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1. HyperCLOVA X Technical Report

Author

Yoo, Kang Min, Han, Jaegeun, In, Sookyo, Jeon, Heewon, Jeong, Jisu, Kang, Jaewook, Kim, Hyunwook, Kim, Kyung-Min, Kim, Munhyong, Kim, Sungju, Kwak, Donghyun, Kwak, Hanock, Kwon, Se Jung, Lee, Bado, Lee, Dongsoo, Lee, Gichang, Lee, Jooho, Park, Baeseong, Shin, Seongjin, Yu, Joonsang, Baek, Seolki, Byeon, Sumin, Cho, Eungsup, Choe, Dooseok, Han, Jeesung, Jin, Youngkyun, Jun, Hyein, Jung, Jaeseung, Kim, Chanwoong, Kim, Jinhong, Kim, Jinuk, Lee, Dokyeong, Park, Dongwook, Sohn, Jeong Min, Han, Sujung, Heo, Jiae, Hong, Sungju, Jeon, Mina, Jung, Hyunhoon, Jung, Jungeun, Jung, Wangkyo, Kim, Chungjoon, Kim, Hyeri, Kim, Jonghyun, Kim, Min Young, Lee, Soeun, Park, Joonhee, Shin, Jieun, Yang, Sojin, Yoon, Jungsoon, Lee, Hwaran, Bae, Sanghwan, Cha, Jeehwan, Gylleus, Karl, Ham, Donghoon, Hong, Mihak, Hong, Youngki, Hong, Yunki, Jang, Dahyun, Jeon, Hyojun, Jeon, Yujin, Jeong, Yeji, Ji, Myunggeun, Jin, Yeguk, Jo, Chansong, Joo, Shinyoung, Jung, Seunghwan, Kim, Adrian Jungmyung, Kim, Byoung Hoon, Kim, Hyomin, Kim, Jungwhan, Kim, Minkyoung, Kim, Minseung, Kim, Sungdong, Kim, Yonghee, Kim, Youngjun, Kim, Youngkwan, Ko, Donghyeon, Lee, Dughyun, Lee, Ha Young, Lee, Jaehong, Lee, Jieun, Lee, Jonghyun, Lee, Jongjin, Lee, Min Young, Lee, Yehbin, Min, Taehong, Min, Yuri, Moon, Kiyoon, Oh, Hyangnam, Park, Jaesun, Park, Kyuyon, Park, Younghun, Seo, Hanbae, Seo, Seunghyun, Sim, Mihyun, Son, Gyubin, Yeo, Matt, Yeom, Kyung Hoon, Yoo, Wonjoon, You, Myungin, Ahn, Doheon, Ahn, Homin, Ahn, Joohee, Ahn, Seongmin, An, Chanwoo, An, Hyeryun, An, Junho, An, Sang-Min, Byun, Boram, Byun, Eunbin, Cha, Jongho, Chang, Minji, Chang, Seunggyu, Cho, Haesong, Cho, Youngdo, Choi, Dalnim, Choi, Daseul, Choi, Hyoseok, Choi, Minseong, Choi, Sangho, Choi, Seongjae, Choi, Wooyong, Chun, Sewhan, Go, Dong Young, Ham, Chiheon, Han, Danbi, Han, Jaemin, Hong, Moonyoung, Hong, Sung Bum, Hwang, Dong-Hyun, Hwang, Seongchan, Im, Jinbae, Jang, Hyuk Jin, Jang, Jaehyung, Jang, Jaeni, Jang, Sihyeon, Jang, Sungwon, Jeon, Joonha, Jeong, Daun, Jeong, Joonhyun, Jeong, Kyeongseok, Jeong, Mini, Jin, Sol, Jo, Hanbyeol, Jo, Hanju, Jo, Minjung, Jung, Chaeyoon, Jung, Hyungsik, Jung, Jaeuk, Jung, Ju Hwan, Jung, Kwangsun, Jung, Seungjae, Ka, Soonwon, Kang, Donghan, Kang, Soyoung, Kil, Taeho, Kim, Areum, Kim, Beomyoung, Kim, Byeongwook, Kim, Daehee, Kim, Dong-Gyun, Kim, Donggook, Kim, Donghyun, Kim, Euna, Kim, Eunchul, Kim, Geewook, Kim, Gyu Ri, Kim, Hanbyul, Kim, Heesu, Kim, Isaac, Kim, Jeonghoon, Kim, Jihye, Kim, Joonghoon, Kim, Minjae, Kim, Minsub, Kim, Pil Hwan, Kim, Sammy, Kim, Seokhun, Kim, Seonghyeon, Kim, Soojin, Kim, Soong, Kim, Soyoon, Kim, Sunyoung, Kim, Taeho, Kim, Wonho, Kim, Yoonsik, Kim, You