Dr. of Engineering, Kyushu University, Mar. 2022

熱活性遅延蛍光材料

有機マイクロ共振器

ポラリトン ボーズ・アインシュタイン凝縮

有機光エレクトロニクス

Exciton-Polariton

Nanotechnology/Materials, Organic functional materials, Exciton-Polariton

Nov. 2024, Fonds de Recherche du Québec Nature et technologies, FRQNT scholarship PBEEE
Bose-Einstein Condensation of Triplet Excitons in Strongly Coupled Photonic Crystals

Feb. 2023, CMC microsystems, MNT Financial Assistance Voucher
Exciton-polariton and polariton Boese-Einstein condensate in a distributed feedback resonator containing organic molecules

Nov. 2022, 日本学術振興会, JSPS 海外特別研究員
三重項励起子のアップコンバージョンを利用したBose-Einstein凝縮相の開発

Mar. 2022, 応用物理学会, JSAP Young Scientist Presentation Award
Observation of a polariton Bose-Einstein condensate in organic microcavities with BSB-Cz derivatives
石井智大

Dec. 2021, 日本学術振興会, JSPS 若手研究者海外挑戦プログラム
有機マイクロ共振器中における低閾値なBose-Einstein凝縮相の開発

Apr. 2019, 九州大学, Kyushu university scholarship

Apr. 2017, 日本学術振興会, JSPS 特別研究員DC1
原子レベルで制御したイリジウム酸化物における新奇超伝導相の創出

Apr. 2016, 日本学生支援機構, Japan Student Services Organization, Full exemption

Mar. 2015, 青山学院大学, Aoyama Gakuin Best Presentation Award

Apr. 2014, 青山学院大学, Aoyama Gakuin prize fellowship

Apr. 2013, 青山学院大学, Aoyama Gakuin scholarship

Efficient Electroluminescence from Organic Fluorophore‐Containing Perovskite Films
Toshinori Matsushima; Chuanjiang Qin; Teng Teng; Narayanaswamy Kamatham; Lydia Sosa Vargas; David Kreher; Benoit Heinrich; Tomohiro Ishii; Shinobu Terakawa; Matthew R. Leyden; Atula S. D. Sandanayaka; Fatima Bencheikh; Kiyoshi Miyata; Ken Onda; Yoshihiko Kanemitsu; Fabrice Mathevet; Chihaya Adachi
Advanced Materials, 36, 49, Wiley, 17 Oct. 2024
Scientific journal, Abstract

Two‐dimensional perovskites containing an organic fluorophore can be a unique emitter for light‐emitting diodes (LEDs). However, external quantum efficiencies (EQEs) of fluorophore‐containing perovskite LEDs reported thus far are still very low. In this study, these are able to boost the EQE to ≈10% by choosing an organic fluorophore with appropriate energy levels for the perovskite structure organization. In the fluorophore‐containing perovskite LEDs, carrier transport and exciton formation take place in the perovskite's metal halide framework, thereby avoiding the direct formation of nonradiative triplet excitons on the organic fluorophores. Subsequently, the bright triplet excitons formed in the metal halide framework are transferred to form the radiative singlet states of the organic fluorophores, leading to efficient electroluminescence (EL) from the organic fluorophores regularly dispersed inside the perovskite structure. Unexpectedly higher light‐outcoupling efficiency, which is caused by the light scattering in the polycrystalline perovskite layer, will be another reason for efficient EL. These findings will contribute toward the fabrication of LED‐based products with high performance at a low cost.

Modified Prompt and Delayed Kinetics in a Strongly Coupled Organic Microcavity Containing a Multiresonance TADF Emitter
Tomohiro Ishii; Juan B. Pérez-Sánchez; Joel Yuen-Zhou; Chihaya Adachi; Takuji Hatakeyama; Stéphane Kéna-Cohen
ACS Photonics, American Chemical Society (ACS), 10 Sep. 2024, [Peer-reviewed], [Lead author]

