English / Japanese

永井佑紀

東京大学情報基盤センター学際情報科学研究部門 准教授


連絡先
Email: Nagai.Yuki_-at.-mark.-_mail.u-tokyo.ac.jp ("_"で囲まれた部分を取り去ってください)


略歴

2001 私立札幌光星高校卒業

2005 北海道大学工学部応用物理学科卒業 (物性物理工学分野:明楽浩史教授)

2007 東京大学大学院理学系研究科物理学専攻修士課程修了 (加藤雄介助教授)

2010 東京大学大学院理学系研究科物理学専攻博士課程修了 (加藤雄介准教授)

学位:博士(理学)


職歴等
2005年度夏学期: 物理学B(力学)TA
2006年度冬学期: 基礎物理学実験TA
2007年5月16日〜6月15日: 京都大学基礎物理学研究所アトム型研究員
2007年4月〜2008年3月: 理化学研究所古崎物性理論研究室JRA(ジュニア・リサーチ・アソシエイト)
2007年度冬学期: 基礎物理学実験TA(回数は半分)
2008年4月〜 日本学術振興会特別研究員(DC2)
2008年度冬学期: 基礎物理学実験TA(回数は半分)
2009年度冬学期: 基礎物理学実験TA(回数は半分)
2009年度冬学期: 英語ALESS Program 実験相談会TA
2016年11月〜2017年10月: 客員研究員(Visiting Scholar), Department of Physics, Massachusetts Institute of Technology, USA (Host reseacher: Prof. Liang Fu)
2010年4月〜2019年6月: 国立研究開発法人日本原子力研究開発機構 システム計算科学センター シミュレーション技術開発室 研究員
2018年8月〜2023年3月: 国立研究開発法人理化学研究所 革新知能統合研究センター 数理科学チーム 客員研究員
2019年7月〜2024年1月: 国立研究開発法人日本原子力研究開発機構 システム計算科学センター シミュレーション技術開発室 副主任研究員
2019年4月〜2020年3月: 学習院大学物理学科 非常勤講師 (担当講義: 熱学および統計力学2 物3年 (第一学期) および 熱学および統計力学3 物3年 (第二学期))
2020年4月〜: 学習院大学物理学科 非常勤講師 (担当講義: 物性物理学3 物3年 (第一学期))
2024年1月〜: 現職

専門
物性理論、特に固体物理

受賞等
2015年3月: 第9回(2015年)日本物理学会若手奨励賞受賞(領域6)
[LINK]
2018年10月: 日本原子力研究開発機構 理事長表彰 研究開発功績賞

これまでやってきたこと。括弧内は主な共同研究者
量子Hall系(2004年):
整数量子Hall系のホールバーの電子流体解析(北大工明楽教授)
超伝導の準古典理論による研究(2005年~)(東大総合文化加藤准教授、阪府大林講師):
渦糸電子状態(走査型トンネル顕微鏡実験の解析)、磁場回転比熱・熱伝導率の解析
多軌道系超伝導体(鉄系超伝導体)の現象論(2009年~)(東大総合文化加藤准教授、阪府大林講師、東大理青木教授、電通大黒木教授、原子力機構町田氏):
NMRによる核磁気緩和率の解析、超流動密度の解析、界面束縛状態、渦糸近傍の準粒子干渉効果の理論、 不純物による転移温度の減少の解析、中性子散乱実験の多軌道乱雑位相近似による解析
トポロジカル絶縁体の電子物性(2008年~2009年)(理研古崎氏):
スピン軌道相互作用を入れたダイヤモンド型格子の強束縛模型のAnderson転移の転送行列法による解析(残念ながら結果出ず)
超固体(2009年~)(東大総合文化加藤准教授、國見氏):
一次元有限距離グロスピタエフスキー方程式によるジョセフソン効果
グラフェンナノリボンの電子物性(2008年~2009年)(東大総合文化吉岡教授、中倉氏):
再帰的Green関数法によるグラフェンナノリボンの電子物性の計算
超伝導グラフェンの超伝導渦糸状態(2009年~2010年)(東大総合文化加藤准教授、根本氏):
Dirac-Bogoliubov-de Gennes方程式による解析計算と数値計算

これからやりたいこと、興味のあること。
上に述べた研究の発展的内容、動的平均場理論、連続時間量子モンテカルロ法、平均場方程式の直交多項式展開による解法、トポロジカル絶縁体、グラフェン、機械学習と物理学



著書

1. 永井佑紀 (著), 涌井 貞美 (著), 現代用語の基礎知識 (編さん)
理科のおさらい物理 (おとなの楽習 5
自由国民社
[Amazon]

2. 門脇 和男(編)
超伝導磁束状態の物理
裳華房
2章6.5節「BdG方程式による非一様な多バンド超伝導の理論」を執筆。
[Amazon]