Jin, Kim, Yuri, Kwon, Beomseok, Kwon, Ohsung, Kwon, Yoo-Hwan, Lee, Anna, Lee, Byungwook, Lee, Changho, Lee, Daun, Lee, Dongjae, Lee, Ha-Ram, Lee, Hodong, Lee, Hwiyeong, Lee, Hyunmi, Lee, Injae, Lee, Jaeung, Lee, Jeongsang, Lee, Jisoo, Lee, Jongsoo, Lee, Joongjae, Lee, Juhan, Lee, Jung Hyun, Lee, Junghoon, Lee, Junwoo, Lee, Se Yun, Lee, Sujin, Lee, Sungjae, Lee, Sungwoo, Lee, Wonjae, Lee, Zoo Hyun, Lim, Jong Kun, Lim, Kun, Lim, Taemin, Na, Nuri, Nam, Jeongyeon, Nam, Kyeong-Min, Noh, Yeonseog, Oh, Biro, Oh, Jung-Sik, Oh, Solgil, Oh, Yeontaek, Park, Boyoun, Park, Cheonbok, Park, Dongju, Park, Hyeonjin, Park, Hyun Tae, Park, Hyunjung, Park, Jihye, Park, Jooseok, Park, Junghwan, Park, Jungsoo, Park, Miru, Park, Sang Hee, Park, Seunghyun, Park, Soyoung, Park, Taerim, Park, Wonkyeong, Ryu, Hyunjoon, Ryu, Jeonghun, Ryu, Nahyeon, Seo, Soonshin, Seo, Suk Min, Shim, Yoonjeong, Shin, Kyuyong, Shin, Wonkwang, Sim, Hyun, Sim, Woongseob, Soh, Hyejin, Son, Bokyong, Son, Hyunjun, Son, Seulah, Song, Chi-Yun, Song, Chiyoung, Song, Ka Yeon, Song, Minchul, Song, Seungmin, Wang, Jisung, Yeo, Yonggoo, Yi, Myeong Yeon, Yim, Moon Bin, Yoo, Taehwan, Yoo, Youngjoon, Yoon, Sungmin, Yoon, Young Jin, Yu, Hangyeol, Yu, Ui Seon, Zuo, Xingdong, Bae, Jeongin, Bae, Joungeun, Cho, Hyunsoo, Cho, Seonghyun, Cho, Yongjin, Choi, Taekyoon, Choi, Yera, Chung, Jiwan, Han, Zhenghui, Heo, Byeongho, Hong, Euisuk, Hwang, Taebaek, Im, Seonyeol, Jegal, Sumin, Jeon, Sumin, Jeong, Yelim, Jeong, Yonghyun, Jiang, Can, Jiang, Juyong, Jin, Jiho, Jo, Ara, Jo, Younghyun, Jung, Hoyoun, Jung, Juyoung, Kang, Seunghyeong, Kim, Dae Hee, Kim, Ginam, Kim, Hangyeol, Kim, Heeseung, Kim, Hyojin, Kim, Hyojun, Kim, Hyun-Ah, Kim, Jeehye, Kim, Jin-Hwa, Kim, Jiseon, Kim, Jonghak, Kim, Jung Yoon, Kim, Rak Yeong, Kim, Seongjin, Kim, Seoyoon, Kim, Sewon, Kim, Sooyoung, Kim, Sukyoung, Kim, Taeyong, Ko, Naeun, Koo, Bonseung, Kwak, Heeyoung, Kwon, Haena, Kwon, Youngjin, Lee, Boram, Lee, Bruce W., Lee, Dagyeong, Lee, Erin, Lee, Euijin, Lee, Ha Gyeong, Lee, Hyojin, Lee, Hyunjeong, Lee, Jeeyoon, Lee, Jeonghyun, Lee, Jongheok, Lee, Joonhyung, Lee, Junhyuk, Lee, Mingu, Lee, Nayeon, Lee, Sangkyu, Lee, Se Young, Lee, Seulgi, Lee, Seung Jin, Lee, Suhyeon, Lee, Yeonjae, Lee, Yesol, Lee, Youngbeom, Lee, Yujin, Li, Shaodong, Liu, Tianyu, Moon, Seong-Eun, Moon, Taehong, Nihlenramstroem, Max-Lasse, Oh, Wonseok, Oh, Yuri, Park, Hongbeen, Park, Hyekyung, Park, Jaeho, Park, Nohil, Park, Sangjin, Ryu, Jiwon, Ryu, Miru, Ryu, Simo, Seo, Ahreum, Seo, Hee, Seo, Kangdeok, Shin, Jamin, Shin, Seungyoun, Sin, Heetae, Wang, Jiangping, Wang, Lei, Xiang, Ning, Xiao, Longxiang, Xu, Jing, Yi, Seonyeong, Yoo, Haanju, Yoo, Haneul, Yoo, Hwanhee, Yu, Liang, Yu, Youngjae, Yuan, Weijie, Zeng, Bo, Zhou, Qian, Cho, Kyunghyun, Ha, Jung-Woo, Park, Joonsuk, Hwang, Jihyun, Kwon, Hyoung Jo, Kwon, Soonyong, Lee, Jungyeon, Lee, Seungho, Lim, Seonghyeon, Noh, Hyunkyung, Choi, Seungho, Lee, Sang-Woo, Lim, Jung