• Title/Summary/Keyword: pseudo-gap

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Critical review of pseudo-gap in high Tc superconductors : Experiments and theories

  • Choi, Han-Yong
    • 한국초전도학회:학술대회논문집
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    • v.10
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    • pp.8-8
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    • 2000
  • Recently the study of the pseudo-gap in high temperature superconductivity become critical issue because it contains key information of the pair formation of the high temperature superconductivity. Specially angle resolved photoemission study shows the various information of the gap formation. In this talk, I will review the recent theories as will as experiments on the pseudo-gap in high temperature superconductors. Specially I will introduce the possible observation of the Andreeve reflection in the underdopped high temperature superconductors.

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Annealing condition dependence of the superconducting property and the pseudo-gap in the protect-annealed electron-doped cuprates

  • Jung, Woobeen;Song, Dongjoon;Cho, Su Hyun;Kim, Changyoung;Park, Seung Ryong
    • Progress in Superconductivity and Cryogenics
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    • v.18 no.2
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    • pp.14-17
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    • 2016
  • Annealing as-grown electron-doped cuprates under a low oxygen-partial-pressure condition is a necessary step to achieve superconductivity. It has been recently found that the so-called protect annealing results in much better superconducting properties in terms of the superconducting transition temperature and volume fraction. In this article, we report on angle-resolved photoemission spectroscopy studies of a protect-annealed electron-doped cuprate $Pr_{0.9}La_{1.0}Ce_{0.1}CuO_4$ on annealing condition dependent superconducting and pseudo-gap properties. Remarkably, we found that the one showing a better superconducting property possesses almost no pseudo-gap while others have strong pseudo-gap feature due to an anti-ferromagnetic order.

Temperature Dependent Angle Resolved Photoemission Spectroscopy Study of Pseudo-gaps in $Sm_{1.82}Ce_{0.18}CuO_4$ (각분해 광전자분석 실험을 이용한 $Sm_{1.82}Ce_{0.18}CuO_4$ 물질의 온도에 따른 가짜 갭 연구)

  • Song, D.J.;Choi, H.Y.;Kim, Chul;Park, S.R.;Kim, C.;Eisaki, H.
    • Progress in Superconductivity
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    • v.11 no.2
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    • pp.83-86
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    • 2010
  • There are theoretical and experimental evidences for the pseudo-gap in electron doped cuprates being due to interaction between electrons and anti-ferromagnetism(AFM). A remaining issue is on how AFM correlates with pseudo-gap, and eventually with superconductivity. To elucidate the issue, we have performed temperature dependent angle-resolved photoemission studies of an e-doped cuprate superconductor $Sm_{2-x}Ce_xCuO_4$(SCCO) x=0.18 at 20K and 150K. In the case of $Nd_{2-x}Ce_xCuO_4$, the most well known e-doped cuprate, pseudo-gap disappears at around 100 K for x=0.17. Our experimental result reveals that the pseudo-gap of SCCO exists even at 150K for x=0.18. This result implies that the AFM of SCCO survives even in x=0.18, which agrees with previously reported phase diagram of SCCO. Yet, the superconductivity disappears around x=0.18 for both NCCO and SCCO in spite of the difference in the magnetic order. This result sheds a light on the disappearance of superconductivity on the over-doped side.

Computer simulation of Playback spectrum bumps due to pseudo gaps of MIG head (MIG 헤드 가상 갭에 의한 재생 전압 스펙트럼 Bump의 컴퓨터 시뮬레이션)

  • 한은실;조순철
    • Journal of the Korean Magnetics Society
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    • v.4 no.2
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    • pp.130-134
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    • 1994
  • This paper describes the occurance of bumps in playback spectrum while reading with MIG heads. The amplitudes of the bumps in theoretically predicted frequencies are investigated by computer simulation. Three cases of MIG head structure are simulated, one without pseudo gaps, the other two with pseudo gap thicknesses of $0.02\;\mu\textrm{m}\;and\;0.2\;\mu\textrm{m}$ on both sides of the main gap, respectively. It is assumed that metal powder tapes are used. The results show that the bumps occur at predicted frequencies and the amplitudes of the bumps agree well with predicted values.

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Pseudo-electromagnetism in graphene

  • Son, Young-Woo
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.11-11
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    • 2011
  • In this talk, I will discuss roles of pseudo vector and scalar potential in changing physical properties of graphene systems. First, graphene under small uniaxial strain is shown to be described by the generalized Weyl's Hamiltonian with inclusion of pseudo vector and scalar potential simultaneously [1]. Thus, strained graphene is predicted to exhibit velocity anisotropy as well as work function enhancement without any gap. Second, if homogeneous strains with different strengths are applied to each layer of bilayer graphene, transverse electric fields across the two layers can be generated without any external electronic sources, thereby opening an energy gap [2]. This phenomenon is made possible by generation of inequivalent pseudo scalar potentials in the two graphene layers. Third, when very tiny lateral interlayer shift occurs in bilayer graphene, the Fermi surfaces of the system are shown to undergo Lifshitz transition [3]. We will show that this unexpected hypersensitive electronic topological transition is caused by a unique interplay between the effective non-Abelian vector potential generated by sliding motions and Berry's phases associated with massless Dirac electrons.