Artificial p–n‐like Junction Based on Pure 2D Organic–Inorganic Halide Perovskite Structure Having Naphthalene Diimide Acceptor Moieties
Zhao Feng; Xuelong Liu; Kentaro Imaoka; Tomohiro Ishii; Ganbaatar Tumen‐Ulzii; Xun Tang; George F. Harrington; Benoît Heinrich; Jean‐Charles Ribierre; Lise‐Marie Chamoreau; Lydia Sosa Vargas; David Kreher; Kenichi Goushi; Toshinori Matsushima; Guijiang Zhou; Fabrice Mathevet; Chihaya Adachi
Advanced Optical Materials, 11, 10, Wiley, 12 Mar. 2023
Scientific journal, Abstract

2D organic–inorganic perovskites are an emerging class of materials with great potential for optoelectronics since a wide variety of large functional chromophores can be regularly incorporated. Among this new type of materials, hybrid perovskite systems incorporating strong electron acceptor molecules are considered as a promising approach to designing a new type of functional 2D perovskites for optoelectronics. In this work, a rare example of organic–inorganic 2D perovskite incorporating strong acceptors such as naphthalene diimide (NDI) building blocks between inorganic sheets is presented. This hybrid architecture forms highly air‐stable thin films with a structure consisting of inorganic perovskite monolayers of metal‐halide octahedra separated by bilayers of NDI‐based organic cations. The presence of strong electron‐accepting moieties in this multifunctional donor–acceptor hybrid heterostructure leads to a rare type II heterojunction in which the excitons can be efficiently dissociated via the electron‐transfer process and in which holes and electrons can be easily confined in the inorganic and organic sublayers, respectively. Such an ultimate p–n heterojunction shows improved photoconduction properties with a photocurrent multiplied by ≈40 under white‐light illumination in comparison to a similar 2D perovskite structure containing optically and electrically inert alkyl chains as organic components.

Room-Temperature Continuous-Wave Microcavity Lasers from Solution-Processed Smooth Quasi-2D Perovskite Films with Low Thresholds
Xiang Gao; Jie Lin; Xiaoyang Guo; Geng He; Deyue Zou; Tomohiro Ishii; Dezhong Zhang; Chenyang Zhao; Hongmei Zhan; Jing Song Huang; Xingyuan Liu; Chihaya Adachi; Chuanjiang Qin; Lixiang Wang
The Journal of Physical Chemistry Letters, 14, 10, 2493, 2500, American Chemical Society (ACS), 03 Mar. 2023
Scientific journal

Efficient Perovskite Light‐Emitting Diodes with a Siloxane‐Blended Organic Hole Transport Layer
Toshinori Matsushima; Ryotaro Nasu; Kotaro Takekuma; Tomohiro Ishii; Zhao Feng; Xun Tang; Nozomi Nakamura; Ganbaatar Tumen-Ulzii; Chihaya Adachi
Advanced Photonics Research, 3, 10, Wiley, 14 May 2022
Scientific journal, Metal halide perovskite light‐emitting diodes (LEDs) are promising for future display applications because of their excellent advantages, such as high external quantum efficiency, emission color tunability, and high emission color purity. Although solution processing widely used for perovskite film fabrication is an additional advantage, there are cases in which fabricating a perovskite‐emitting layer with spin‐coating results in the dissolution of an underlying organic hole transport layer (HTL). As a result, since a perovskite layer comes into partial contact with an indium tin oxide (ITO) anode layer, excited states formed in a perovskite‐emitting layer are quenched by charge transfer to ITO. In this study, it is shown that adding tetraethyl orthosilicate (TEOS) into a HTL material of poly(N‐vinylcarbazole) (PVCz) is an effective method used to overcome this issue. Upon heating, the hydrolysis reaction of TEOS molecules takes place in PVCz films to form a siloxane network, which makes PVCz films insoluble and, therefore, alleviates the excited‐state quenching. It is demonstrated that using the siloxane‐blended PVCz HTL increases external quantum efficiencies of perovskite LEDs to 15.4 ± 0.3% from the original 10.4 ± 0.3% by about 1.5 times.

