• Title/Summary/Keyword: 자기수축이방성

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Evolution of Magnetic Property in Ultra Thin NiFe Films (나노두께 퍼말로이에서의 계면효과에 의한 자기적 물성 변화)

  • Jung, Young-soon;Song, Oh-sung
    • Journal of the Korean Magnetics Society
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    • v.14 no.5
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    • pp.163-168
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    • 2004
  • We prepared ultra thin film structure of Si(100)/ $SiO_2$(200 nm)/Ta(5 nm)/Ni$_{80}$Fe$_{20/(l~15 nm)}$Ta(5 nm) using an inductively coupled plasma(ICP) helicon sputter. Magnetic properties and cross-sectional microstructures were investigated with a superconduction quantum interference device(SQUID) and a transmission electron microscope(TEM), respectively. We report that NiFe films of sub-3 nm thickness show the B$_{bulk}$ = 0 and B$_{surf}$=-3 ${\times}$ 10$^{-7}$(J/$m^2$). Moreover, Curie temperature may be lowered by decreasing thickness. Coercivity become larger as temperature decreased with 0.5 nm - thick Ta/NiFe interface intermixing. Our result implies that effective magnetic properties of magnetoelastic anisotropy, saturation magnetization, and coercivity may change abruptly in nano-thick films. Thus we should consider those abrupt changes in designing nano-devices such as MRAM applications.

A petrological study on the formation of geological heritage around Sangjogam County Park, Goseong, Gyeongsangnam-do (천연기념물 제411호 경남 고성 덕명리 공룡화석 산지 일원 병풍바위의 형성에 관한 암석학적 연구)

  • Kong, Dal-Yong;Cho, Hyeong-Seong;Kim, Jae-Hwan;Yu, Yeong-Wan;Jung, Seung-Ho;Kim, Tae-Hyeong;Kim, Jong-Sun;Jeong, Jong-Ok;Kim, Kun-Ki;Kwon, Chang-Woo;Son, Moon
    • Korean Journal of Heritage: History & Science
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    • v.51 no.2
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    • pp.78-91
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    • 2018
  • Sangjogam, located in Goseong, Gyeongsangnam-do, was designated as Natural Monument #411, because of its diverse geological heritage, such as fossils, ripple marks, dykes, and columnar joints. In the area, Byeongpungbawi, with its beautiful columnar joints vertical to the bedding plane of the underlying sedimentary rocks and spectacular coastal view, was named after its overall shape reminiscent of a huge folding screen. The purpose of this study was to investigate the formation process of the columnar joints using the anisotropy of magnetic susceptibility (AMS) method. AMS measurements showed that the k1 and k3 values representative of directions of the long and short axes of a magnetic particle at each point strongly clustered, and the oblate magnetic foliation structure in Byeongpungbawi developed during sill-type intrusion rather than lava flow. In summary, Byeongpungbawi was produced by sill-type intrusion along the bedding plane of the underlying sedimentary layer, and the subsequent formation of columnar joints was accompanied by the cooling and contraction of intruding rhyolite magma. This study potentially provides a basic research tool in understanding the formation mechanism of columnar joints which are widely distributed in southern Korea.