研究者詳細 - 鄭　国慶

論文 - 鄭　国慶

分割表示 265 件中 1 - 20 件目／全件表示 >>

Antiferromagnetic Spin Fluctuations and Unconventional Superconductivity in Topological Superconductor Candidate YPtBi Revealed by 195Pt-NMR 査読

Y. Z. Zhou, J. Chen, Z. X. Li, J. Luo, J. Yang, Y. F. Guo, W. H. Wang, R. Zhou, Guo-qing Zheng

Physical Review Letters 130 ( 26 ) 2023年6月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：American Physical Society (APS)

DOI： 10.1103/physrevlett.130.266002

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その他リンク： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevLett.130.266002/fulltext

Superconducting Transition in Quasi-One-Dimensional Superconductor Cs₂Cr₃As₃ Probed by DC Magnetic Susceptibility 査読

Akihiko Sumiyama, Takumi Nagaeki, Akira Yamaguchi, Ke Jia, Jie Yang, Youguo Shi, Guo-qing Zheng

Journal of the Physical Society of Japan 92 ( 1 ) 015001(1) - 015001(2) 2023年1月

Possible star-of-David pattern charge density wave with additional modulation in the kagome superconductor CsV3Sb5 査読

J. Luo, Z. Zhao, Y. Z. Zhou, J. Yang, A. F. Fang, H. T. Yang, H. J. Gao, R. Zhou, Guo-qing Zheng

npj Quantum Materials 7 ( 1 ) 3(1) - 30(9) 2022年3月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

Abstract

AV₃Sb₅ (A = K, Rb, Cs) is a novel kagome superconductor coexisting with the charge density wave (CDW) order. Identifying the structure of the CDW order is crucial for understanding the exotic normal state and superconductivity in this system. Here, we report ⁵¹V nuclear magnetic resonance (NMR) and ^121/123Sb nuclear quadrupole resonance (NQR) studies on kagome-metal CsV₃Sb₅. Below the CDW transition temperature T_CDW ~ 98 K, an abrupt change of spectra was observed, indicating that the transition is of the first order. By further analyzing the spectra, we find that the CDW order is commensurate. And most remarkably, the obtained experimental results suggest that the charge modulation of the CDW order is of star-of-David pattern and accompanied by an additional charge modulation in bulk below T^* ~ 40 K. Our results revealing the unconventional CDW order provide new insights into AV₃Sb₅.

DOI： 10.1038/s41535-022-00437-7

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その他リンク： https://www.nature.com/articles/s41535-022-00437-7

Spin-triplet superconductivity in K 2 Cr 3 As 3 査読

Jie Yang, Jun Luo, Changjiang Yi, Youguo Shi, Yi Zhou, Guo-qing Zheng

Science Advances 7 ( 52 ) eabl4432 2021年12月

Spin-triplet superconductivity in K2Cr3As3 査読国際共著

7 ( 50 ) eabl4432 2021年12月

Antiferromagnetic spin fluctuations and superconductivity in NbRh2B2 and TaRh2B2 with a chiral crystal structure 査読

Kazuaki Matano, Ryo Ogura, Mateo Fountaine , Harald O. Jeschke , Shinji Kawasaki, and Guo-qing Zheng

PHYSICAL REVIEW B 104 22450(1) - 22450(8) 2021年12月

放射光を用いた一軸応力下構造解析の試み査読

小林映斗, 二田晴也, 佃菜桜, 峰明日香, 西垣颯, 横山武蔵, 吉田翔伍, 俣野和明, 川崎慎司, 石井賢司, 鄭国慶

SPring-8/SACLA 利用研究成果集 12 ( 5 ) 325 - 328 2024年10月

Strain-induced long-range charge-density wave order in the optimally doped Bi2Sr2−xLaxCuO6 superconductor 査読

Shinji Kawasaki, Nao Tsukuda, Chengtian Lin, Guo-qing Zheng

Nature Communications 15 ( 1 ) 5082(1) - 5082(10) 2024年6月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

Abstract

The mechanism of high-temperature superconductivity in copper oxides (cuprate) remains elusive, with the pseudogap phase considered a potential factor. Recent attention has focused on a long-range symmetry-broken charge-density wave (CDW) order in the underdoped regime, induced by strong magnetic fields. Here by ^63,65Cu-nuclear magnetic resonance, we report the discovery of a long-range CDW order in the optimally doped Bi₂Sr_2−xLa_xCuO₆ superconductor, induced by in-plane strain exceeding ∣ε∣ = 0.15 %, which deliberately breaks the crystal symmetry of the CuO₂ plane. We find that compressive/tensile strains reduce superconductivity but enhance CDW, leaving superconductivity to coexist with CDW. The findings show that a long-range CDW order is an underlying hidden order in the pseudogap state, not limited to the underdoped regime, becoming apparent under strain. Our result sheds light on the intertwining of various orders in the cuprates.