3. 橋本 幸士 (著), 大槻 東巳 (著), 真野 智裕 (著), 斎藤 弘樹 (著), 藤田 浩之 (著), 安藤 康伸 (著), 永井 佑紀 (著), 青木 健一 (著), 藤田 達大 (著), 小林 玉青 (著), 大関 真之 (著), 久良 尚任 (著), 福嶋 健二 (著), 村瀬 功一 (著), 船井 正太郎 (著), 柏 浩司 (著), 富谷 昭夫 (著), 橋本 幸士 (編集)
物理学者,機械学習を使う ー機械学習・深層学習の物理学への応用ー
朝倉書店
第5章「自己学習モンテカルロ法」を執筆。
[Amazon]

4. 永井 佑紀 (著)
1週間で学べる! Julia数値計算プログラミング (KS情報科学専門書)
講談社
[Amazon]

Preprints

  1. Akio Tomiya, Yuki Nagai, Gauge covariant neural network for 4 dimensional non-abelian gauge theory, hep-lat/arXiv:2103.11965
  2. Yuki Nagai, Akio Tomiya, Extensively parallelizable chiral fermion, hep-lat/arXiv:2204.01583
  3. Yuki Nagai, Yutaka Iwasaki, Koichi Kitahara, Yoshiki Takagiwa, Kaoru Kimura, Motoyuki Shiga, Atomic diffusion due to hyperatomic fluctuation for quasicrystals, cond-mat/2302.14441
  4. Yuki Nagai, Akio Tomiya, Self-learning Monte Carlo with equivariant Transformer, cond-mat/arXiv:2306.11527
  5. Yuita Fujisawa, Anjana Krishnadas, Barnaby R. M. Smith, Markel Pardo-Almanza, Hoshu Hiyane, Yuki Nagai, Tadashi Machida, Yoshinori Okada, Imaging Josephson Vortices on Curved Junctions, cond-mat/arXiv:2307.11970
  6. Yuita Fujisawa, Anjana Krishnadas, Chia-Hsiu Hsu, Barnaby R. M. Smith, Markel Pardo-Almanza, Yukiko Obata, Dyon van Dinter, Guoqing Chang, Yuki Nagai, Tadashi Machida, Yoshinori Okada, Visualizing magnetic field-induced rotational electronic symmetry breaking in a spinel oxide superconductor, cond-mat/arXiv:2306.06711

原著論文(古い年次順で記載)