Low‐Threshold Exciton‐Polariton Condensation via Fast Polariton Relaxation in Organic Microcavities
Tomohiro Ishii; Kiyoshi Miyata; Masashi Mamada; Fatima Bencheikh; Fabrice Mathevet; Ken Onda; Stéphane Kéna‐Cohen; Chihaya Adachi
Advanced Optical Materials, 10, 3, Wiley, 29 Nov. 2021
Scientific journal, Abstract

In organic microcavities, a macroscopic condensate of exciton‐polaritons can be formed at high‐exciton polariton densities. The threshold for forming this condensate is proportional to the relaxation rate from initially excited excitons to these polaritons and the lifetime of the lowest energy polariton states. Although the influence of the lower polariton (LP) lifetime on the threshold has been studied, the relationship between the polariton relaxation rate and the threshold has not been fully explored. In this study, a room‐temperature polariton condensate is demonstrated at a threshold pump fluence of 9.7 ± 0.1 µJ cm⁻², in a microcavity containing 4,4″‐bis((E)‐4‐(3,6‐bis(2‐ethylhexyl)‐(9H‐carbazol‐9‐yl))styryl)‐1,1″‐biphenyl (BSBCz‐EH). By using a semiclassical model to describe the polariton kinetics, it is revealed that this low threshold results from the rapid relaxation rate from the dark exciton reservoir to the set of the LP states forming the condensate, with an effective rateW_ep ≈ 2.0 × 10⁻⁵cm³s⁻¹. These results show that accelerating polariton relaxation is possible and is an important factor for realizing low‐threshold polariton condensates.

Enhanced Light–Matter Interaction and Polariton Relaxation by the Control of Molecular Orientation
Tomohiro Ishii; Fatima Bencheikh; Sébastien Forget; Sébastien Chénais; Benoît Heinrich; David Kreher; Lydia Sosa Vargas; Kiyoshi Miyata; Ken Onda; Takashi Fujihara; Stéphane Kéna‐Cohen; Fabrice Mathevet; Chihaya Adachi
Advanced Optical Materials, 9, 22, Wiley, 24 Sep. 2021
Scientific journal, Abstract

Exciton‐polaritons, in which the electronic state of an excited organic molecule and a photonic state are strongly coupled, can form a Bose–Einstein condensate (BEC) at room temperature. However, so far, the reported thresholds of organic polariton BECs under optical excitation are as high asP_th = 11–500 μJ cm^–2. One route toward lowering the condensation threshold is to increase the Rabi energy by aligning the molecular transition dipole moments. In this report, it is demonstrated that control of the orientation of a perylene‐based discotic dye, which is able to self‐organize in mesogenic columnar structures, can significantly enhance exciton–photon interaction and polariton relaxation rate in optical cavities. These results show the importance of the molecular orientation for strong light–matter interactions and provide a promising strategy toward the realization of an organic low threshold polariton BEC system and electrically driven organic polariton BEC.

Modification of magnetic fluctuations by interfacial interactions in artificially engineered heavy-fermion superlattices
Genki Nakamine; Takayoshi Yamanaka; Shunsaku Kitagawa; Masahiro Naritsuka; Tomohiro Ishii; Takasada Shibauchi; Takahito Terashima; Yuichi Kasahara; Yuji Matsuda; Kenji Ishida
Physical Review B, 99, 8, American Physical Society (APS), 19 Feb. 2019
Scientific journal

Tuning the Pairing Interaction in a ��-Wave Superconductor by Paramagnons Injected through Interfaces
M. Naritsuka; P. F. S. Rosa; Yongkang Luo; Y. Kasahara; Y. Tokiwa; T. Ishii; S. Miyake; T. Terashima; T. Shibauchi; F. Ronning; J. D. Thompson; Y. Matsuda
Physical Review Letters, 120, 18, American Physical Society (APS), 04 May 2018
Scientific journal

Emergent exotic superconductivity in artificially engineered tricolor Kondo superlattices
M. Naritsuka; T. Ishii; S. Miyake; Y. Tokiwa; R. Toda; M. Shimozawa; T. Terashima; T. Shibauchi; Y. Matsuda; Y. Kasahara
Physical Review B, 96, 17, American Physical Society (APS), 16 Nov. 2017
Scientific journal

