• 제목/요약/키워드: spintronics

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Spintronics Devices for Bio-medical Applications

  • Lim, Byeonghwa;Hu, Xinghao;Torati, Sri Ramulu;Kim, Kun Woo;Yoon, Jonghwan;Kim, Cheol Gi
    • 한국자기학회:학술대회 개요집
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    • 한국자기학회 2017년도 임시총회 및 하계학술연구발표회
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    • pp.28-29
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    • 2017
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Width-Dependent Transition of Magnetic Domain Configuration in Nanostructured CoFe/Pt Multilayered Nanowires

  • Je, Soong-Geun;Lee, Jae-Chul;Kim, Kab-Jin;Min, Byoung-Chul;Shin, Kyung-Ho;Choe, Sug-Bong
    • Journal of Magnetics
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    • 제17권4호
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    • pp.242-244
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    • 2012
  • We report on the basis of experiments that magnetic domain structures exhibit a transition between single and dendrite domains with respect to the width of ferromagnetic nanowires. This transition is directly observed in CoFe/Pt multilayered nanowires having a width in the range of 580 nm to 4.2 ${\mu}m$ with a magnetic force microscope. Nanowires wider than 1.5 ${\mu}m$ show typical dendrite domain patterns, whereas the nanowires narrower than 690 nm exhibit single domain patterns. The transition occurs gradually between these widths, which are similar to the typical widths of the dendrite domains. Such a transition affects the strength of the domain wall propagation field; this finding was made by using a time-resolved magneto-optical Kerr effect microscope, and shows that the domain wall dynamics also exhibit a transition in accordance with the domain configuration.

Hysteresis Loops of Magnetically Coupled Multilayers - Experiment and Calculations

  • Czapkiewicz, M.;Stobiecki, T.;Rak, R.;Wrona, J.;Kim, C.G.
    • Journal of Magnetics
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    • 제9권2호
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    • pp.60-64
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    • 2004
  • In this paper calculations of magnetisation and magnetoresistance characteristics of the Spin Valve (SV) and Pseudo Spin Valve (PSV) spintronics structures are reported and compared with the experimental data. The magnetisation reversal process was analysed with respect to the Stoner- Wohlfahrt model of total surface energy in terms of uniaxial anisotropy, exchange coupling between ferromagnetic layers, unidirectional exchange anisotropy of pinned layer (modelled by exchange coupling between magnetisation of pinned layer and net magnetisation of antiferromagnetic layer with high anisotropy). The numerical simulation of the model to the experimental magnetisation data yielded the above parameters for SV and PSV structures. These parameters were used to more sophistically micromagnetic modelling tool originating from the project called Object Oriented Micromagnetic Framework. Influence of the shape anisotropy of the Magnetic Tunnelling Junction cell used in MRAM was simulated by means of micromagnetic simulations. Results were compared to those obtained from the spot Kerr measurements.

GaMnAs 자성반도체의 박막 특성 및 후처리에 따른 특성 변화 연구 (A Study on the Properties of the Magnetic Semiconductor GaMnAs Depending on Thin Film Deposition and the Treatment Conditions)

  • 김동식
    • 전자공학회논문지 IE
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    • 제45권3호
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    • pp.1-4
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    • 2008
  • 본 연구에서는 비약적으로 발전하고 있는 반도체 소자가 요구하는 새로운 특성을 가진 신소재의 개발에 부응하여, 최근 세계적으로 많은 연구가 되고 있는 spintronics에 사용되는 화합물 자성반도체 박막에 관한 연구를 수행하였다. 본 연구에서 사용되는 GaMnAs 자성반도체 박막은 기존의 III-V족 화합물 반도체 소자에 적용이 쉽고, 그 응용범위가 넓어 앞으로의 전망이 매우 밝은 새로운 화합물 반도체라고 할 수 있다. 그러나 이런 GaMnAs 자성반도체 박막의 경우 현재까지 자성 특성을 나타내는 Curie 온도가 매우 저온에서만 나타나며, 또한 성장 조건에 따라 그 특성이 매우 달라지는 문제점을 가지고 있다. 따라서 본 논문에서는 GaMnAs 자성반도체 박막을 성장시키기 위한 최적조건과 자성특성을 향상시키기 위한 실험을 수행하였다.

Bonding And Anti-bonding Nature of Magnetic Semiconductor Thin Film of Fe(TCNQ:tetracyanoquinodimethane)

  • Jo, Junhyeon;Jin, Mi-jin;Park, Jungmin;Modepalli, Vijayakumar;Yoo, Jung-Woo
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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    • pp.294-294
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    • 2014
  • Developing magnetic thin films with desirable physical properties is a key step to promote research in spintronics. Organic-based magnetic material is a relatively new kind of materials which has magnetic properties in a molecular and microscopic level. These materials have been constructed by the coordination between 3d transition metal and organic materials producing long-range magnetic orders with a relatively high transition temperature. However, these materials were mostly synthesized as a form of powder, which is difficult to study for their physical properties as well as apply for electronic/spintronic devices. In this study, we have employed physical vapor deposition (PVD) to develop a new organic-based hybrid magnetic film that is achieved by the coordination of Fe and tetracyanoquinodimethane (TCNQ). The IR spectra of the grown film show modified CN vibration modes in TCNQ, which suggest a strong bonding between Fe and TCNQ. The thin film has both ferromagnetic and semiconducting behaviors, which is suitable for molecular spintronic applications. The high resolution photoemission (HRPES) spectra also show shift of 1s peak point of nitrogen and the carbon 1s peaks display traces of charge transfer from Fe to TCNQ as well as shake-up features, which suggest strong bonding and anti-bonding nature of coordination between Fe and TCNQ.

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