Hwa, Sung, Nako, Yoo, Kang Min, Han, Jaegeun, In, Sookyo, Jeon, Heewon, Jeong, Jisu, Kang, Jaewook, Kim, Hyunwook, Kim, Kyung-Min, Kim, Munhyong, Kim, Sungju, Kwak, Donghyun, Kwak, Hanock, Kwon, Se Jung, Lee, Bado, Lee, Dongsoo, Lee, Gichang, Lee, Jooho, Park, Baeseong, Shin, Seongjin, Yu, Joonsang, Baek, Seolki, Byeon, Sumin, Cho, Eungsup, Choe, Dooseok, Han, Jeesung, Jin, Youngkyun, Jun, Hyein, Jung, Jaeseung, Kim, Chanwoong, Kim, Jinhong, Kim, Jinuk, Lee, Dokyeong, Park, Dongwook, Sohn, Jeong Min, Han, Sujung, Heo, Jiae, Hong, Sungju, Jeon, Mina, Jung, Hyunhoon, Jung, Jungeun, Jung, Wangkyo, Kim, Chungjoon, Kim, Hyeri, Kim, Jonghyun, Kim, Min Young, Lee, Soeun, Park, Joonhee, Shin, Jieun, Yang, Sojin, Yoon, Jungsoon, Lee, Hwaran, Bae, Sanghwan, Cha, Jeehwan, Gylleus, Karl, Ham, Donghoon, Hong, Mihak, Hong, Youngki, Hong, Yunki, Jang, Dahyun, Jeon, Hyojun, Jeon, Yujin, Jeong, Yeji, Ji, Myunggeun, Jin, Yeguk, Jo, Chansong, Joo, Shinyoung, Jung, Seunghwan, Kim, Adrian Jungmyung, Kim, Byoung Hoon, Kim, Hyomin, Kim, Jungwhan, Kim, Minkyoung, Kim, Minseung, Kim, Sungdong, Kim, Yonghee, Kim, Youngjun, Kim, Youngkwan, Ko, Donghyeon, Lee, Dughyun, Lee, Ha Young, Lee, Jaehong, Lee, Jieun, Lee, Jonghyun, Lee, Jongjin, Lee, Min Young, Lee, Yehbin, Min, Taehong, Min, Yuri, Moon, Kiyoon, Oh, Hyangnam, Park, Jaesun, Park, Kyuyon, Park, Younghun, Seo, Hanbae, Seo, Seunghyun, Sim, Mihyun, Son, Gyubin, Yeo, Matt, Yeom, Kyung Hoon, Yoo, Wonjoon, You, Myungin, Ahn, Doheon, Ahn, Homin, Ahn, Joohee, Ahn, Seongmin, An, Chanwoo, An, Hyeryun, An, Junho, An, Sang-Min, Byun, Boram, Byun, Eunbin, Cha, Jongho, Chang, Minji, Chang, Seunggyu, Cho, Haesong, Cho, Youngdo, Choi, Dalnim, Choi, Daseul, Choi, Hyoseok, Choi, Minseong, Choi, Sangho, Choi, Seongjae, Choi, Wooyong, Chun, Sewhan, Go, Dong Young, Ham, Chiheon, Han, Danbi, Han, Jaemin, Hong, Moonyoung, Hong, Sung Bum, Hwang, Dong-Hyun, Hwang, Seongchan, Im, Jinbae, Jang, Hyuk Jin, Jang, Jaehyung, Jang, Jaeni, Jang, Sihyeon, Jang, Sungwon, Jeon, Joonha, Jeong, Daun, Jeong, Joonhyun, Jeong, Kyeongseok, Jeong, Mini, Jin, Sol, Jo, Hanbyeol, Jo, Hanju, Jo, Minjung, Jung, Chaeyoon, Jung, Hyungsik, Jung, Jaeuk, Jung, Ju Hwan, Jung, Kwangsun, Jung, Seungjae, Ka, Soonwon, Kang, Donghan, Kang, Soyoung, Kil, Taeho, Kim, Areum, Kim, Beomyoung, Kim, Byeongwook, Kim, Daehee, Kim, Dong-Gyun, Kim, Donggook, Kim, Donghyun, Kim, Euna, Kim, Eunchul, Kim, Geewook, Kim, Gyu Ri, Kim, Hanbyul, Kim, Heesu, Kim, Isaac, Kim, Jeonghoon, Kim, Jihye, Kim, Joonghoon, Kim, Minjae, Kim, Minsub, Kim, Pil Hwan, Kim, Sammy, Kim, Seokhun, Kim, Seonghyeon, Kim, Soojin, Kim, Soong, Kim, Soyoon, Kim, Sunyoung, Kim, Taeho, Kim, Wonho, Kim, Yoonsik, Kim, You