  1. Y. Nagai, Y. Kato and N. Hayashi, Analytical Result on Electronic States around a Vortex Core in a Noncentrosymmetric Superconductor, J. Phys. Soc. Jpn. 75 043706-1 043706-4 (2006) DOI: 10.1143/JPSJ.75.043706
  2. Y. Nagai, Y. Ueno, Y. Kato and N. Hayashi, Analytical Formulation of the Local Density of States around a Vortex Core in Unconventional Superconductors, J. Phys. Soc. Jpn. 75 104701-1 104701-14 (2006) DOI: 10.1143/JPSJ.75.104701
  3. Y. Nagai, Y. Kato, N. Hayashi, K. Yamauchi and H. Harima, Calculated Positions of Point Nodes in the Gap Structure of the Borocarbide Superconductor YNi2B2C, Phys. Rev. B 76, 214514-1 214514-8 (2007) DOI: 10.1103/PhysRevB.76.214514
  4. Y. Nagai and N. Hayashi, Kramer-Pesch approximation for analyzing field-angle-resolved measurements made in unconventional superconductors: A calculation of the zero-energy density of states, Phys. Rev. Lett. 101 097001-1 097001-4 (2008) DOI: 10.1103/PhysRevLett.101.097001
  5. Y. Nagai, N. Hayashi, N. Nakai, H. Nakamura, M. Okumura and M. Machida, Nuclear magnetic relaxation and superfluid density in Fe-pnictide superconductors: An anisotropic ±s-wave scenario, New J. Phys. 10 103026-1 103026-17 (2008) DOI:10.1088/1367-2630/10/10/103026
  6. Y. Nagai and N. Hayashi, Surface Bound States in n-band Systems with Quasiclassical Approach, Phys. Rev. B 79 224508-1 224508-9 (2009) DOI: 10.1103/PhysRevB.79.224508
  7. S. Nakakura, Y. Nagai and D. Yoshioka, Uniform current in graphene strip with zigzag edges, J. Phys. Soc. Jpn. 78 065003-1 065003-2 (2009) DOI: 10.1143/JPSJ.78.065003
  8. Y. Nagai and Y. Kato, Impurity scattering rate and coherence factor in vortex core of sign-reversing s-wave superconductors, Phys. Rev. B 82 (2010) 174507 DOI: 10.1103/PhysRevB.82.174507
  9. N. Nakai, H. Nakamura, Y. Ota, Y. Nagai, N. Hayashi, and M. Machida, First-principles-based ±pm s-wave modeling for iron-based superconductors:Studies for specific heat and nuclear magnetic relaxation rate, Phys. Rev. B 82 094501-1 094501-5 (2010) DOI: 10.1103/PhysRevB.82.094501
  10. M. Kunimi, Y. Nagai, and Y. Kato, Josephson effects in one-dimensional supersolids, Phys. Rev. B 84 094521-1 094521-9 (2011) DOI: 10.1103/PhysRevB.84.094521
  11. Y. Imai, H. Takahashi, K. Kitagawa, K. Matsubayashi, N. Nakai, Y. Nagai, Y. Uwatoko, M. Machida, A. Maeda, Microwave Surface Impedance Measurements of LiFeAs Single Crystals, J. Phys. Soc. Jpn. 80 013704-1 013704-4 (2011) DOI: 10.1143/JPSJ.80.013704 Most Cited Articles in 2012 from Vol. 80(2011)
  12. Y. Nagai, H. Nakamura, and M. Machida, Superconducting Gap Function in an Organic Superconductor (TMTSF)2ClO4 with Anion Ordering; First-principles Calculations and Quasi-classical Analyses for Angle-resolved Heat Capacity, Phys. Rev. B 83 104523-1 104523-8 (2011) DOI: 10.1103/PhysRevB.83.104523
  13. Y. Nagai, and K. Kuroki, Determination of the pairing state in iron-based superconductors through neutron scattering, Phys. Rev. B 83 220516-1 220516-4(R) (2011) DOI: 10.1103/PhysRevB.83.220516
  14. M. Ishikado, Y. Nagai, K. Kodama, R. Kajimoto, M. Nakamura, Y. Inamura, S. Wakimoto, H. Nakamura, M. Machida, K. Suzuki, H. Usui, K. Kuroki, A. Iyo, H. Eisaki, M. Arai, S. Shamoto, s±-like spin resonance in the iron-based nodal superconductor BaFe2(As0.65P0.35)2 observed using inelastic neutron scattering, Phys. Rev. B 84 144517-1 144517-5 (2011) DOI: 10.1103/PhysRevB.84.144517
  15. Y. Nagai, N. Nakai, and M. Machida, Direct Numerical Demonstration of Sign-preserving Quasiparticle Interference via Impurity inside Vortex Core in Unconventional Superconductors, Phys. Rev. B 85 092505-1 092595-4 (2012) DOI: 10.1103/PhysRevB.85.092505