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Characterizations of Interface-state Density between Top Silicon and Buried Oxide on Nano-SOI Substrate by using Pseudo-MOSFETs

  • Cho, Won-Ju
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.5 no.2
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    • pp.83-88
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    • 2005
  • The interface-states between the top silicon layer and buried oxide layer of nano-SOI substrate were developed. Also, the effects of thermal treatment processes on the interface-state distributions were investigated for the first time by using pseudo-MOSFETs. We found that the interface-state distributions were strongly influenced by the thermal treatment processes. The interface-states were generated by the rapid thermal annealing (RTA) process. Increasing the RTA temperature over $800^{\circ}C$, the interface-state density considerably increased. Especially, a peak of interface-states distribution that contributes a hump phenomenon of subthreshold curve in the inversion mode operation of pseudo-MOSFETs was observed at the conduction band side of the energy gap, hut it was not observed in the accumulation mode operation. On the other hand, the increased interface-state density by the RTA process was effectively reduced by the relatively low temperature annealing process in a conventional thermal annealing (CTA) process.

Class Specific Autoencoders Enhance Sample Diversity

  • Kumar, Teerath;Park, Jinbae;Ali, Muhammad Salman;Uddin, AFM Shahab;Bae, Sung-Ho
    • Journal of Broadcast Engineering
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    • v.26 no.7
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    • pp.844-854
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    • 2021
  • Semi-supervised learning (SSL) and few-shot learning (FSL) have shown impressive performance even then the volume of labeled data is very limited. However, SSL and FSL can encounter a significant performance degradation if the diversity gap between the labeled and unlabeled data is high. To reduce this diversity gap, we propose a novel scheme that relies on an autoencoder for generating pseudo examples. Specifically, the autoencoder is trained on a specific class using the available labeled data and the decoder of the trained autoencoder is then used to generate N samples of that specific class based on N random noise, sampled from a standard normal distribution. The above process is repeated for all the classes. Consequently, the generated data reduces the diversity gap and enhances the model performance. Extensive experiments on MNIST and FashionMNIST datasets for SSL and FSL verify the effectiveness of the proposed approach in terms of classification accuracy and robustness against adversarial attacks.

A Study on the Characteristics of Novel Pseudo-TN IPS Mode LC Cell (새로운 Pseudo-TN IPS 모드 액정 셀에 대한 특성 해석 연구)

  • 윤형진;윤석인;윤상호;원태영
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.41 no.8
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    • pp.59-65
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    • 2004
  • In this paper, we propose Pseudo-TN IPS mde(Pseudo-Twisted Nematic In-Plane Switching mode) based on IT(In-plane switching Twisted nematic) mode that increase contrast ratio from improving optical characteristics and analyze the characteristics of Pseudo-TN IPS uude. Optical transmittance is 25% higher for the PTN-IPS mode than for the IT mode. Because aperture ratio of the PIN-IPS is increased. And the control of Liquid Crystal for adjusting optical transmittance is more easier than IT mode, because optical transmittance variation is linear with applying voltage. Contrast ratio is 8% lower for the PTN-IPS mode than for the IT mode in the horizontal direction. But, Contrast ratio is 20% higher for the PTN-IPS mode than for the IT mode in the vertical direction. It has also cell gap margin and many benefits of IT mode, this may be used very well in the future LC Cell design.

Legal and Ethical Insight about Witch Hunt Issues on Online News and 'Pseudo Press' (온라인 매체상의 현대식 마녀사냥 이슈와 '유사언론 행위'간 법적·윤리적 논쟁에 대한 고찰)

  • Jeung, Woon Gap
    • The Journal of the Korea Contents Association
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    • v.18 no.7
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    • pp.1-9
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    • 2018
  • Present study investigated the crash phenomenon between freedom of press and pseudo press. For that researcher gathered online witch hunt cases from 2012 to 2017 and interpret with the logical basis of argument which needs to control pseudo press activity. On the other hand, present research arranged former studies about freedom of press and right of reputation and privacy as a counterpart that can be ethical debate. Futhermore, court case about right of small independent media where has less than 5 people also gathered. By Comparison of each ethical and legal basis, this study provide the insight which can inspire to think about real right of citizen and press.