Å and c = 10.1703(2) Å. The results are consistent with EuPdGe3 being an antiferromagnet with the Néel temperature TN = 12.16(1) K and with the Eu spins S = 7/2 in the ab plane. The temperature dependence of the magnetic susceptibility above TN follows the modified Curie-Weiss law with the effective magnetic moment of 7.82(1) 𝜇𝐵 per Eu atom and the paramagnetic Curie temperature of −5.3(1) K indicative of dominant antiferromagnetic interactions. The M(H) isotherms for temperatures approaching TN from above are indicative of dynamical short-range antiferromagnetic ordering in the sample. The temperature dependence of the hyperfine magnetic field follows a S = 7/2 Brillouin function. The principal component of the electric field gradient tensor is shown to increase with decreasing temperature and is well described by a 𝑇32⁄ power-law relation. The Debye temperature of EuPdGe3 determined from the Mössbauer data is 199(2) K. The compound Al13Fe4 crystallizes in the monoclinic space group C2/m, in which Fe atoms are located at five inequivalent crystallographic sites, with the lattice parameters a = 15.503(2) Å, b = 8.063(2) Å, c = 12.464(2) Å, and β = 107.71(2)°. It is demonstrated that zero-field Mössbauer spectra can be decomposed into three quadrupole doublets. With the aid of the calculated electric field gradient (EFG) parameters we show that the first doublet results from one Fe site, the second doublet is due to two other Fe sites, and the third doublet originates from the last two Fe sites. We find that the shape of the Mössbauer spectrum of Al13Fe4 measured in an external magnetic field of 90 kOe can be accounted for with five component subspectra generated using the calculated II EFG parameters at five inequivalent Fe sites. The quadrupole splittings corresponding to three component doublets are shown to increase with decreasing temperature and are well described by a 𝑇32⁄ power-law relation. The Debye temperature of Al13Fe4 is found to be 383(3) K. We find a pseudogap in the density of states (DOS), with a width of ∼ 0.2 eV, that is centered 0.1 eV above the Fermi energy. The finite DOS at the Fermi energy confirms good metallicity of Al13Fe4. The 1/T-like dependence of the magnetic susceptibility shows that Al13Fe4 is a paramagnet. The compound FeNiSn crystallizes in the ZrBeSi-type crystal structure (space group P63/mmc) with the lattice constants a = 4.1329(1) Å and c = 5.1912(2) Å. It is a ferromagnet with the Curie temperature TC = 1024(10) K. Evidence is provided for a possible phase separation in the studied compound, into a majority magnetic phase and a minority, nanoscale, disordered phase with the corresponding iron magnetic moments at 4.6 K of 2.39(1) and 1.17(1) 𝜇𝐵. It is demonstrated that FeNiSn decomposes at a temperature significantly below TC when it is annealed in vacuum for about 30 hours. The Debye temperature of FeNiSn is found to be 445(6) K.

The entirety of the investigation discussed in this paper was confined to a study of the spin resonance properties of unpaired electrons of an organic free radical. In the remainder of the paper the theory of electron spin resonance, the apparatus used in the investigation, and the experimental results obtained are discussed in that order.