  16. Y. Nagai, Y. Ota, and M. Machida, Efficient Numerical Self-consistent Mean-field Approach for Fermionic Many-body Systems by Polynomial Expansion on Spectral Density, J. Phys. Soc. Jpn. 81 024710-1 024710-6 (2012) DOI: 10.1143/JPSJ.81.024710
  17. Y. Nagai, and K. Kuroki, Q-scan-analysis of the neutron scattering in iron-based superconductors, Phys. Rev. B 85 134521-1,134521-7 (2012) DOI: 10.1103/PhysRevB.85.134521
  18. Y. Nagai, K. Tanaka, and N. Hayashi, Quasiclassical numerical method for mesoscopic superconductors: bound states in a circular d-wave island with a single vortex, Phys. Rev. B 86, 094526-1, 094526-9 (2012) DOI: 10.1103/PhysRevB.86.094526
  19. Y. Nagai, H. Nakamura, and M. Machida, Rotational Isotropy Breaking as Proof for Spin-polarized Cooper Pair in Topological Superconductor CuxBi2Se3, Phys. Rev. B 86 094507-1, 094507-5 (2012) DOI:09450710.1103/PhysRevB.86.094507
  20. Y. Nagai, Y. Shinohara, Y. Futamura, Y. Ota, and T. Sakurai, Numerical construction of a low-energy effective Hamiltonian in a self-consistent Bogoliubov-de Gennes approach of superconductivity, J. Phys. Soc. Jpn. 82 094701-1,094701-10 (2013) DOI: 10.7566/JPSJ.82.094701
  21. Y. Higashi, Y. Nagai, M. Machida, and N. Hayashi, Field-angle resolved flux-flow resistivity as a phase-sensitive probe of unconventional Cooper pairing, Phys. Rev. B 88 224511-1 224511-6 (2013) DOI: 10.1103/PhysRevB.88.224511
  22. Y. Nagai, H. Nakamura, and M. Machida, * Spin-polarized Majorana Bound States around a Vortex in Topological Superconductors *, J. Phys. Soc. Jpn. 83, 064703-1,064703-7 (2014). DOI: 10.7566/JPSJ.83.064703 'Papers of Editors' Choice'
  23. Y. Nagai, H. Nakamura, and M. Machida, Quasiclassical Treatment and Odd-parity/Triplet Correspondence in Topological Superconductors, J. Phys. Soc. Jpn. 83 053705-1,053705-4 (2014) DOI: 10.7566/JPSJ.83.053705
  24. Y. Nagai, Field-angle-dependent Low-energy Excitations around a Vortex in the Superconducting Topological Insulator CuxBi2Se3, J. Phys. Soc. Jpn. 83 063705-1,063705-4 (2014),DOI: 10.7566/JPSJ.83.063705
  25. Y. Nagai, Y. Ota, and M. Machida, Nonmagnetic impurity effects in a three-dimensional topological superconductor: From p- to s-wave behaviors, Phys. Rev. B 89, 214506-1,214506-6 (2014) DOI: 10.1103/PhysRevB.89.214506
  26. Y. Nagai, Y. Ota, and M. Machida, Impurity effects in a two-dimensional topological superconductor: A link of Tc-robustness with a topological number, J. Phys. Soc. Jpn. 83 094722-1, 094722-5 DOI: 10.7566/JPSJ.83.094722
  27. S. Yoshizawa, H. Kim, T. Kawakami, Y. Nagai, T. Nakayama, X. Hu, Y. Hasegawa, and T. Uchihashi, Imaging Josephson vortices on the surface superconductor Si(111)-(√7 x√3)-In using a scanning tunneling microscope, Phys. Rev. Lett. 113, 247004-1,247004-5, DOI: 10.1103/PhysRevLett.113.247004‘Editors' Suggestion’ ’Featured in Physics’
  28. Y. Nagai, H. Nakamura, and M. Machida, Surface states around a vortex in topological superconductors: Intersection of a surface and a vortex, J. Phys. Soc. Jpn. 84, 033703-1,033703-4 (2015). DOI: 10.7566/JPSJ.84.033703
  29. Y. Nagai, Y. Ota, and M. Machida, Topological s-wave pairing superconductivity with spatial inhomogeneity: Mid-gap-state appearance and robustness of superconductivity, J. Phys. Soc. Jpn. 84, 034711-1,034711-8 (2015). DOI:10.7566/JPSJ.84.034711
  30. Y. Nagai,Robust superconductivity with nodes in the superconducting topological insulator CuxBi2Se3: Zeeman orbital field and non-magnetic impurities, Phys. Rev. B 91, 060502(R)-1,060502(R)-5 (2015). DOI: 10.1103/PhysRevB.91.060502
  31. A. Shitade and Y. Nagai, Orbital angular momentum in a nonchiral topological superconductor, Phys. Rev. B 92, 024502-1,024502-5 (2015). DOI: 10.1103/PhysRevB.92.024502-7
  32. Y. Nagai, H. Nakamura, M. Machida, and K. Kuroki, First-principle study of antimony doping effects on the iron-based superconductor CaFe(SbxAs1-x)2, J. Phys. Soc. Jpn. 84, 093702-1,093702-4 (2015) DOI:10.7566/JPSJ.84.093702
