Phase-resolved Spin-Wave Tomography

The propagation dynamics of spin waves are represented by their dispersion relations. Recently, we have developed a method, called spin-wave tomography (SWaT), to obtain dispersion relation of spin waves in the long wavelength regime, so-called pure magnetostatic waves. In our previous studies on SWaT, phase information of spin waves was disregarded. In this report, we demonstrate an advanced SWaT analysis, called phase-resolved spin-wave tomography (PSWaT), to realize the direct observation of the amplitude and the phase of spin waves. The PSWaT spectra are obtained by separating the real and the imaginary components of the complex Fourier transform in the SWaT analysis. We demonstrate the PSWaT spectra of spin waves excited by the photo-induced demagnetization in a Bi-doped garnet film, reflecting the characteristic features of the complex dynamical susceptibility affected by magnetostatic coupling in the film.Comment: 5 pages, 4 figure

Recital: Eiji Hashimoto, Harpsichord; November 20, 1974

Hayden AuditoriumWednesday EveningNovember 20, 19748:15 p.m

Frequency and wavenumber selective excitation of spin waves through coherent energy transfer from elastic waves

Using spin-wave tomography (SWaT), we have investigated the excitation and the propagation dynamics of optically-excited magnetoelastic waves, i.e. hybridized modes of spin waves and elastic waves, in a garnet film. By using time-resolved SWaT, we reveal the excitation dynamics of magnetoelastic waves through coherent-energy transfer between optically-excited pure-elastic waves and spin waves via magnetoelastic coupling. This process realizes frequency and wavenumber selective excitation of spin waves at the crossing of the dispersion relations of spin waves and elastic waves. Finally, we demonstrate that the excitation mechanism of the optically-excited pure-elastic waves, which are the source of the observed magnetoelastic waves, is dissipative in nature.Comment: 5 pages, 4 figure

180-degree phase shift of magnetoelastic waves observed by phase-resolved spin-wave tomography

We have investigated optically-excited magnetoelastic waves by phase-resolved spin-wave tomography (PSWaT). PSWaT reconstructs dispersion relation of spin waves together with their phase information by using time-resolved magneto-optical imaging for spin-wave propagation followed by an analysis based on the convolution theorem and a complex Fourier transform. In PSWaT spectra for a Bi-doped garnet film, we found a 180 degree phase shift of magnetoelastic waves at around the crossing of the dispersion relations of spin and elastic waves. The result is explained by a coupling between spin waves and elastic waves through magnetoelastic interaction. We also propose an efficient way for phase manipulation of magnetoelastic waves by rotating the orientation of magnetization less than 10 degree.Comment: 5 pages, 4 figure

トショ ショウカイ ウォーレン バックランド チョ マエダ シゲル カナメ マリコ ヤク フィルムスタディーズ ニュウモン

ウォーレン・バックランド著　前田茂・要真理子訳 『フィルムスタディーズ入門』 晃洋書房　200

セイカツ シュウカンビョウ オ ヨボウ スル タメ ノ ショクジ リョウホウ : メタボリック シンドローム タイサク

Recently, the number of cases of lifestyle-related diseases including obesity, dyslipidemia, heart disease, hypertension and type２diabetes has been steadily increasing due to an excess energy intake because of the westernization of eating habits, unbalanced diet, irregular lifestyle and lack of exercise. Obesity with accumulation of visceral fat causes metabolic syndrome which can leads to glucose intolerance, disorder of lipid metabolism, high blood pressure and so on. Metabolic syndrome has become a serious cause of the onset of arteriosclerosis. The improvement of lifestyle through diet and exercise therapy is important and effective prevent arteriosclerosis