Tuning the Magnetic Quantum Criticality of Artificial Kondo Superlattices CeRhIn5/YbRhIn5
T. Ishii; R. Toda; Y. Hanaoka; Y. Tokiwa; M. Shimozawa; Y. Kasahara; R. Endo; T. Terashima; A. H. Nevidomskyy; T. Shibauchi; Y. Matsuda
Physical Review Letters, 116, 20, American Physical Society (APS), 20 May 2016
Scientific journal

Photonic Enhancement of Photoluminescence Quantum Yield beyond the Purcell Factor
T. Ishii; S. Kéna-Cohen, ICEL 2024 14th International Conference on Electroluminescence and Optoelectronic Devices, Nov. 2024, [Peer-reviewed], [Lead author]

多重共鳴効果を有するTADF材料を含んだマイクロ共振器中における励起子ポラリトンリサイクリング過程
石井 智大; Perez-Sanchez Juan B.; Yuen-Zhou Joel; 安達 千波矢; 畠山 琢次; Kena-Cohen Stephane, 2024年第71回応用物理学会春季学術講演会, Mar. 2024, [Lead author]

Radiative Pumping of Exciton-Polaritons and Polariton Disorder in Organic Microcavities
T. Ishii; F. Herrera; M. Mamada; A. Abe; M. Saigo; K. Miyata; K. Onda; F. Bencheikh; S. Kéna-Cohen; C. Adachi, 2024年第71回応用物理学会春季学術講演会, Mar. 2024, [Lead author]

Exciton-Polariton Condensation in Organic Microcavities: Polariton Radiative Relaxation Process
T. Ishii; K. Miyata; M. Mamada; A. Abe; M. Saigo; F. Bencheikh; F. Matheve; K. Onda; F. Herrera; S. Kéna-Cohen; C. Adachi, Photonics North 2023, Jun. 2023, [Corresponding author]

Exciton-Polariton Condensation in Organic Microcavities: Polariton Relaxation and Polariton Dephasing Dynamics
T. Ishii; K. Miyata; M. Mamada; A. Abe; M. Saigo; F. Bencheikh; F. Matheve; K. Onda; F. Herrera; S. Kéna-Cohen; C. Adachi, 2nd Workshop on Molecular Quantum Technology MQT 2022, Dec. 2022, [Lead author]

Relaxation from Triplet to Polaritonic States in Organic Microcavities
T. Ishii; T. Hatakeyama; C. Adachi; S. Kéna-Cohen, The 7th International TADF Workshop, Dec. 2022, [Lead author]

Radiative Pumping of Exciton-Polaritons via Phosphorescence in Organic Microcavities
T. Ishii; T. Hatakeyama; C. Adachi; S. Kéna-Cohen, MOLECULAR POLARITONICS 2022: Theoretical and Numerical Approaches, Sep. 2022, [Lead author]

Control of Exciton-Polariton and Bose-Einstein Condensate in Organic Microcavities
石井智大; 安達千波矢, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 69th, 2022, [Invited], [Lead author]

Accelerating polariton relaxation efficiency by controlling molecular orientation of liquid crystal
T. Ishii; F. Bencheikh; S. Forge; S.Chenais; B. Heinrich; D. Kreher; L. S. Vargas; K. Miyata; K. Onda; T. Fujihara; S. Kéna-Cohen; F. Matheve; C. Adachi, The 6th International TADF Workshop, Dec. 2021, [Lead author]
English

Understanding of the dynamics of Bose-Einstein condensate transition in organic microcavities with BSB-Cz derivatives
石井智大; 宮田潔志; 儘田正史; BENCHEIKH F.; MATHEVET F.; 恩田健; KENA-COHEN S.; 安達千波矢; 安達千波矢, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 82nd, 2021, [Lead author]

Observation of a polariton Bose-Einstein condensate in organic microcavities with BSB-Cz derivatives
石井智大; 宮田潔志; 儘田正史; BENCHEIKH F.; MATHEVET F.; 恩田健; KENA-COHEN S.; 安達千波矢; 安達千波矢, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 82nd, 2021, [Lead author]