  33. Y. Nagai, Y. Ota, and M. Machida, Inverse coherence effects in nuclear magnetic relaxation rates as a sign of topological superconductivity, Phys. Rev. B 92, 180502(R) (2015), 10.1103/PhysRevB.92.180502
  34. Y. Higashi, Y. Nagai, T. Yoshida, Y. Masaki, and Y. Yanase, Robust zero-energy bound states around a pair-density-wave vortex core in locally noncentrosymmetric superconductors, Phys. Rev. B 93, 104529 (2016),10.1103/PhysRevB.93.104529
  35. A. Shitade and Y. Nagai, Orbital angular momentum in a topological superconductor with Chern number higher than 1, Phys. Rev. B 93, 174517 (2016), DOI:10.1103/PhysRevB.93.174517
  36. Y. Nagai and H. Nakamura, Multi-band Eilenberger theory of superconductivity: Systematic low-energy projection, to be published in J. Phys. Soc. Jpn.
  37. Y. Nagai, S. Hoshino, and Y. Ota, Critical temperature enhancement of topological superconductors: A dynamical mean-field study, Phys. Rev. B 93, 220505(R) (2016), DOI: 10.1103/PhysRevB.93.220505
  38. Y. Nagai, and Y. Ota, Nuclear magnetic relaxation rates of unconventional superconductivity in doped topological insulators, Phys. Rev. B 94, 134516 (2016), DOI: 10.1103/PhysRevB.94.134516
  39. Evan D. B. Smith, K. Tanaka, and Y. Nagai, Manifestation of chirality in the vortex lattice in a two-dimensional topological superconductor, Phys. Rev. B 94, 064515 (2016), DOI: 10.1103/PhysRevB.94.064515
  40. S. Yonezawa, K. Tajiri, S. Nakata, Y. Nagai, Z. Wang, K. Segawa, Y. Ando, and Y. Maeno, Thermodynamic evidence for nematic superconductivity in CuxBi2Se3, Nature Physics 13, 123 (2017), DOI: 10.1038/nphys3907
  41. Y. Nagai, Yasushi Shinohara, Yasunori Futamura, and Tetsuya Sakurai, Reduced-Shifted Conjugate-Gradient Method for a Green's Function: Efficient Numerical Approach in a Nano-structured Superconductor, J. Phys. Soc. Jpn. 86, 014708 (2017), 10.7566/JPSJ.86.014708
  42. H. Kim, S.-Z. Lin, M. J. Graf, Y. Miyata, Y. Nagai, T. Kato, and Y. Hasegawa, Electrical Conductivity through a Single Atomic Step Measured with the Proximity-Induced Superconducting Pair Correlation, Phys. Rev. Lett 117, 116802 (2016), DOI:10.1103/PhysRevLett.117.116802
  43. Y. Nagai, Y. Ota, and K. Tanaka, Time-reversal symmetry breaking and gapped surface states due to spontaneous emergence of new order in d-wave nanoislands, Phys. Rev. B 96, 060503(R) (2017), DOI: 10.1103/PhysRevB.96.060503
  44. S. L. Goertzen, K. Tanaka, and Y. Nagai, Self-consistent study of Abelian and non-Abelian order in a two-dimensional topological superconductor, Phys. Rev. B 95, 064509 (2017), DOI: 10.1103/PhysRevB.95.064509
  45. Y. Nagai, H. Shen, Y. Qi, J. Liu, and L. Fu, Self-Learning Monte Carlo Method: Continuous-Time Algorithm, Phys. Rev. B 96, 161102(R) (2017), DOI: 10.1103/PhysRevB.96.161102
  46. K. Iida, M. Ishikado, Y. Nagai, H. Yoshida, A. D. Christianson, N. Murai, K. Kawashima, Y. Yoshida, H. Eisaki, and A. Iyo, Spin Resonance in the New-Structure-Type Iron-Based Superconductor CaKFe4As4, J. Phys. Soc. Jpn. 86 0937031-0937034 (2017), DOI: 10.7566/JPSJ.86.093703
  47. Y. Nagai and H. Shinaoka, Smooth self-energy in the exact-diagonalization-based dynamical mean-field theory: Intermediate-representation filtering approach, J. Phys. Soc. Jpn. 88, 064004 (2019), DOI: 10.7566/JPSJ.88.064004
  48. Y. Nagai and Y. Kato, Quasiparticle Bound States around Fractional Vortices in s-wave Superconductor, J. Phys. Soc. Jpn. 88, 054707 (2019), DOI:10.7566/JPSJ.88.054707
  49. K. Iida, Y. Nagai, S. Ishida, M. Ishikado, N. Murai, A. D. Christianson, H. Yoshida, Y. Inamura, H. Nakamura, A. Nakao, K. Munakata, D. Kagerbauer, M. Eisterer, K. Kawashima, Y. Yoshida, H. Eisaki, and A. Iyo, Coexisting spin resonance and long-range magnetic order of Eu in EuRbFe4As4, Phys. Rev. B 100, 014506 (2019), DOI: 10.1103/PhysRevB.100.014506