Jin, Kim, Yuri, Kwon, Beomseok, Kwon, Ohsung, Kwon, Yoo-Hwan, Lee, Anna, Lee, Byungwook, Lee, Changho, Lee, Daun, Lee, Dongjae, Lee, Ha-Ram, Lee, Hodong, Lee, Hwiyeong, Lee, Hyunmi, Lee, Injae, Lee, Jaeung, Lee, Jeongsang, Lee, Jisoo, Lee, Jongsoo, Lee, Joongjae, Lee, Juhan, Lee, Jung Hyun, Lee, Junghoon, Lee, Junwoo, Lee, Se Yun, Lee, Sujin, Lee, Sungjae, Lee, Sungwoo, Lee, Wonjae, Lee, Zoo Hyun, Lim, Jong Kun, Lim, Kun, Lim, Taemin, Na, Nuri, Nam, Jeongyeon, Nam, Kyeong-Min, Noh, Yeonseog, Oh, Biro, Oh, Jung-Sik, Oh, Solgil, Oh, Yeontaek, Park, Boyoun, Park, Cheonbok, Park, Dongju, Park, Hyeonjin, Park, Hyun Tae, Park, Hyunjung, Park, Jihye, Park, Jooseok, Park, Junghwan, Park, Jungsoo, Park, Miru, Park, Sang Hee, Park, Seunghyun, Park, Soyoung, Park, Taerim, Park, Wonkyeong, Ryu, Hyunjoon, Ryu, Jeonghun, Ryu, Nahyeon, Seo, Soonshin, Seo, Suk Min, Shim, Yoonjeong, Shin, Kyuyong, Shin, Wonkwang, Sim, Hyun, Sim, Woongseob, Soh, Hyejin, Son, Bokyong, Son, Hyunjun, Son, Seulah, Song, Chi-Yun, Song, Chiyoung, Song, Ka Yeon, Song, Minchul, Song, Seungmin, Wang, Jisung, Yeo, Yonggoo, Yi, Myeong Yeon, Yim, Moon Bin, Yoo, Taehwan, Yoo, Youngjoon, Yoon, Sungmin, Yoon, Young Jin, Yu, Hangyeol, Yu, Ui Seon, Zuo, Xingdong, Bae, Jeongin, Bae, Joungeun, Cho, Hyunsoo, Cho, Seonghyun, Cho, Yongjin, Choi, Taekyoon, Choi, Yera, Chung, Jiwan, Han, Zhenghui, Heo, Byeongho, Hong, Euisuk, Hwang, Taebaek, Im, Seonyeol, Jegal, Sumin, Jeon, Sumin, Jeong, Yelim, Jeong, Yonghyun, Jiang, Can, Jiang, Juyong, Jin, Jiho, Jo, Ara, Jo, Younghyun, Jung, Hoyoun, Jung, Juyoung, Kang, Seunghyeong, Kim, Dae Hee, Kim, Ginam, Kim, Hangyeol, Kim, Heeseung, Kim, Hyojin, Kim, Hyojun, Kim, Hyun-Ah, Kim, Jeehye, Kim, Jin-Hwa, Kim, Jiseon, Kim, Jonghak, Kim, Jung Yoon, Kim, Rak Yeong, Kim, Seongjin, Kim, Seoyoon, Kim, Sewon, Kim, Sooyoung, Kim, Sukyoung, Kim, Taeyong, Ko, Naeun, Koo, Bonseung, Kwak, Heeyoung, Kwon, Haena, Kwon, Youngjin, Lee, Boram, Lee, Bruce W., Lee, Dagyeong, Lee, Erin, Lee, Euijin, Lee, Ha Gyeong, Lee, Hyojin, Lee, Hyunjeong, Lee, Jeeyoon, Lee, Jeonghyun, Lee, Jongheok, Lee, Joonhyung, Lee, Junhyuk, Lee, Mingu, Lee, Nayeon, Lee, Sangkyu, Lee, Se Young, Lee, Seulgi, Lee, Seung Jin, Lee, Suhyeon, Lee, Yeonjae, Lee, Yesol, Lee, Youngbeom, Lee, Yujin, Li, Shaodong, Liu, Tianyu, Moon, Seong-Eun, Moon, Taehong, Nihlenramstroem, Max-Lasse, Oh, Wonseok, Oh, Yuri, Park, Hongbeen, Park, Hyekyung, Park, Jaeho, Park, Nohil, Park, Sangjin, Ryu, Jiwon, Ryu, Miru, Ryu, Simo, Seo, Ahreum, Seo, Hee, Seo, Kangdeok, Shin, Jamin, Shin, Seungyoun, Sin, Heetae, Wang, Jiangping, Wang, Lei, Xiang, Ning, Xiao, Longxiang, Xu, Jing, Yi, Seonyeong, Yoo, Haanju, Yoo, Haneul, Yoo, Hwanhee, Yu, Liang, Yu, Youngjae, Yuan, Weijie, Zeng, Bo, Zhou, Qian, Cho, Kyunghyun, Ha, Jung-Woo, Park, Joonsuk, Hwang, Jihyun, Kwon, Hyoung Jo, Kwon, Soonyong, Lee, Jungyeon, Lee, Seungho, Lim, Seonghyeon, Noh, Hyunkyung, Choi, Seungho, Lee, Sang-Woo, Lim, Jung Hwa, and Sung, Nako