DOI： 10.1038/s41467-024-49225-w

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その他リンク： https://www.nature.com/articles/s41467-024-49225-w

High temperature spin-triplet topological superconductivity in K₂Cr₃As₃ 招待査読

Guo-qing Zheng

Journal of Physics: Conference Series 2545 ( 1 ) 012001(1) - 012001(7) 2023年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IOP Publishing

Abstract

Spin-triplet superconductors are novel materials capable of harboring Majorana bound states that can be used in topological quantum computing. However, such bulk materials are still rare. Here we review the results that established K₂Cr₃As₃ as a spin-triplet superconductor with transition temperature T_c as high as 6.5 K. We focus on the multiple-phases feature, and its exquisite distance to a ferromagnetic quantum critical point which is likely responsible for the high T_c. We touch on the topological aspects of the superconducting state, and suggest that it is a new route to the technical implementation using a topological spin-triplet superconductor at the highest temperature ever.

DOI： 10.1088/1742-6596/2545/1/012001

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その他リンク： https://iopscience.iop.org/article/10.1088/1742-6596/2545/1/012001/pdf

Single Crystal Growth of and Hyperfine Couplings in the Spin-Triplet Superconductor K₂Cr₃As₃ 査読

Seigo Ogawa, Tomoki Miyoshi, Kazuaki Matano, Shinji Kawasaki, Yoshihiko Inada, Guo-qing Zheng

Journal of the Physical Society of Japan 92 ( 6 ) 2023年6月

Commensurate-to-incommensurate transition of charge-density-wave order and a possible quantum critical point in pressurized kagome metal CsV3Sb5 査読

X. Y. Feng, Z. Zhao, J. Luo, J. Yang, A. F. Fang, H. T. Yang, H. J. Gao, R. Zhou, Guo-qing Zheng

npj Quantum Materials 8 ( 1 ) 2023年5月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

Abstract

Clarifying the interplay between charge-density waves (CDWs) and superconductivity is important in the kagome metal CsV₃Sb₅, and pressure (P) can play a crucial role. Here, we present ^121/123Sb nuclear quadrupole resonance (NQR) measurements under hydrostatic pressures up to 2.43 GPa in CsV₃Sb₅ single crystals. We demonstrate that the CDW gradually changes from a commensurate modulation with a star-of-David (SoD) pattern to an incommensurate one with a superimposed SoD and Tri-hexagonal (TrH) pattern stacking along the c-axis. Moreover, the linewidth δν of ^121/123Sb-NQR spectra increases with cooling down to T_CDW, indicating the appearance of a short-range CDW order due to CDW fluctuations pinned by quenched disorders. The δν shows a Curie–Weiss temperature dependence and tends to diverge at P_c ~ 1.9 GPa, suggesting that a CDW quantum critical point (QCP) exists at P_c where T_c shows the maximum. For P > P_c, spin fluctuations are enhanced when the CDW is suppressed. Our results suggest that the maximal T_c at P_c ~ 1.9 GPa is related to the CDW QCP, and the presence of spin fluctuations prevents the T_c from a rapid decrease otherwise, after the CDW is completely suppressed.

DOI： 10.1038/s41535-023-00555-w

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その他リンク： https://www.nature.com/articles/s41535-023-00555-w

Manipulating the nematic director by magnetic fields in the spin-triplet superconducting state of CuxBi2Se3 査読

M. Yokoyama, H. Nishigaki, S. Ogawa, S. Nita, H. Shiokawa, K. Matano, Guo-qing Zheng

Physical Review B 107 ( 10 ) 2023年3月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：American Physical Society (APS)

DOI： 10.1103/physrevb.107.l100505

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その他リンク： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevB.107.L100505/fulltext

ワイル半金属における軌道反磁性と低エネルギー励起招待査読

俣野和明, 鄭国慶, Rui Zhou

固体物理 58 ( 1 ) 31 - 38 2023年1月

Antiferromagnetic spin fluctuations and superconductivity in NbRh2B2 and TaRh2B2 with a chiral crystal structure 査読

Kazuaki Matano, Ryo Ogura, Mateo Fountaine, Harald O. Jeschke, Shinji Kawasaki, Guo-qing Zheng

Physical Review B 104 ( 22 ) 224508(1) - 224508(8) 2021年12月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：American Physical Society (APS)

DOI： 10.1103/physrevb.104.224508

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その他リンク： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevB.104.224508/fulltext

Charge Order and Fluctuations in Bi2Sr2−xLaxCuO6+δ Revealed by 63,65Cu-Nuclear Magnetic Resonance 招待査読

Shinji Kawasaki, Madoka Ito, Dai Kamijima, Chengtian Lin, Guo-qing Zheng

Journal of the Physical Society of Japan 90 111008(1) - 111008(11) 2021年8月

Transport signatures of the pseudogap critical point in the cuprate superconductor Bi2Sr2−xLaxCuO6+δ 査読