  50. M. Kheirkhah, Y. Nagai, C. Chen, F. Marsiglio, * Majorana corner flat bands in two-dimensional second-order topological superconductors *, Phys. Rev. B 101, 104502 (2020), DOI: 10.1103/PhysRevB.101.104502
  51. T. Matsushita, Y. Nagai, S. Fujimoto, Disorder-induced exceptional and hybrid rings in Weyl/Dirac semimetals, Phys. Rev. B 100, 245205 (2019), DOI:10.1103/PhysRevB.100.245205
  52. Yuki Nagai, N-independent Localized Krylov Bogoliubov-de Gennes Method: Ultra-fast Numerical Approach to Large-scale Inhomogeneous Superconductors, J. Phys. Soc. Jpn. 89, 074703 (2020)
  53. Y. Nagai, M. Okumura, and A. Tanaka, Self-learning Monte Carlo method with Behler-Parrinello neural networks, Phys. Rev. B 101, 115111 (2020), DOI:10.1103/PhysRevB.101.115111
  54. Etsuko Itou and Yuki Nagai, Sparse modeling approach to obtaining the shear viscosity from smeared correlation functions, Journal of High Energy Physics volume 2020, 7 (2020)
  55. Majid Kheirkhah, Zhongbo Yan, Yuki Nagai, Frank Marsiglio, First and second-order topological superconductivity and temperature-driven topological phase transitions in the extended Hubbard model with spin-orbit coupling, Phys. Rev. Lett. 125, 017001 (2020)
  56. Yuki Nagai, Yang Qi, Hiroki Isobe, Vladyslav Kozii, and Liang Fu, DMFT Reveals the Non-Hermitian Topology and Fermi Arcs in Heavy-Fermion Systems, Phys. Rev. Lett. 125, 227204-1, 227204-7 (2020)
  57. Yuki Nagai, Masahiko Okumura, Keita Kobayashi, and Motoyuki Shiga, Self-learning hybrid Monte Carlo: A first-principles approach, Phys. Rev. B 102, 041124(R)-1,041124(R)-6 (2020)
  58. Hiroshi Shinaoka and Yuki Nagai, Sparse modeling of large-scale quantum impurity models with low symmetries, Physical Review B 103, 045120-1, 045120-8 (2021)
  59. Hidehiko Kohshiro, and Yuki Nagai, Effective Ruderman–Kittel–Kasuya–Yosida-like Interaction in Diluted Double-exchange Model: Self-learning Monte Carlo Approach, J. Phys. Soc. Jpn. 90, 034711-1, 034711-8 (2021)
  60. Taiki Matsushita, Yuki Nagai, and Satoshi Fujimoto, Spectrum Collapse of Disordered Dirac Landau Levels as Topological Non-Hermitian Physics, J. Phys. Soc. Jpn. 90, 074703-1, 074703-9 (2021)
  61. Keita Kobayashi, Yuki Nagai, Mitsuhiro Itakura, and Motoyuki Shiga, Self-learning hybrid Monte Carlo method for isothermal-isobaric ensemble: Application to liquid silica, The Journal of Chemical Physics 155, 034106-1, 034106-9 (2021)
  62. Howon Kim, Yuki Nagai, Levente Rózsa, Dominik Schreyer, and Roland Wiesendanger, Anisotropic non-split zero-energy vortex bound states in a conventional superconductor, Applied Physics Reviews 8, 031417-1, 031417-8 (2021)
  63. Yuki Nagai, Intrinsic vortex pinning in superconducting quasicrystals, Phys. Rev B 106, 064506-1-10 (2022)
  64. Markus Wallerberger, Samuel Badr, Shintaro Hoshino, Sebastian Huber, Fumiya Kakizawa, Takashi Koretsune, Yuki Nagai, Kosuke Nogaki, Takuya Nomoto, Hitoshi Mori, Junya Otsuki, Soshun Ozaki, Thomas Plaikner, Rihito Sakurai, Constanze Vogel, Niklas Witt, Kazuyoshi Yoshimi, Hiroshi Shinaoka, sparse-ir: Optimal compression and sparse sampling of many-body propagators, SoftwareX 21 101266 1-7 (2023)
  65. T. Machida, Yuki Nagai, and T. Hanaguri, Zeeman effects on Yu-Shiba-Rusinov states, Phys. Rev. Research 4, 033182 1-12 (2022)
  66. Yuki Nagai, Akinori Tanaka, and Akio Tomiya, Self-learning Monte Carlo for non-Abelian gauge theory with dynamical fermions, Phys. Rev. D 107, 054501 1-16 (2023)
  67. Yuki Nagai, and Hiroshi Shinaoka, Sparse Modeling Approach for Quasiclassical Theory of Superconductivity, Journal of the Physical Society of Japan 92, 034703 1-8 (2023)