Abstract

We introduce HyperCLOVA X, a family of large language models (LLMs) tailored to the Korean language and culture, along with competitive capabilities in English, math, and coding. HyperCLOVA X was trained on a balanced mix of Korean, English, and code data, followed by instruction-tuning with high-quality human-annotated datasets while abiding by strict safety guidelines reflecting our commitment to responsible AI. The model is evaluated across various benchmarks, including comprehensive reasoning, knowledge, commonsense, factuality, coding, math, chatting, instruction-following, and harmlessness, in both Korean and English. HyperCLOVA X exhibits strong reasoning capabilities in Korean backed by a deep understanding of the language and cultural nuances. Further analysis of the inherent bilingual nature and its extension to multilingualism highlights the model's cross-lingual proficiency and strong generalization ability to untargeted languages, including machine translation between several language pairs and cross-lingual inference tasks. We believe that HyperCLOVA X can provide helpful guidance for regions or countries in developing their sovereign LLMs., Comment: 44 pages; updated authors list and fixed author names

Published
2024

2. Application of Convolutional Neural Network in Pneumonia Chest Image Classification

Author

Park, JungHwan, Wu, Yingnian1, Park, JungHwan, Park, JungHwan, Wu, Yingnian1, and Park, JungHwan

Abstract

In this application, multiple Convolutional Neural Network models with different complexities arebuilt for finding the most moderate fitting. The bias-variance tradeoff and the ways of tuning the model parameters were introduced to guide the readers who have little knowledge in building neural network models for the image classification problem.

Published
2022

3. Application of Convolutional Neural Network in Pneumonia Chest Image Classification

Author

Park, JungHwan, Wu, Yingnian1, Park, JungHwan, Park, JungHwan, Wu, Yingnian1, and Park, JungHwan

Abstract

In this application, multiple Convolutional Neural Network models with different complexities arebuilt for finding the most moderate fitting. The bias-variance tradeoff and the ways of tuning the model parameters were introduced to guide the readers who have little knowledge in building neural network models for the image classification problem.

Published
2022

4. Effects of Mn-substitution on the valence bond solid in Li2RuO3

Author

Yun, Seokhwan, Lee, Ki Hoon, Kim, Chaebin, Park, Junghwan, Kim, Min-Gyu, Cho, Deok-Yong, Khomskii, D., I, Park, Je-Geun, Yun, Seokhwan, Lee, Ki Hoon, Kim, Chaebin, Park, Junghwan, Kim, Min-Gyu, Cho, Deok-Yong, Khomskii, D., I, and Park, Je-Geun

Abstract

Li2RuO3 with a honeycomb structure undergoes a drastic transition from a regular honeycomb lattice with the C2/m space group to a valence-bond solid state of the P2(1)/m space group with an extremely strong dimerization at 550 K. We synthesized Li2Ru1-xMnxO3 with a full solid solution and investigated doping effects on the valence-bond solid state as a function of Mn content. The valence-bond solid state is found to be stable up to x = 0.2, based on our extensive experiments: structural studies, resistivity, and magnetic susceptibility. On the other hand, the extended x-ray absorption fine-structure analyses show that the dimer local structure remains robust even above x = 0.2 with a minimal effect on the dimer bond length. This indicates that the locally disordered dimer structure survives well into the Mn-rich phase even though the thermodynamically stable average structure has the C2/m space group. Our results prove that the dimer formation in Li2RuO3 is predominantly a local phenomenon driven by the formation of orbitally assisted metal-metal bonds and that these dimers are relatively robust against doping-induced disorder.

Published
2021

5. Effects of Mn-substitution on the valence bond solid in Li2RuO3

Author

Yun, Seokhwan, Lee, Ki Hoon, Kim, Chaebin, Park, Junghwan, Kim, Min-Gyu, Cho, Deok-Yong, Khomskii, D., I, Park, Je-Geun, Yun, Seokhwan, Lee, Ki Hoon, Kim, Chaebin, Park, Junghwan, Kim, Min-Gyu, Cho, Deok-Yong, Khomskii, D., I, and Park, Je-Geun

Abstract

Li2RuO3 with a honeycomb structure undergoes a drastic transition from a regular honeycomb lattice with the C2/m space group to a valence-bond solid state of the P2(1)/m space group with an extremely strong dimerization at 550 K. We synthesized Li2Ru1-xMnxO3 with a full solid solution and investigated doping effects on the valence-bond solid state as a function of Mn content. The valence-bond solid state is found to be stable up to x = 0.2, based on our extensive experiments: structural studies, resistivity, and magnetic susceptibility. On the other hand, the extended x-ray absorption fine-structure analyses show that the dimer local structure remains robust even above x = 0.2 with a minimal effect on the dimer bond length. This indicates that the locally disordered dimer structure survives well into the Mn-rich phase even though the thermodynamically stable average structure has the C2/m space group. Our results prove that the dimer formation in Li2RuO3 is predominantly a local phenomenon driven by the formation of orbitally assisted metal-metal bonds and that these dimers are relatively robust against doping-induced disorder.

