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42 results on '"Namgung, Seon"'

1. Optoelectronic manifestation of orbital angular momentum driven by chiral hopping in helical Se chains

Author

Kim, Bumseop, Shin, Dongbin, Namgung, Seon, Park, Noejung, Kim, Kyoung-Whan, and Kim, Jeongwoo

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Chiral materials have garnered significant attention in the field of condensed matter physics. Nevertheless, the magnetic moment induced by the chiral spatial motion of electrons in helical materials, such as elemental Te and Se, remains inadequately understood. In this work, we investigate the development of quantum angular momentum enforced by chirality using static and time-dependent density functional theory calculations for an elemental Se chain. Our findings reveal the emergence of an unconventional orbital texture driven by the chiral geometry, giving rise to a non-vanishing current-induced orbital moment. By incorporating spin-orbit coupling, we demonstrate that a current-induced spin accumulation arises in the chiral chain, which fundamentally differs from the conventional Edelstein effect. Furthermore, we demonstrate the optoelectronic detection of the orbital angular momentum in the chiral Se chain, providing a conceptually novel alternative to the interband Berry curvature, which is ill-defined in low dimensions., Comment: 24 pages, 4 figures

Published
2023
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3. Defining the zerogap: cracking along the photolithographically defined Au–Cu–Au lines with sub-nanometer precision

Author

Kim Sunghwan, Das Bamadev, Ji Kang Hyeon, Moghaddam Mahsa Haddadi, Chen Cheng, Cha Jongjin, Namgung Seon, Lee Dukhyung, and Kim Dai-Sik

Subjects
metal crack, photolithography, quantum conductance, sub-nanometer, zerogap fabrication, Physics, QC1-999
Abstract

Cracks are formed along the photolithographically pre-determined lines with extremely high yield and repeatability, when Cu clusters are introduced between planarized Au thin films sequentially deposited on a PET substrate. These clusters act as nanometer-sized spacers preventing the formation of contiguous metallic bond between the adjacent Au layers which will render prepatterned-cracking impossible. While the effective gap width is initially zero in the optical sense from microwaves all the way to the visible, outer-bending the PET substrate allows the gap width tuning into the 100 nm range, with the stability and controllability in the ranges of 100 s and Angstrom-scale, respectively. It is anticipated that our wafer-scale prepatterned crack technology with an unprecedented mixture of macroscopic length and Angstrom-scale controllability will open-up many applications in optoelectronics, quantum photonics and photocatalysis.

Published
2023
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7. Surface-Programmed Assembly for Nanomanufacturing

Author

Hong, Seunghun, primary, Park, Sung Young, additional, Kang, Juwan, additional, Kim, Tae–Kyeong, additional, Koh, Juntae, additional, Heo, Kwang, additional, Byun, Kyung-Eun, additional, Lee, Dong Joon, additional, and Namgung, Seon, additional

Published
2017
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10. Nanoscale Etching of La0.7Sr0.3MnO3 Without Etch Lag Using Chlorine Based Inductively Coupled Plasma.

Author

Sarkar, Nimphy, Han, Jaewoo, Dalayoan, Daryll Joseph Chavez, Behera, Satyabrat, Lee, Sang-Hyuk, Chen, Cheng, Kim, Dai-Sik, Sohn, Changhee, and Namgung, Seon

Abstract

La0.7Sr0.3MnO3 (LSMO) has been considered as a promising material for future electronic and spintronic device application due to its unique properties such as pure spin polarization, colossal magnetoresistance, and high temperature coefficient of resistance (TCR). To apply this promising material for practical application, large epitaxial LSMO layers should be etched into micro- and nano-scale device structures. However, a comprehensive study on the etch of LSMO has not been demonstrated yet. Herein, the etch rates of LSMO are studied using inductively coupled plasma reactive ion etching (ICP-RIE) method, while controlling critical etching parameters such as ICP source power, radio frequency (rf) chuck power, etching gas ratio, and chamber pressure. We found that the etching process can be applied to nanoscale structures (down to 100 nm) without etch lag effect, exhibiting smaller etch depth in smaller features. This study will provide a good reference for the etching and the engineering of LSMO toward future electronic and spintronic devices such as highly sensitive bolometers and low-power memory devices. [ABSTRACT FROM AUTHOR]

Published
2023
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13. Nanoscale Etching of La0.7Sr0.3MnO3Without Etch Lag Using Chlorine Based Inductively Coupled Plasma

Author

Sarkar, Nimphy, Han, Jaewoo, Dalayoan, Daryll Joseph Chavez, Behera, Satyabrat, Lee, Sang-Hyuk, Chen, Cheng, Kim, Dai-Sik, Sohn, Changhee, and Namgung, Seon

Abstract

La0.7Sr0.3MnO3(LSMO) has been considered as a promising material for future electronic and spintronic device application due to its unique properties such as pure spin polarization, colossal magnetoresistance, and high temperature coefficient of resistance (TCR). To apply this promising material for practical application, large epitaxial LSMO layers should be etched into micro- and nano-scale device structures. However, a comprehensive study on the etch of LSMO has not been demonstrated yet. Herein, the etch rates of LSMO are studied using inductively coupled plasma reactive ion etching (ICP-RIE) method, while controlling critical etching parameters such as ICP source power, radio frequency (rf) chuck power, etching gas ratio, and chamber pressure. We found that the etching process can be applied to nanoscale structures (down to 100 nm) without etch lag effect, exhibiting smaller etch depth in smaller features. This study will provide a good reference for the etching and the engineering of LSMO toward future electronic and spintronic devices such as highly sensitive bolometers and low-power memory devices.

Published
2023
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17. Surface-Programmed Assembly for Nanomanufacturing

Author

Heo, Kwang, primary, Byun, Kyung-Eun, additional, Kang, Juwan, additional, Young Park, Sung, additional, Joon Lee, Dong, additional, Hong, Seunghun, additional, Kim, Tae–Kyeong, additional, Koh, Juntae, additional, and Namgung, Seon, additional

Published
2006
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23. Multimodal Photodiode and Phototransistor Device Based on Two-Dimensional Materials

Author

Namgung, Seon, Shaver, Jonah, Oh, Sang-Hyun, and Koester, Steven J.

Abstract

With strong light–matter interaction in their atomically thin layered structures, two-dimensional (2D) materials have been widely investigated for optoelectronic applications such as photodetectors and photovoltaic devices. Depending on the aim of optoelectronic applications, different device structures have been employed. Lateral phototransistor structures have been employed for high optical gain, while vertical photodiode structures have been employed for fast response and low power operation. Herein, we demonstrate a multimodal photodetector platform based on 2D materials, combining both a phototransistor and a photodiode and taking the corresponding desirable characteristics from each structure within a single device. In this platform, a multilayered transition-metal dichalcogenide flake is transferred on top of metal electrodes, and a transparent gate electrode is employed. The channel region of the flake between electrodes operates as a phototransistor providing a high gain mode, while the electrode region in the same flake operates as a vertical Schottky photodiode providing a fast response mode. These modes can be dynamically selected by controlling the drain voltage and gate voltage.

Published
2024
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