国際学会プロシーディングス(古い年次順で記載)24本(第一著者9本)

  1. Y. Nagai, H. Akera and H. Suzuura, Spatial Variations of the Hall Potential and the Electron Temperature in Quantum Hall Systems with a Filling Factor Step, The 28th International Conference on the Physics of Semiconductors, Vienna, Austria, 2006, AIP Conference Proceedings 893 665 (2007) DOI:10.1063/1.2730066
  2. Y. Nagai, N. Hayashi, Y. Kato, K. Yamauchi and H. Harima, Field angle dependence of the zero-energy density of states in unconventional superconductors: analysis of the borocarbide superconductor YNi$2$B$2$C, The 25th international conference on Low Temperature Physics (LT24), Amsterdam, The Netherlands, 2008, J. Phys.: Conf. Ser. 150 (2009) 052177 DOI:10.1088/1742-6596/150/5/052177
  3. N. Hayashi, Y. Nagai, and Y. Higashi, Analysis of field-angle dependent specific heat in unconventional superconductors: a comparison between Doppler-shift method and Kramer-Pesch approximation, The 9th International Conference on Materials and Mechanisms of Superconductivity (M2S), Tokyo, 2009, Physica C 470, (2010) S865 DOI:10.1016/j.physc.2009.10.045
  4. Y. Nagai, N. Hayashi, and M. Machida, Surface-angle dependence of the tunneling spectroscopy in iron-based superconductors: sign-reversing s-wave scenarios, The 9th International Conference on Materials and Mechanisms of Superconductivity (M2S), Tokyo, 2009, Physica C 470 (2010) S504 DOI:10.1016/j.physc.2009.10.043
  5. M. Machida, Y. Nagai, Y. Ota, N. Nakai, H. Nakamura, and N. Hayashi, Phenomenological theory for ±s-wave superconducting states of iron-based superconductors, The 9th International Conference on Materials and Mechanisms of Superconductivity (M2S), Tokyo, 2009, Physica C 470 (2010) S372 DOI:10.1016/j.physc.2009.10.087
  6. N. Nakai, H. Nakamura, Y. Ota, Y. Nagai, N. Hayashi, and M. Machida, Small jump of specific heat and small gap in iron pnictide superconductors, The 9th International Conference on Materials and Mechanisms of Superconductivity (M2S), Tokyo, 2009, Physica C 470 (2010) S368 DOI: 10.1016/j.physc.2010.01.055
  7. N. Nakai, Y. Nagai, and M. Machida, Low-lying excitations induced by non-magnetic impurities in d-wave superconductors, The 24th International Symposium on Superconductivity (ISS2010), Tsukuba, 2010, Physica C 471 (2011) 743 DOI:10.1016/j.physc.2011.05.042
  8. Y. Higashi, Y. Nagai, M. Machida and N. Hayashi, Field-angle dependence of the quasiparticle scattering inside a vortex core in unconventional superconductors, The 24th International Symposium on Superconductivity (ISS2010), Tsukuba, 2010, Physica C 471 (2011) 828 DOI: 10.1016/j.physc.2011.05.066
  9. Y. Nagai, H. Nakamura, K. Suzuki, H. Usui, K. Kuroki, and M. Machida, Theoretical analysis for inelastic neutron scattering on BaFe2(As1−xPx)2 by the realistic three-dimensional 10-orbital tight-binding model, International Workshop on Neutron Applications on Strongly Correlated Electron Systems 2011, Ibaraki, 2011, J. Phys. Soc. Jpn. 80 (2011) SB021 DOI:10.1143/JPSJS.80SB.SB021
  10. Y. Nagai, Y. Ota, and M. Machida, Spectral-density polynomial expansion for two-particle Green's function in BdG framework, The 24th International Symposium on Superconductivity (ISS2011), Tokyo, 2011, Physics Procedia 27 (2012) 72 DOI:10.1016/j.phpro.2012.03.413
  11. Y. Higashi, Y. Nagai, M. Machida, and N. Hayashi, Phase-Sensitive Flux-Flow resistivity in Unconventional Superconductors, The 26th International Conference on Low Temperature Physics (LT26), Beijing, China, 2011, J. Phys.: Conf. Ser. 400, (2012) 022025 DOI:10.1088/1742-6596/400/2/022025
  12. Y. Higashi, Y. Nagai, M. Machida, and N. Hayashi, Effect of uniaxially anisotropic Fermi surface on the quasiparticle scattering inside a vortex core in unconventional superconductors, the 24th International Symposium on Superconductivity (ISS2011), Tokyo, 2011 Physica C 484 (2013) 97 DOI: 10.1016/j.physc.2012.03.038
  13. Y. Nagai, H. Nakamura, and M. Machida, Andreev Bound-states of vortices and surfaces in topological superconductors, International Conference Dubna-Nano, Dubna, Russia, 2012, J. Phys.: Conf. Ser. 393 (2012) 012017 DOI: 10.1088/1742-6596/393/1/012017
  14. Y. Higashi, Y. Nagai, M. Machida, and N. Hayashi, Effect of Anisotropic Fermi Surface on the Flux-flow Resistivity under Rotating Magnetic Field, the 25th International Symposium on Superconductivity (ISS2012), Tokyo, 2012, Physics Procedia 45 (2013) 137, DOI:10.1016/j.phpro.2013.04.071
  15. J. W. Sadowski, K. Tanaka, and Y. Nagai, Effects of band structure and electron–phonon coupling on charge density waves, Theory Canada 7, Lethbridge, Canada, 2012, Canadian Journal of Physics, 91 (2013) 487 DOI: 10.1139/cjp-2012-0440
  16. Y. Nagai, H. Nakamura, M. Machida, Surface and vortex bound states in topological superconductors, The 25th International Symposium on Superconductivity (ISS2012), Tokyo, 2012, Physica C 494 (2013) 17 DOI: 10.1016/j.physc.2013.04.018
  17. T. Yamane, Y. Nagai, K. Tanaka, and N. Hayashi, Impurity scattering effect on the zero-energy peak of the local density of states in a multi-quantum vortex core, The 25th International Symposium on Superconductivity (ISS2012), Tokyo, 2012, Physica C 494 (2013) 128 Physica C DOI:10.1016/j.physc.2013.04.046
  18. Y. Higashi, Y. Nagai and N. Hayashi, Impurity Effect on the Local Density of States around a Vortex in Noncentrosymmetric Superconductors, Proc. Int. Conf. Strongly Correlated Electron Systems (SCES2013), JPS Conf. Proc. 3, 015003 (2014) , DOI: 10.7566/JPSCP.3.015003
  19. Y. Nagai, H. Nakamura, and M. Machida, Inhomogeneity Effects in Topological Superconductors, Proc. Int. Conf. Strongly Correlated Electron Systems (SCES2013), JPS Conf. Proc. 3, 015013 (2014) , DOI: 10.7566/JPSCP.3.015013
  20. Y. Nagai, Y. Ota and M. Machida, Robustness against non-magnetic impurities in topological superconductors, J. Phys.: Conf. Ser. 568, 022030 (2014), DOI:10.1088/1742-6596/568/2/022030
  21. Y. Higashi, Y. Nagai, T. Yoshida and Y. Yanase, Vortex Core Structure in Multilayered Rashba Superconductors, J. Phys.: Conf. Ser. 568, 022018 (2014), DOI:10.1088/1742-6596/568/2/022018
  22. T. Kawakami, Y. Nagai, S. Yoshizawa, H. Kim, Y. Hasegawa, T. Nakayama, T. Uchihashi and X. Hu, Excitation spectrum of Josephson vortices on surface superconductor, J. Phys.: Conf. Ser. 568, 022022 (2014), DOI:10.1088/1742-6596/568/2/022022
  23. Y. Ota, Y. Nagai, and M. Machida, Theory of low-energy behaviors in topological s-wave pairing superconductors, Physica C 518, 5-9 (2015),doi:10.1016/j.physc.2015.08.002
  24. Y. Higashi, Y. Nagai, T. Yoshida, M. Kato, and Y. Yanase, Excitation spectra and wave functions of quasiparticle bound states in bilayer Rashba superconductors, Physica C 518 1-4 (2015),doi:10.1016/j.physc.2015.03.004