Published
2021

6. Magnetic and electrical anisotropy with correlation and orbital effects in dimerized honeycomb ruthenate Li2RuO3

Author

Yun, Seokhwan, Lee, Ki Hoon, Park, Se Young, Tan, Teck-Yee, Park, Junghwan, Kang, Soonmin, Khomskii, D., I, Jo, Younjung, Park, Je-Geun, Yun, Seokhwan, Lee, Ki Hoon, Park, Se Young, Tan, Teck-Yee, Park, Junghwan, Kang, Soonmin, Khomskii, D., I, Jo, Younjung, and Park, Je-Geun

Abstract

Li2RuO3 undergoes a structural transition at a relatively high temperature of 550 K with a distinct dimerization of Ru-Ru bonds on the otherwise isotropic honeycomb lattice. It exhibits a unique herringbone dimerization pattern with an unusually large value of bond shrinkage, about similar to 0.5 angstrom. However, many questions still remain about its origin and its effect on the physical properties. In this work, using high-quality single crystals we investigated the anisotropy of resistivity (rho) and magnetic susceptibility (chi) to find a very clear anisotropy: rho(c*) > rho(b) > rho(a) and chi(b) > chi(a) > chi(c*). We also carried out density functional calculations for possible theoretical interpretations, and concluded that this anisotropic behavior is due to the correlation effects combined with the unique orbital structure and the dimerization of Ru 4d bands.

Published
2019

7. Magnetic and electrical anisotropy with correlation and orbital effects in dimerized honeycomb ruthenate Li2RuO3

Author

Yun, Seokhwan, Lee, Ki Hoon, Park, Se Young, Tan, Teck-Yee, Park, Junghwan, Kang, Soonmin, Khomskii, D., I, Jo, Younjung, Park, Je-Geun, Yun, Seokhwan, Lee, Ki Hoon, Park, Se Young, Tan, Teck-Yee, Park, Junghwan, Kang, Soonmin, Khomskii, D., I, Jo, Younjung, and Park, Je-Geun

Abstract

Li2RuO3 undergoes a structural transition at a relatively high temperature of 550 K with a distinct dimerization of Ru-Ru bonds on the otherwise isotropic honeycomb lattice. It exhibits a unique herringbone dimerization pattern with an unusually large value of bond shrinkage, about similar to 0.5 angstrom. However, many questions still remain about its origin and its effect on the physical properties. In this work, using high-quality single crystals we investigated the anisotropy of resistivity (rho) and magnetic susceptibility (chi) to find a very clear anisotropy: rho(c*) > rho(b) > rho(a) and chi(b) > chi(a) > chi(c*). We also carried out density functional calculations for possible theoretical interpretations, and concluded that this anisotropic behavior is due to the correlation effects combined with the unique orbital structure and the dimerization of Ru 4d bands.

Published
2019

8. Robust singlet dimers with fragile ordering in two-dimensional honeycomb lattice of Li2RuO3

Author

Park, Junghwan, Tan, Teck-Yee, Adroja, D. T., Daoud-Aladine, A., Choi, Seongil, Cho, Deok-Yong, Lee, Sang-Hyun, Kim, Jiyeon, Sim, Hasung, Morioka, T., Nojiri, H., Krishnamurthy, V. V., Manuel, P., Lees, M. R., Streltsov, S. V., Khomskii, D. I., Park, Je-Geun, Park, Junghwan, Tan, Teck-Yee, Adroja, D. T., Daoud-Aladine, A., Choi, Seongil, Cho, Deok-Yong, Lee, Sang-Hyun, Kim, Jiyeon, Sim, Hasung, Morioka, T., Nojiri, H., Krishnamurthy, V. V., Manuel, P., Lees, M. R., Streltsov, S. V., Khomskii, D. I., and Park, Je-Geun

Abstract

When an electronic system has strong correlations and a large spin-orbit interaction, it often exhibits a plethora of mutually competing quantum phases. How a particular quantum ground state is selected out of several possibilities is a very interesting question. However, equally fascinating is how such a quantum entangled state breaks up due to perturbation. This important question has relevance in very diverse fields of science from strongly correlated electron physics to quantum information. Here we report that a quantum entangled dimerized state or valence bond crystal (VBC) phase of Li2RuO3 shows nontrivial doping dependence as we perturb the Ru honeycomb lattice by replacing Ru with Li. Through extensive experimental studies, we demonstrate that the VBC phase melts into a valence bond liquid phase of the RVB (resonating valence bond) type. This system offers an interesting playground where one can test and refine our current understanding of the quantum competing phases in a single compound.

