• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.174-174
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• 2000

A strong antiferromagnetic coupling in Fe/Si multilayered films (MLF) had been recently discovered and much consideration has been given to whether the coupling in the Fe/Si MLF system has the same origin as the metal/metal MLF. Nevertheless, the nature of the interfacial ron silicide is still controversial. On one hand, a metal/ semiconductor structure was suggested with a narrow band-gap semiconducting $\varepsilon$-FeSi spacer that mediates the coupling. However, some features show that the nature of coupling can be well understood in terms of the conventional metal/metal multilayered system. It is well known that both magneto-optical (MO) and optical properties of a metal depend strongly on their electronic structure that is also correlated with the atomic and chemical ordering. In this study, the nature of the interfacial regions is the Fe/Si multilayers has been investigated by the experimental and computer-simulated MO and optical spectroscopies. The Fe/Si MLF were prepared by rf-sputtering onto glass substrates at room temperature with the number of repetition N=50. The thickness of Fe sublayer was fixed at 3.0nm while the Si sublayer thickness was varied from 1.0 to 2.0 nm. The topmost layer of all the Fe/Si MLF is Fe. In order to carry out the computer simulations, the information on the MO and optical parameters of the materials that may constitute a real multilayered structure should be known in advance. For this purpose, we also prepared Fe, Si, FeSi2 and FeSi samples. The structural characterization of Fe/Si MLF was performed by low- and high -angle x-ray diffraction with a Cu-K$\alpha$ radiation and by transmission electron microscopy. A bulk $\varepsilon$-FeSi was also investigated. The MO and optical properties were measured at room temperature in the 1.0-4.7 eV energy range. The theoretical simulations of MO and optical properties for the Fe/Si MLF were performed by solving exactly a multireflection problem using the scattering matrix approach assuming various stoichiometries of a nonmagnetic spacer separating the antiferromagnetically coupled Fe layers. The simulated spectra of a model structure of FeSi2 or $\varepsilon$-FeSi as the spacer turned out to fail in explaining the experimental spectra of the Fe/Si MLF in both intensity and shape. Thus, the decisive disagreement between experimental and simulated MO and optical properties ruled out the hypothesis of FeSi2 and $\varepsilon$-FeSi as the nonmagnetic spacer. By supposing the spontaneous formation of a metallic ζ-FeSi, a reasonable agreement between experimental and simulated MO and optical spectra was obtained.

• 문화기술의 융합
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• 제9권5호
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• pp.493-499
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• 2023

신용거래(Trade Credit)는 제품 공급자가 중간유통자에게 제품 구입비용에 대하여 일정 기간 동안 지불 유예를 허용하는 거래 행위로 일반적으로 경쟁 기업과의 차별화 수단으로 허용되어 진다. 이와 같은 신용 거래는 고객의 거래량(주문량 크기) 증대를 목적으로 거래량의 크기에 따라 종속적으로 허용되는 것을 흔히 볼 수 있다. 또한 중간유통자 입장에서 보면 신용거래가 허용되면, 제품 구입비용에 대하여 일정 기간 동안의 지불 유예가 가능하여 재고투자비용의 절감 효과를 기대할 수 있고, 이와 같은 재고 투자비용의 절감은 최종 고객의 수요를 늘릴 수단으로 판매가격을 할인하는 요인이 될 수 있다. 본 연구에서는 공급자가 중간유통자의 거래량에 종속적으로 지불 유예 기간을 허용하는 상황 하에서 최종고객의 연간 수요가 중간유통자의 판매가격에 지수적으로 감소하는 가격탄력함수(a price elasticity function)의 경우를 고려하여 중간유통자 관점의 최적 판매가격과 주문량을 결정하는 모형을 분석하고자 한다. 문제 분석을 위하여 제품은 시간이 경과함에 따라 일정율로 퇴화하는 경우에 중간유통자의 재고 모형을 수립하고, 퇴화가 중간유통자의 재고 정책에 미치는 영향에 대해서 분석 해 보고자 한다.