Controlling of polariton relaxation dynamics by changing intramolecular charge transfer strength
Ishii Tomohiro; Mamada Masashi; Bencheikh Fatima; Miyata Kiyoshi; Onda Ken; Adachi Chihaya, JSAP Annual Meetings Extended Abstracts, 2020.2, 1541, 1541, 26 Aug. 2020, [Lead author]
The Japan Society of Applied Physics, Japanese

Acceleration of the polariton relaxation efficiency by the control of the molecular orientation
Ishii Tomohiro; Vargas Lydia; Mathevet Fabrice; Bencheikh Fatima; Miyata Kiyoshi; Onda Ken; Adachi Chihaya, JSAP Annual Meetings Extended Abstracts, 2020.2, 1540, 1540, 26 Aug. 2020, [Lead author]
The Japan Society of Applied Physics, Japanese

Observation of a polariton state in organic microcavities with BSB-Cz derivatives
Ishii Tomohiro; Mamada Masashi; Bencheikh Fatima; Miyata Kiyoshi; Onda Ken; Adachi Chihaya, JSAP Annual Meetings Extended Abstracts, 2020.1, 2290, 2290, 28 Feb. 2020, [Lead author]
The Japan Society of Applied Physics, Japanese

カイラル超伝導体におけるエッジ電流の検出に向けたMicro-SQUIDの作製
石井智大; 橋本浩法; 土師将裕; 柏谷聡; 三宅亮; 芳賀芳範; 寺嶋孝仁; 芝内孝禎; 笠原裕一; 松田祐司, 日本物理学会講演概要集(CD-ROM), 73, 1, 2018, [Lead author]

¹¹⁵In-NMR/NQRで観る人工超格子CeCoIn₅/CeRhIn₅及びエピタキシャル膜CeRhIn₅の磁気構造の層数依存性
仲嶺元輝; 山中隆義; 北川俊作; 石田憲二; 石井智大; 成塚政裕; 鳥井陽平; 下澤雅明; 宍戸寛明; 宍戸寛明; 笠原成; 常盤欣文; 笠原裕一; 水上雄太; 芝内孝禎; 寺嶋孝仁; 松田祐司, 日本物理学会講演概要集(CD-ROM), 73, 1, 2018

人工超格子CeCoIn₅/YbCoIn₅とCeCoIn₅/CeRhIn₅のNMR
仲嶺元輝; 山中隆義; 北川俊作; 石田憲二; 石井智大; 成塚政裕; 鳥井陽平; 下澤雅明; 宍戸寛明; 宍戸寛明; 笠原成; 常盤欣文; 笠原裕一; 水上雄太; 芝内孝禎; 寺嶋孝仁; 松田祐司, 京都大学物性科学センター誌, 32, 2018

CeRhIn₅/CeCoIn₅ハイブリッド超格子における圧力下強結合超伝導状態の実現
成塚政裕; 石井智大; 三宅聡平; 下澤雅明; 芝内孝禎; 常盤欣文; ROSA P.F.S.; LUO Y.; RONNING F.; THOMPSON J.D.; 笠原裕一; 寺嶋孝仁; 松田祐司, 日本物理学会講演概要集(CD-ROM), 72, 1, 2017

層数制御したCeCoIn₅/CeRhIn₅ハイブリッド超格子における超伝導と磁性
三宅聡平; 石井智大; 成塚政裕; 鳥井陽平; 下澤雅明; 笠原成; 笠原裕一; 芝内孝禎; 寺嶋孝仁; 松田祐司, 日本物理学会講演概要集(CD-ROM), 72, 1, 2017

トリコロール近藤超格子におけるエキゾチック超伝導相
石井智大; 成塚政裕; 三宅聡平; 下澤雅明; 笠原成; 笠原裕一; 芝内孝禎; 寺嶋孝仁; 石田憲二; 松田祐司, 日本物理学会講演概要集(CD-ROM), 72, 1, 2017, [Lead author]

重い電子系CeCoIn₅/CeRhIn₅ハイブリッド超格子の圧力下における上部臨界磁場精密角度依存性
成塚政裕; 石井智大; 三宅聡平; 下澤雅明; 芝内孝禎; 常盤欣文; 常盤欣文; ROSA P. F. S.; LUO Y.; RONNING F.; THOMPSON J. D.; 笠原裕一; 寺嶋孝仁; 松田祐司, 日本物理学会講演概要集(CD-ROM), 72, 2, 2017