Published
2016

9. Robust singlet dimers with fragile ordering in two-dimensional honeycomb lattice of Li2RuO3

Author

Park, Junghwan, Tan, Teck-Yee, Adroja, D. T., Daoud-Aladine, A., Choi, Seongil, Cho, Deok-Yong, Lee, Sang-Hyun, Kim, Jiyeon, Sim, Hasung, Morioka, T., Nojiri, H., Krishnamurthy, V. V., Manuel, P., Lees, M. R., Streltsov, S. V., Khomskii, D. I., Park, Je-Geun, Park, Junghwan, Tan, Teck-Yee, Adroja, D. T., Daoud-Aladine, A., Choi, Seongil, Cho, Deok-Yong, Lee, Sang-Hyun, Kim, Jiyeon, Sim, Hasung, Morioka, T., Nojiri, H., Krishnamurthy, V. V., Manuel, P., Lees, M. R., Streltsov, S. V., Khomskii, D. I., and Park, Je-Geun

Published
2016

10. Robust singlet dimers with fragile ordering in two-dimensional honeycomb lattice of Li2RuO3

Author

Park, Junghwan, Tan, Teck-Yee, Adroja, D. T., Daoud-Aladine, A., Choi, Seongil, Cho, Deok-Yong, Lee, Sang-Hyun, Kim, Jiyeon, Sim, Hasung, Morioka, T., Nojiri, H., Krishnamurthy, V. V., Manuel, P., Lees, M. R., Streltsov, S. V., Khomskii, D. I., Park, Je-Geun, Park, Junghwan, Tan, Teck-Yee, Adroja, D. T., Daoud-Aladine, A., Choi, Seongil, Cho, Deok-Yong, Lee, Sang-Hyun, Kim, Jiyeon, Sim, Hasung, Morioka, T., Nojiri, H., Krishnamurthy, V. V., Manuel, P., Lees, M. R., Streltsov, S. V., Khomskii, D. I., and Park, Je-Geun

Abstract

When an electronic system has strong correlations and a large spin-orbit interaction, it often exhibits a plethora of mutually competing quantum phases. How a particular quantum ground state is selected out of several possibilities is a very interesting question. However, equally fascinating is how such a quantum entangled state breaks up due to perturbation. This important question has relevance in very diverse fields of science from strongly correlated electron physics to quantum information. Here we report that a quantum entangled dimerized state or valence bond crystal (VBC) phase of Li2RuO3 shows nontrivial doping dependence as we perturb the Ru honeycomb lattice by replacing Ru with Li. Through extensive experimental studies, we demonstrate that the VBC phase melts into a valence bond liquid phase of the RVB (resonating valence bond) type. This system offers an interesting playground where one can test and refine our current understanding of the quantum competing phases in a single compound.

Published
2016

11. Development of compression-controlled low-level laser probe system: towards clinical application.

Author

Yeo, Changmin, Yeo, Changmin, Son, Taeyoon, Park, Junghwan, Lee, Young-Heum, Kwon, Kiwoon, Nelson, J Stuart, Jung, Byungjo, Yeo, Changmin, Yeo, Changmin, Son, Taeyoon, Park, Junghwan, Lee, Young-Heum, Kwon, Kiwoon, Nelson, J Stuart, and Jung, Byungjo

Abstract

Various physico-chemical tissue optical clearing (TOC) methods have been suggested to maximize photon density in tissue. In order to enhance photon density, a compression-controlled low-level laser probe (CCLLP) system was developed by utilizing the principle of mechanical tissue compression. Negative compression (NC) was applied to the laser probes built in various diameters and simultaneously the laser was irradiated into ex-vivo porcine skin samples. Laser photon density (LPD) was evaluated as a function of NC and probe diameter by analyzing 2D diffusion images of the laser exposures. The CCLLP system resulted in a concentrated laser beam profile, which means enhancement of the LPD. As indicators of LPD, the laser peak intensity increased and the full width at half maximum (FWHM) decreased as a function of NC. The peak intensity at –30 kPa increased 2.74, 3.22, and 3.64 fold at laser probe diameters of 20, 30, and 40 mm, respectively. In addition, sample temperature was measured with a thermal camera and increased 0.4 K at –30 kPa after 60 s of laser irradiation as a result of enhanced LPD. The CCLLP system effectively demonstrated enhancement of the LPD in tissue and potentially its clinical feasibility.

