Resonance Position and Full Width Half Maximum in LSMO Thin Film Using FMR Technique

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2011-06-13
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This thesis determines the temperature dependence of the FMR spectra, the angular dependence of the FMR signal and the magnetic property (resonance position and full width half maximum) of the resonance field of a 15 uc thick LSMO thin film sample on a single crystalline SrTiO3 (STO) substrate at 150 K and 9.75 GHz using ferromagnetic resonance (FMR) technique. It was observed from the plot of the recorded signal versus the field (FMR spectra) at various temperatures (150 K, 200 K and 250 K) that as the temperature increases, the FMR spectra shifts to higher fields and this might be as a result of transition into the ferromagnetic state. The angular dependence of the FMR signal showed complicated phenomena at all temperatures and this might be due to the shape effects and other contributing factors such as misfit strain and crystal misfit in the LSMO thin film as discussed by other report. A plot of the resonance field versus the in-plane angle (when magnetic field is applied parallel to the thin film) showed a spectrum which was sinusoidal-like in nature with maximum and minimum curvatures. The resonance position and the full width half maximum (FWHM) of the 15 uc thick LSMO thin film sample were 1070.1875 Oe and 159.3125 Oe respectively. Ferromagnetic resonance (FMR) has also been observed in various unit cells of LSMO thin film for both simple width and simple position at 150 K and this observation of FMR has been used to confirm in-plane anisotropy of magnetic properties of LSMO/STO substrate which is as a result of distribution of anisotropies in the film. The 15 uc thick LSMO thin film displayed ferromagnetic resonance at 200 K and 250 K and this has also been confirmed by the surface plots.
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A Thesis Submitted to the Department of Physics, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirement for a degree of Master of Science in Solid State Physics, July-2011
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