国際・国内会議での招待講演発表

  1. Y. Nagai, N. Hayashi, N. Nakai, H. Nakamura, M. Okumura and M. Machida, Anisotropic \pm s-wave Scenario as a Possible Superconductivity in Fe-based High-Tc Superconductor, International Symposium on Topological Science and Technology for Young Researchers 2009 (Sapporo, Japan, 2009)
  2. Y. Nagai and Y. Kato, Sign-reversing s-wave superconductors: Analysis of the Fe-based superconductors, 12th International Workshop on Vortex Matter in Superconductors 2009 (Lake Yamanaka, Japan, 2009)
  3. Y. Nagai and M. Machida, Large-scale self-consistent BdG calculation in vortex lattice system, The First International Workshop on Superconducting Vortex Matter (Zhejiang Normal University, Jinhua, China, 2011)
  4. Y. Nagai, N. Nakai, and M. Machida, Direct Large-scale Numerical Demonstration of Quasiparticle Interference in Magnetic Fields: Orthonormal Polynomial Approach, 13th International Workshop on Vortex Matter in Superconductors 2011 (Chicago, USA, 2011)
  5. Y. Nagai, K. Tanaka, and N. Hayashi, Numerical method for mesoscopic superconductors in the quasiclassical theory, International workshop on Pathbreaking Phase Sciences in Superconductivity 2012 (Osaka Museum of History, Osaka, Japan, 2012)
  6. Y. Nagai, H. Nakamura, and M. Machida, Andreev Bound-states of vortices and surfaces in topological superconductors, International Conference Dubna-Nano2012, (Dubna, Russia, 2012)
  7. Y. Nagai, H. Nakamura, and M. Machida, Effective theory in Bulk topological superconductors, 14th International Workshop on Vortex Matter in Superconductors 2013 (Nanjing, China, 2013)
  8. Y. Nagai, H. Nakamura, and M. Machida, Spin-polarized majorana quasiparticle bound states in topological superconductors, The 25th International Symposium on Superconductivity (ISS2014) (Tokyo, 2014)
  9. Y. Nagai, Quasiparticle excitations in a nodal topological superconductor: Application to superconducting topological insulator CuxBi2Se3, 15th International Workshop on Vortex Matter in Superconductors 2015 (El Escorial, Spain, 2015)
  10. Y. Nagai, 準古典Eilenberger 理論による非従来型超伝導体の理論的研究, 2015年日本物理学会年次大会 早稲田大 22pAA-3 (2015)
  11. Y. Nagai, Y. Ota, and K. Tanaka, Time-reversal symmetry breaking phase, gapped surface states, and vortex-antivortex pairs in d-wave nanoislands, 16th International Workshop on Vortex Matter in Superconductors, (Natal, Brazil, 2017)
  12. Y. Nagai, Y. Ota, K. Tanaka, Spontaneous time-reversal breaking and topologically protected gapless states in unconventional nano superconductors, TMS-EPiQS 2nd Alliance Workshop; Topological Magnets and Topological Superconductors, (Kyoto, 2018)
  13. Y. Nagai, Y. Qi, H. Isobe, V. Kozii, and L. Fu, Bulk Topological Fermi arcs in heavy fermion systems, 4th Conference on Condensed Matter Physics, (Shanghai, China, 2018)
  14. Y. Nagai, 自己学習モンテカルロ法, 深層学習と物理2018, (Toyonaka, 2018)
  15. Y. Nagai, 自己学習モンテカルロ法;機械学習を用いたモンテカルロ法の高速化, 第7回材料系ワークショップ, (Tokyo, 2019)
  16. Y. Nagai, Self-learning Monte Carlo method; Speedup of the Markov chain Monte Carlo with machine learning, Quantum Engineering meets Harmonic Analysis, (Saskatoon, Canada, 2019)
  17. Y. Nagai, Non-hermitian physics in strongly correlated electron systems, EPiQS-TMS 3rd Alliance Workshop on Topological Materials Science (UCSB, USA, 2019)
  18. Y. Nagai, Non-Hermitian effective Hamiltonian for low-energy quasiparticles, Topological Materials Science 2019 (TopoMat2019) (Kyoto, Japan, 2019)

解説

  1. 為ヶ井 強、足立 匡、永井 佑紀, 第10回M2S国際会議報告、 固体物理(アグネ技術センター)、47(12) (2012) 779 2)
  2. 永井 佑紀, 自己学習モンテカルロ法 : 機械学習を用いたマルコフ連鎖モンテカルロ法の加速 (特集 機械学習と分子シミュレーション)、アンサンブル : 分子シミュレーション研究会会誌 (査読あり)

学会発表、国内会議

学会発表、国内会議のリストはこちら


博士論文

永井佑紀
鉄系超伝導体の超伝導対称性に関する理論的研究
博士論文 (東京大学)
[PDF][10.9MB]
学位論文要旨[LINK]


修士論文

永井佑紀
超伝導量子渦糸系における局所電子状態密度に関する解析的理論
修士論文 (東京大学)
[PDF][7.06MB]
発表内容スライド[PDF][13.7MB]


卒業論文

Y. Nagai
Electron Temperature Distribution in Quantum Hall Systems with Potential Steps
Graduation Thesis (Hokkaido Univ.)
[PDF]


著書

永井佑紀 (著), 涌井 貞美 (著), 現代用語の基礎知識 (編さん)
理科のおさらい物理 (おとなの楽習 5)
自由国民社
[Amazon]


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大阪府立大学での講義「超伝導シミュレーション研究の最前線」 2014年7月15日
講義発表資料(パスワード保護) (約35MB)

共同研究者のリンク
東陽一さん(大阪府立大学)

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