NMR/NQRによる重い電子系人工超格子CeCoIn₅/CeRhIn₅及びCeRhIn₅単結晶膜の磁気状態の研究
仲嶺元輝; 山中隆義; 北川俊作; 石田憲二; 石井智大; 成塚政裕; 鳥井陽平; 下澤雅明; 宍戸寛明; 宍戸寛明; 笠原成; 常盤欣文; 笠原裕一; 水上雄太; 芝内孝禎; 寺嶋孝仁; 松田祐司, 日本物理学会講演概要集(CD-ROM), 72, 2, 2017

重い電子系CeCoIn₅/CeIn₃ヘテロ構造の超伝導状態
三宅聡平; 石井智大; 成塚政裕; 笠原裕一; 下澤雅明; 芝内孝禎; 寺嶋孝仁; 松田祐司, 日本物理学会講演概要集(CD-ROM), 72, 2, 2017

近藤超格子CeRhIn₅/YbRhIn₅における磁気量子臨界性の次元性制御
石井智大; 戸田琳太郎; 花岡洋祐; 常盤欣文; 下澤雅明; 笠原裕一; 寺嶋孝仁; NEVIDDOMSKY A. H.; 芝内孝禎; 松田祐司, 京都大学物性科学センター誌, 30, 2017, [Lead author]

CeCoIn₅系トリコロール超格子によるPauli対破壊効果の人工制御
三宅聡平; 石井智大; 成塚政裕; 鳥井陽平; 笠原成; 常盤欣文; 笠原裕一; 寺嶋孝仁; 石田憲二; 松田祐司; 芝内孝禎; 下澤雅明, 京都大学物性科学センター誌, 30, 2017

CeCoIn₅/CeRhIn₅ハイブリッド超格子における超強結合超伝導
成塚政裕; 石井智大; 鳥井陽平; 三宅聡平; 常盤欣文; 常盤欣文; 下澤雅明; 芝内孝禎; ROSA P. F. S.; LUO Y.; RONNING F.; THOMPSON J. D.; 笠原裕一; 寺嶋孝仁; 松田祐司, 京都大学物性科学センター誌, 30, 2017

Comparison between CeCoIn₅/CeRhIn₅ and CeCoIn₅/YbCoIn₅ by ⁵⁹Co-NMR
Nakamine G.; Yamanaka T.; Kitagawa S.; Ishida K.; Ishii T.; Naritsuka M.; Torii Y.; Shimozawa M.; Shishido H.; Kasahara S.; Tokiwa Y.; Kasahara Y.; Mizukami Y.; Shibauchi T.; Terashima T.; Matsuda Y., Meeting Abstracts of the Physical Society of Japan, 72.1, 1964, 1964, 2017
近年、京都大学の松田・寺嶋グループにより重い電子系の人工超格子が作成され興味を集めている。この人工超格子では、重い電子系超伝導の２次元化や、界面での近接効果などの興味深い現象が期待できるだけでなく、化合物の組み合わせという自由度も加わり新たな強相関電子系の研究の場を提供したといえる。我々は、微視的測定手段であるNMRを用いて、人工超格子の各ブロック層の電子状態を調べている。今回人工超格子CeCoIn_5_/ CeRhIn_5_とCeCoIn_5_/ YbCoIn_5_の物性の違いについて、CeCoIn_5_層に注目して研究を行った。, The Physical Society of Japan, Japanese

ハイブリッド超格子CeCoIn₅/CeRhIn₅における超伝導特性
鳥井陽平; 石井智大; 戸田琳太郎; 成塚政裕; 下澤雅明; 花岡洋祐; 笠原成; 常盤欣文; 笠原裕一; 芝内孝禎; 寺嶋孝仁; 松田祐司, 日本物理学会講演概要集(CD-ROM), 71, 1, 2016