Published
2010

12. Development of compression-controlled low-level laser probe system: towards clinical application.

Author

Yeo, Changmin, Yeo, Changmin, Son, Taeyoon, Park, Junghwan, Lee, Young-Heum, Kwon, Kiwoon, Nelson, J Stuart, Jung, Byungjo, Yeo, Changmin, Yeo, Changmin, Son, Taeyoon, Park, Junghwan, Lee, Young-Heum, Kwon, Kiwoon, Nelson, J Stuart, and Jung, Byungjo

Abstract

Various physico-chemical tissue optical clearing (TOC) methods have been suggested to maximize photon density in tissue. In order to enhance photon density, a compression-controlled low-level laser probe (CCLLP) system was developed by utilizing the principle of mechanical tissue compression. Negative compression (NC) was applied to the laser probes built in various diameters and simultaneously the laser was irradiated into ex-vivo porcine skin samples. Laser photon density (LPD) was evaluated as a function of NC and probe diameter by analyzing 2D diffusion images of the laser exposures. The CCLLP system resulted in a concentrated laser beam profile, which means enhancement of the LPD. As indicators of LPD, the laser peak intensity increased and the full width at half maximum (FWHM) decreased as a function of NC. The peak intensity at –30 kPa increased 2.74, 3.22, and 3.64 fold at laser probe diameters of 20, 30, and 40 mm, respectively. In addition, sample temperature was measured with a thermal camera and increased 0.4 K at –30 kPa after 60 s of laser irradiation as a result of enhanced LPD. The CCLLP system effectively demonstrated enhancement of the LPD in tissue and potentially its clinical feasibility.

Published
2010

13. Inelastic neutron scattering studies of doped CeNiSn and CeRhSb : Crystal-field excitations and origin of the pseudogap

Author

So, J.-Y., Oh, Seung June, Park, Junghwan Gahb, Adroja, D. T., McEwen, Keith A., Takabatake, Toshiro, So, J.-Y., Oh, Seung June, Park, Junghwan Gahb, Adroja, D. T., McEwen, Keith A., and Takabatake, Toshiro

Abstract

type:text, The formation of pseudogaps in CeNiSn and CeRhSb has been a puzzle for more than a decade. In order to uncover the mystery, we have undertaken inelastic neutron scattering studies of CeNi0.85Cu0.15Sn and CeRh1-xPdxSb with x=0.1 and 0.2. From this study, we have succeeded in finding two observable crystal field excitations experimentally. Our subsequent analysis using a crystalline electric field (CEF) Hamiltonian reveals that the experimental observation can be explained by two separate solutions of the CEF Hamiltonian with different ground state wave functions. Interestingly enough, these two solutions are the same ones favored by two independent theoretical models. We have made further analysis and calculations using a superposition model in order to distinguish between these two solutions and, furthermore, discuss our findings with respect to the currently available theories. Our new results shed light on the nature of the gap formation of CeNiSn and CeRhSb.

Published
2005

14. Inelastic neutron scattering studies of doped CeNiSn and CeRhSb : Crystal-field excitations and origin of the pseudogap

Author

So, J.-Y., Oh, Seung June, Park, Junghwan Gahb, Adroja, D. T., McEwen, Keith A., Takabatake, Toshiro, So, J.-Y., Oh, Seung June, Park, Junghwan Gahb, Adroja, D. T., McEwen, Keith A., and Takabatake, Toshiro

Abstract

The formation of pseudogaps in CeNiSn and CeRhSb has been a puzzle for more than a decade. In order to uncover the mystery, we have undertaken inelastic neutron scattering studies of CeNi0.85Cu0.15Sn and CeRh1-xPdxSb with x=0.1 and 0.2. From this study, we have succeeded in finding two observable crystal field excitations experimentally. Our subsequent analysis using a crystalline electric field (CEF) Hamiltonian reveals that the experimental observation can be explained by two separate solutions of the CEF Hamiltonian with different ground state wave functions. Interestingly enough, these two solutions are the same ones favored by two independent theoretical models. We have made further analysis and calculations using a superposition model in order to distinguish between these two solutions and, furthermore, discuss our findings with respect to the currently available theories. Our new results shed light on the nature of the gap formation of CeNiSn and CeRhSb.

Published
2005

15. Inelastic neutron scattering studies of doped CeNiSn and CeRhSb : Crystal-field excitations and origin of the pseudogap

Author

So, J.-Y., Oh, Seung June, Park, Junghwan Gahb, Adroja, D. T., McEwen, Keith A., Takabatake, Toshiro, So, J.-Y., Oh, Seung June, Park, Junghwan Gahb, Adroja, D. T., McEwen, Keith A., and Takabatake, Toshiro

Abstract

The formation of pseudogaps in CeNiSn and CeRhSb has been a puzzle for more than a decade. In order to uncover the mystery, we have undertaken inelastic neutron scattering studies of CeNi0.85Cu0.15Sn and CeRh1-xPdxSb with x=0.1 and 0.2. From this study, we have succeeded in finding two observable crystal field excitations experimentally. Our subsequent analysis using a crystalline electric field (CEF) Hamiltonian reveals that the experimental observation can be explained by two separate solutions of the CEF Hamiltonian with different ground state wave functions. Interestingly enough, these two solutions are the same ones favored by two independent theoretical models. We have made further analysis and calculations using a superposition model in order to distinguish between these two solutions and, furthermore, discuss our findings with respect to the currently available theories. Our new results shed light on the nature of the gap formation of CeNiSn and CeRhSb.

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