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48 results on '"Kim, Jeong-Mok"'

1. Identifying intrinsic and extrinsic mechanisms of anisotropic magnetoresistance with terahertz probes

Author

Park, Ji-Ho, Ko, Hye-Won, Kim, Jeong-Mok, Park, Jungmin, Park, Seung-Young, Jo, Younghun, Park, Byong-Guk, Kim, Se Kwon, Lee, Kyung-Jin, and Kim, Kab-Jin

Subjects
Condensed Matter - Materials Science
Abstract

Identifying the intrinsic and extrinsic origins of magneto-transport in spin-orbit coupled systems has long been a central theme in condensed matter physics. However, it has been elusive owing to the lack of an appropriate experimental tool. In this work, using terahertz time-domain spectroscopy, we unambiguously disentangle the intrinsic and extrinsic contributions to the anisotropic magnetoresistance (AMR) of a permalloy film. We find that the scattering-independent intrinsic contribution to AMR is sizable and is as large as the scattering-dependent extrinsic contribution to AMR. Moreover, the portion of intrinsic contribution to total AMR increases with increasing temperature due to the reduction of extrinsic contribution. Further investigation reveals that the reduction of extrinsic contribution is caused by the phonon/magnon-induced negative AMR. Our result will stimulate further researches on other spin-orbit-interaction-induced phenomena for which identifying the intrinsic and extrinsic contributions is important.

Published
2021

10. Enhanced spin Seebeck effect via oxygen manipulation

Author

Kim, Jeong-Mok, Kim, Seok-Jong, Kang, Min-Gu, Choi, Jong-Guk, Lee, Soogil, Park, Jaehyeon, Van Phuoc, Cao, Kim, Kyoung-Whan, Kim, Kab-Jin, Jeong, Jong-Ryul, Lee, Kyung-Jin, and Park, Byong-Guk

Abstract

Spin Seebeck effect (SSE) refers to the generation of an electric voltage transverse to a temperature gradient via a magnon current. SSE offers the potential for efficient thermoelectric devices because the transverse geometry of SSE enables to utilize waste heat from a large-area source by greatly simplifying the device structure. However, SSE suffers from a low thermoelectric conversion efficiency that must be improved for widespread application. Here we show that the SSE substantially enhances by oxidizing a ferromagnet in normal metal/ferromagnet/oxide structures. In W/CoFeB/AlOx structures, voltage-induced interfacial oxidation of CoFeB modifies the SSE, resulting in the enhancement of thermoelectric signal by an order of magnitude. We describe a mechanism for the enhancement that results from a reduced exchange interaction of the oxidized region of ferromagnet, which in turn increases a temperature difference between magnons in the ferromagnet and electrons in the normal metal and/or a gradient of magnon chemical potential in the ferromagnet. Our result will invigorate research for thermoelectric conversion by suggesting a promising way of improving the SSE efficiency., Nature Communications, 14, ISSN:2041-1723

Published
2023

13. Spintronic Physical Unclonable Functions Based on Field‐Free Spin–Orbit‐Torque Switching

Author

Lee, Soogil, primary, Kang, Jaimin, additional, Kim, Jeong‐Mok, additional, Kim, Namhee, additional, Han, Donghyeon, additional, Lee, Taekhyeon, additional, Ko, San, additional, Yang, Jiseok, additional, Lee, Sanghwa, additional, Lee, Sungjun, additional, Koh, Daekyu, additional, Kang, Min‐Gu, additional, Lee, Jisung, additional, Noh, Sujung, additional, Lee, Hansaem, additional, Kwon, JoonHyun, additional, Baek, Seung‐heon Chris, additional, Kim, Kab‐Jin, additional, and Park, Byong‐Guk, additional

Published
2022
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46. The C-terminal domain of the transcriptional regulator BldD from Streptomyces coelicolor A3(2) constitutes a novel fold of winged-helix domains.