ハイブリッド超格子CeCoIn₅/CeRhIn₅における量子臨界性
石井智大; 鳥井陽平; 戸田琳太郎; 成塚政裕; 下澤雅明; 花岡洋祐; 笠原成; 常盤欣文; 笠原裕一; 芝内孝禎; 寺嶋孝仁; 松田祐司, 日本物理学会講演概要集(CD-ROM), 71, 1, 2016, [Lead author]

CeRhIn₅/CeCoIn₅ハイブリッド超格子における圧力下強結合超伝導状態の実現
成塚政裕; LUO Y.; ROSA P.F.S.; 石井智大; 鳥井陽平; RONNING F.; BAUER E.D.; THOMPSON J.D.; MOVSHOVICH R.; 下澤雅明; 笠原成; 常盤欣文; 笠原裕一; 芝内孝禎; 寺嶋孝仁; 松田祐司, 日本物理学会講演概要集(CD-ROM), 71, 2, 2016

CeCoIn₅系トリコロール超格子によるPauli対破壊効果の人工制御
三宅聡平; 石井智大; 成塚政裕; 鳥井陽平; 下澤雅明; 笠原成; 常盤欣文; 笠原裕一; 芝内孝禎; 寺嶋孝仁; 石田憲二; 松田祐司, 日本物理学会講演概要集(CD-ROM), 71, 2, 2016

重い電子系ハイブリッド超格子CeRhIn₅/CeCoIn₅における輸送特性
石井智大; 戸田琳太郎; 鳥井陽平; 成塚政裕; 下澤雅明; 笠原成; 常盤欣文; 笠原裕一; 芝内孝禎; 寺嶋孝仁; 松田祐司, 京都大学物性科学センター誌, 28, 2016, [Lead author]

NMR study of heavy-fermion superconducting CeCoIn₅ / Antiferromagnetic CeRhIn₅ superlattice
Nakamine G.; Yamanaka T.; Kitagawa S.; Ishida K.; Ishii T.; Naritsuka M.; Torii Y.; Shimozawa M.; Kasahara S.; Tokiwa Y.; Kasahara Y.; Shibauchi T.; Terashima T.; Matsuda Y., Meeting Abstracts of the Physical Society of Japan, 71.2, 2076, 2076, 2016
近年、京都大学の松田・寺嶋グループにより重い電子系の人工超格子が作成され興味を集めている。この人工超格子では、重い電子系超伝導の2次元化や、界面での近接効果などの興味深い現象が期待できるだけでなく、化合物の組み合わせという自由度も加わり新たな強相関電子系の研究の場を提供したといえる。また我々は、微視的測定手段であるNMRを用いて、人工超格子の各ブロック層の電子状態を調べている。今回重い電子系超伝導体と重い電子系反強磁性体からなるCeCoIn_5_/ CeRhIn_5_人工超格子の超伝導のCeCoIn_5_層に注目して研究を行った。発表ではその詳細を報告する。, The Physical Society of Japan, Japanese

CeCoIn₅系トリコロール超格子によるグローバルな空間反転対称性の破れの導入
成塚政裕; 遠藤僚太; 戸田琳太郎; 石井智大; 下澤雅明; 花岡洋祐; 笠原成; 常盤欣文; 笠原裕一; 芝内孝禎; 寺嶋孝仁; 松田祐司, 日本物理学会講演概要集(CD-ROM), 70, 2, 2015

重い電子系ハイブリッド超格子CeRhIn₅/CeCoIn₅における輸送測定
石井智大; 遠藤僚太; 戸田琳太郎; 成塚政裕; 下澤雅明; 花岡洋祐; 笠原成; 常盤欣文; 笠原裕一; 芝内孝禎; 寺嶋孝仁; 松田祐司, 日本物理学会講演概要集(CD-ROM), 70, 2, 2015, [Lead author]

Polariton Chemistry: Molecules in Cavities
Tomohiro Ishii; Stéphane Kéna-Cohen; Felipe Herrera; Chihaya Adachi, Chapter11
Wiley, May 2025, [Contributor]

有機半導体の開発と最新動向
石井智大; Stéphane Kéna-Cohen, 第32章
シーエムシー出版, Mar. 2024, 9784781317632, xii, 400p, Japanese, [Contributor]