M. Lizaire, A. Legros, A. Gourgout, S. Benhabib, S. Badoux, F. Laliberté, M.-E. Boulanger, A. Ataei, G. Grissonnanche, D. LeBoeuf, S. Licciardello, S. Wiedmann, S. Ono, H. Raffy, S. Kawasaki, G.-Q. Zheng, N. Doiron-Leyraud, C. Proust, L. Taillefer

PHYSICAL REVIEW B 104 014515(1) - 014515(11) 2021年7月

Normal state specific heat in the cuprate superconductors La2-xSrxCuO4 and Bi2+ySr2-x-yLaxCuO6+δ near the critical point of the pseudogap phase 査読

C. Girod, D. Leboeuf, A. Demuer, G. Seyfarth, S. Imajo, K. Kindo, Y. Kohama, M. Lizaire, A. Legros, A. Gourgout, H. Takagi, T. Kurosawa, M. Oda, N. Momono, J. Chang, S. Ono, G. Q. Zheng, C. Marcenat, L. Taillefer, T. Klein

Physical Review B 103 ( 21 ) 2021年6月

掲載種別：研究論文（学術雑誌）

The specific heat C of the cuprate superconductors La2-xSrxCuO4 and Bi2+ySr2-x-yLaxCuO6+δ was measured at low temperatures (down to 0.5 K) for dopings p close to p∗, the critical doping for the onset of the pseudogap phase. A magnetic field up to 35 T was applied to suppress superconductivity, giving direct access to the normal state at low temperatures, and enabling a determination of Ce, the electronic contribution to the normal-state specific heat at T→0. In La2-xSrxCuO4 at x=p=0.22, 0.24 and 0.25, Ce/T=15to16mJmol-1K-2 at T=2K, values that are twice as large as those measured at higher doping (p>0.3) and lower doping (p<0.15). This confirms the presence of a broad peak in the doping dependence of Ce at p∗≃0.19 as previously reported for samples in which superconductivity was destroyed by Zn impurities. Moreover, at those three dopings, we find a logarithmic growth as T→0 such that Ce/T∼Bln(T0/T). The peak versus p and the logarithmic dependence versus T are the two typical thermodynamic signatures of quantum criticality. In the very different cuprate Bi2+ySr2-x-yLaxCuO6+δ, we again find that Ce/T∼Bln(T0/T) at p≃p∗, strong evidence that this ln(1/T) dependence of the electronic specific heat - first discovered in the cuprates La1.8-xEu0.2SrxCuO4 and La1.6-xNd0.4SrxCuO4 - is a universal property of the pseudogap critical point.

DOI： 10.1103/PhysRevB.103.214506

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Microscopic evidence for an intra-unit-cell electronic nematicity inside the pseudogap phase in YBa2Cu4O8 査読

W. Wang, J. Luo, C. G. Wang, J. Yang, Y. Kodama, R. Zhou, Guo-qing Zheng

SCIENCE CHINA Physics, Mechanics & Astronomy 63 ( 3 ) 237413 2021年1月

Nodal superconducting gap in LiFeP revealed by NMR: Contrast with LiFeAs 査読

A F Fang, R Zhou, H Tukada, J Yang, Z Deng, X C Wang, C Q Jin, Guo-Qing Zheng

Chin. Phys. B 30 047403 2021年1月

Localized-to-itinerant transition preceding antiferromagnetic quantum critical point and gapless superconductivity in CeRh0.5Ir0.5In5 査読

Shinji Kawasaki, Toshihide Oka, Akira Sorime, Yuji Kogame, Kazuhiro Uemoto, Kazuaki Matano, Jing Guo, Shu Cai, Liling Sun, John L. Sarrao, Joe D. Thompson, Guo-qing Zheng

COMMUNICATIONS PHYSICS 3 ( 1 ) 2020年8月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NATURE PUBLISHING GROUP

A fundamental problem posed from the study of correlated electron compounds, of which heavy-fermion systems are prototypes, is the need to understand the physics of states near a quantum critical point (QCP). At a QCP, magnetic order is suppressed continuously to zero temperature and unconventional superconductivity often appears. Here, we report pressure T-c. (P)-dependent In-115 nuclear quadrupole resonance (NQR) measurements on heavy-fermion antiferromagnet CeRh0.5Ir0.5In5. These experiments reveal an antiferromagnetic (AF) QCP at P-c(AF) = 1.2 GPa where a dome of superconductivity reaches a maximum transition temperature Tc. Preceding P-c(AF), however, the NQR frequency nu(Q) undergoes an abrupt increase at P-c* = 0.8 GPa in the zero-temperature limit, indicating a change from localized to itinerant character of cerium's f-electron and associated small-to-large change in the Fermi surface. At P-c(AF) where T-c is optimized, there is an unusually large fraction of gapless excitations well below T-c that implicates spin-singlet, odd-frequency pairing symmetry.

DOI： 10.1038/s42005-020-00418-x

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