Author

Kim, Jeong‐Mok, Won, Hyung‐Sik, and Kang, Sa‐Ouk

Abstract

ABSTRACT BldD regulates transcription of key developmental genes in Streptomyces coelicolor. While the N-terminal domain is responsible for both dimerization and DNA binding, the structural and functional roles of the C-terminal domain (CTD) remain largely unexplored. Here, the solution structure of the BldD-CTD shows a novel winged-helix domain fold not compatible with DNA binding, due to the negatively charged surface and presence of an additional helix. Meanwhile, a small elongated groove with conserved hydrophobic patches surrounded by charged residues suggests that the BldD-CTD could be involved in protein-protein interactions that provide transcriptional regulation. Proteins 2014; 82:1093-1098. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Published
2014
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47. Identification of a non-pathogenic surrogate organism for chlorine dioxide (ClO2) gas treatment

Author

Kim, Jeong-Mok and Linton, Richard H.

Subjects
*FOODBORNE diseases, *BOVINE spongiform encephalopathy, *ANISAKIASIS, *MICROORGANISMS
Abstract

Abstract: The identification of non-pathogenic surrogate microorganisms is beneficial for determining and validating the efficacy of antimicrobial treatments in food manufacturing environments. A surrogate organism was identified to aid in the decontamination process of fresh produce when treated with chlorine dioxide (ClO2) gas. Thirty-two known strains of pathogenic and non-pathogenic microorganisms and seven unknown microbial isolates from mushroom, tomatoes, and strawberries were evaluated. The primary goal was to find alternative non-pathogenic organisms that had an equal or higher resistance compared to Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes. Among the strains tested, MR1 (mushroom isolate), E. coli O157:H7 C7927, E. coli O157:H7 204P, STB2 (strawberry isolate), and vegetative cells of Bacillus cereus 232 in wet inoculum were found to be the most resistant to gaseous ClO2 treatment at 0.3mg/l for 1min and D-values at 0.3mg/l ClO2 were 3.53, 1.95, 1.72, 1.68, and 1.57min, respectively. For identification, the MR1 and STB2 strains were identified using a Ribotyper™ with the EcoRI restriction enzyme of 16S rDNA sequence. MR1 was identified as Hafnia alvei with a similarity value of 94% using the ribotype pattern and with a 93.6% similarity using an API 20E strip, and with a 99% similarity using 16S rDNA analysis. The Ped-2E9-based cytotoxicity assay was conducted for the MRI strain extracellular toxin and whole cell toxicity and did not show cytotoxicity. Analysis, using multiplex PCR, was performed to verify absence of the eaeA gene. H. alvei is a suitable non-pathogenic surrogate, with higher resistance to ClO2 gas compared to pathogens studied, that may be useful to establish optimum conditions of ClO2 gas decontamination systems. [Copyright &y& Elsevier]

Published
2008
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48. Enhanced spin Seebeck effect via oxygen manipulation.

Author

Kim JM, Kim SJ, Kang MG, Choi JG, Lee S, Park J, Van Phuoc C, Kim KW, Kim KJ, Jeong JR, Lee KJ, and Park BG

Abstract

Spin Seebeck effect (SSE) refers to the generation of an electric voltage transverse to a temperature gradient via a magnon current. SSE offers the potential for efficient thermoelectric devices because the transverse geometry of SSE enables to utilize waste heat from a large-area source by greatly simplifying the device structure. However, SSE suffers from a low thermoelectric conversion efficiency that must be improved for widespread application. Here we show that the SSE substantially enhances by oxidizing a ferromagnet in normal metal/ferromagnet/oxide structures. In W/CoFeB/AlO x structures, voltage-induced interfacial oxidation of CoFeB modifies the SSE, resulting in the enhancement of thermoelectric signal by an order of magnitude. We describe a mechanism for the enhancement that results from a reduced exchange interaction of the oxidized region of ferromagnet, which in turn increases a temperature difference between magnons in the ferromagnet and electrons in the normal metal and/or a gradient of magnon chemical potential in the ferromagnet. Our result will invigorate research for thermoelectric conversion by suggesting a promising way of improving the SSE efficiency., (© 2023. The Author(s).)

Published
2023
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