Low-threshold exciton-polariton condensate via fast polariton relaxation in organic microcavities
T. Ishii; K. Miyata; M. Mamada; F. Bencheikh; F. Matheve; K. Onda; S. Kéna-Cohen; C. Adachi
APS March Meeting 2022, English
14 Mar. 2022 - 18 Mar. 2022

Tuning the Magnetic Quantum Criticality of Artificial Kondo Superlattices CeRhIn5/YbRhIn5
T. Ishii; R. Toda; Y. Hanaoka; Y. Tokiwa; M. Shimozawa; Y. Kasahara; R. Endo; T. Terashima; A. H. Nevidomskyy; T. Shibauchi; Y. Matsuda
Quantum Criticality and Topology in Itinerant Electron Systems, Poster presentation
19 Aug. 2016

2021 - Present
分子科学討論会

Mar. 2020 - Present
応用物理学会

Apr. 2015 - Dec. 2017
物理学会

Bose-Einstein Condensation of Triplet Excitons in Strongly Coupled Photonic Crystals
PBEEE / Postdoctoral research fellow
Apr. 2024 - Mar. 2025
CANADA FRQNT, 有機エレクトロニクス, Polytechnique Montreal

Development of Bose=Einstein condensate phase using spin-triplet upconversion
海外特別研究員
Apr. 2022 - Mar. 2024
Japan Society for the Promotion of Science, 有機エレクトロニクス, Polytechnique Montreal, Principal investigator

Exciton-polariton and polariton Boese-Einstein condensate in a distributed feedback resonator containing organic molecules
MNT Financial Assistance Voucher
Feb. 2023 - Jun. 2023
CMC microsystems, 有機エレクトロニクス, Polytechnique Montreal

Development of low-threshold Bose-Einstein condensation in organic microcavities
若手研究者海外挑戦プログラム
Apr. 2021 - Mar. 2022
Japan Society for the Promotion of Science, 有機エレクトロニクス, Polytechnique Montreal

原子レベルで制御したイリジウム酸化物における新奇超伝導相の創出
科学研究費助成事業
26 Apr. 2017 - 31 Mar. 2020
石井 智大
本年度は(1)トリコロール近藤超格子によるエキゾチック超伝導相の創出(2)カイラル超伝導体のエッジ電流の検出に向けたMicro-SQUIDの作製(3)酸化物分子線エピタキシー装置の立ち上げの3点に関する研究を行った。各々の研究実績の詳細について説明する。
(1)d波超伝導体CeCoIn5(n = 5, 7層)と非磁性金属化合物YbCoIn5(3層)、及びYbRhIn5(3層)の3物質を交互積層させたトリコロール近藤超格子を分子線エピタキシー装置により作製し、グローバルな空間反転対称性の破れと超伝導の関連性について評価を行った。その結果、上部臨界磁場の温度依存性と角度依存性からCeCoIn5のパウリ対破壊効果が強く抑制されていることを明らかにした。更にHc2に変曲点が存在することを確認し、ヘリカルもしくはストライプ超伝導などのエキゾチック超伝導相が実現している可能性を示した。
(2)カイラル超伝導体におけるカイラルエッジ電流を検出するために、Nb薄膜を用いてMicro-SQUIDの作製を行い、その素子の動作確認を行った。その結果、IV測定によりSIS接合に由来したJosephson電流の観測に成功し、更にMicro-SQUIDのリンク幅を変化させることでJosephson電流の臨界電流値が制御可能であることも明らかにした。今後は磁場中におけるMicro-SQUIDの動作性能を向上させ、URu2Si2の低温化における磁化測定を行うことを計画している。
(3)酸化物の薄膜や人工超格子の作製に必要な酸化物分子線エピタキシー装置の立ち上げ及びルテニウム酸化物Sr2RuO4薄膜の作製を試みた。その結果、蒸着中に周期的なRHEED振動を確認し、薄膜X線構造解析からc軸方向への高い配向性を有することを明らかにし、Sr2RuO4のエピタキシャル薄膜の成膜に成功した。
日本学術振興会, 特別研究員奨励費, 京都大学, 17J03863