STUDY OF SUPER-THIN FILMS DEPOSITED ON SEMICONDUCTOR-SUBSTRATES BY BRILLOUIN SPECTROSCOPY OF SURFACE WAVES

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The objective of this research project is the construction of a high performance Brillouin spectrometer and studies of super-thin films and multi-layer films grown on semiconductor substrates by using this spectrometer. The obtained results in these three years (1987-1990) is summarized as follows:1. We have developed a high performance tandem 5-pass Fabry-Perot interferometer, which can measure the Brillouin spectra of acoustic and spin waves in opaque metallic films. New attempts are made on the optics, the method of multi-pass system, the piezo-ceramic elements for fine controlling of the Fabry-Perot mirrors, and the electrical circuits. The constructed interferometer show high stability and is easy to treat even for a beginner of the spectroscopic measurements. Further antivibration table are introduced to eliminate the vibration from outside. As a result, it has been possible to make detailed Brillouin study of the metallic thin films.2. Brillouin studies have been made on the Co- … More Au-Co and Co-Nb-Co triple-layered films deposited on Si substrates. The exchange interaction between the Co layers through the nonmagnetic-metal layer is investigated, which is larger in case of the Au layer than in the Nb-layer case due to the difference of the electron density.The spin wave spectra are also measured in multi-layered films of Tb-(Fe,Co), which is fabricated for the vertical magnetic recording media. Broad asymmetric spin-wave spectra have been observed. These are composed of the multi-mode spin waves in the multi-layered structure. Quantitative interpretation has been made on the multi-mode spin wave spectra.3. Co-Pt alloy films for the horizontal magnetic recording media are prepared by sputtering. The spin wave spectra are investigated as a function of the alloy composition. The spin wave spectra in these alloy films are remarkably broadened, which is caused by the crystal grain structure of the alloy films. To elucidate the role of Pt which separates the magnetic Co-grains, the exchange interaction of the Co double-layers with the Pt interlayer has been measured. From these results, optimum conditions are studied on the alloy composition and the grain structure for the high-density magnetic recording media. Less