English / Japanese

Yuki Nagai, Ph. D.

CCSE, Japan Atomic Energy Agency (JAEA)
Position : Scientist

Email : Nagai.Yuki_-at.-mark.-_jaea.go.jp (Replace _-at-mark-_ with @)


MAJOR: Condensed Matter Physics (Theory)
especially, Superconductivity
Researcher ID:

Academic Qualifications

2001-2005 : B. Eng. Department of Applied Physics, Hokkaido University.
Supervisor : Prof. H. Akera.
Subject : "Electron Temperature Distribution in Quantum Hall Systems with Potential Steps"

2005-2007 : M. Sci. Department of Physics, University of Tokyo.
Supervisor : Asso. Prof. Y. Kato.
Subject : "Analytical Theory of the Local Density of States around a Vortex in Superconductors"

2007-2010 : Ph. D. research at Department of Physics, University of Tokyo.
Supervisor : Asso. Prof. Y. Kato.
Subject : "Theoretical study of pairing symmetries in iron-based superconductors"


Awards
Mar. 2015: Young Scientist Award of the Physical Society of Japan


Recent Researches

42. Howon Kim, Shi-Zeng Lin, Matthias J. Graf, Yoshinori Miyata, Yuki Nagai, Takeo Kato, and Yukio Hasegawa
Electrical Conductivity through a Single Atomic Step Measured with the Proximity-Induced Superconducting Pair Correlation
Phys. Rev. Lett 117, 116802 (2016). [link]

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
arXiv:1607.03992

40. Shingo Yonezawa, Kengo Tajiri, Suguru Nakata, Yuki Nagai, Zhiwei Wang, Koji Segawa, Yoichi Ando, and Yoshiteru Maeno
Thermodynamic evidence for nematic superconductivity in CuxBi2Se3
arXiv:1602.08941

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). [link]
arXiv:1605.08934

38. Y. Nagai and Y. Ota
Nuclear magnetic relaxation rates of unconventional superconductivity in doped topological insulators
arXiv:1605.08164

37. Yuki Nagai, Shintaro Hoshino, and Yukihiro Ota
Critical Temperature Enhancement of Topological Superconductors: A Dynamical Mean Field Study
Phys. Rev. B 93, 220505(R) (2016). [link]
arXiv:1602.06087

36. Yoichi Higashi, Yuki Nagai, Tomohiro Yoshida, Yusuke Masaki, and Youichi Yanase
Robust zero-energy bound states around a pair-density-wave vortex core in locally noncentrosymmetric superconductors
Phys. Rev. B 93, 104529 (2016). [link]
arXiv:1602.00425

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). [link]
arXiv:1512.07997

34. Y. Nagai, and H. Nakamura
Multi-band Eilenberger theory of superconductivity: Systematic low-energy projection
J. Phys. Soc. Jpn. 85, 074707 (2016). [link]
arXiv:1507.06039

33. Y. Nagai, H. Nakamura, M. Machida, and K. Kuroki
First-principle study of antimony doping effects on the iron-based superconductor CaFe(Sb$_{x}$As$_{1-x}$)$_{2}$
J. Phys. Soc. Jpn. 84, 093702 (2015). [link]
arXiv:1506.08515

32. 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). [link]
arXiv:1504.08095

31. A. Shitade and Y. Nagai
Orbital angular momentum in a nonchiral topological superconductor
Phys. Rev. B 92, 024502 (2015). [link]
arXiv:1501.06677

30. Y. Nagai, H. Nakamura, M. Machida
Surface states around a vortex in topological superconductors: Intersection of a surface and a vortex
J. Phys. Soc. Jpn. 84, 033703 (2015). [link]
arXiv:1412.5713

29. 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) (2015). [link]
arXiv:1410.4646

28. Y. Nagai, Y. Ota, and M. Machida
Topological s-wave pairing superconductivity with spatial inhomogeneity: Mid-gap-state appearance and Anderson's theorem
J. Phys. Soc. Jpn. 84, 034711 (2015). [link]
arXiv:1407.1125

27. S. Yoshizawa, H. Kim, T. Kawakami, Y. Nagai, T. Nakayama, X. Hu, Y. Hasegawa, and T. Uchihashi
Direct Observation of Josephson Vortices on the Surface Superconductor Si(111)-(root7xroot3)-In by Scanning Tunneling Microscopy
Phys. Rev. Lett. 113, 247004. [link] Featured in Physics and Editors' Suggestion
"Ultrathin Superconductors Take a Step Up"
arXiv:1405.5953

26. Y. Nagai
Field-angle-dependent low-energy excitations around a vortex in the superconducting topological insulator CuxBi2Se3
J. Phys. Soc. Jpn. 83 (2014) 063705. [link]
arXiv:1404.6874

25. Y. Nagai, Y. Ota, and M. Machida
From p- to s-wave behaviors in a three-dimensional topological superconductor with non-magnetic impurities
Phys. Rev. B 89, 214506 (2014) 214506. [link]
arXiv:1404.1662

24. 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 (2014) 094722. [link]
arXiv:1312.3065

23. Y. Nagai, H. Nakamura, M. Machida
Quasiclassical Treatment and Odd-parity/Triplet Correspondence in Topological Superconductors
J. Phys. Soc. Jpn. 83 (2014) 053705. [link]
arXiv:1305.3025

22. Y. Higashi, Y. Nagai, M. Machida, N. Hayashi
Field-angle Resolved Flux-flow Resistivity as a Phase-sensitive Probe of Unconventional Cooper Pairing
Phys. Rev. B 88 (2013) 224511. [link]
arXiv:1304.6509

21. Y. Nagai, Yasushi Shinohara, Yasunori Futamura, Yukihiro Ota, and Tetsuya Sakurai
Numerical construction of a low-energy effective Hamiltonian in a self-consistent Bogoliubov-de Gennes approach of superconductivity
J. Phys. Soc. Jpn. 82 (2013) 094701. [link]
arXiv:1303.3683

20. Y. Nagai, H. Nakamura, and M. Machida
Spin-polarized Majorana Bound States around a Vortex in Topological Superconductors
J. Phys. Soc. Jpn. 83 (2014) 064703. [link] Papers of Editors' Choice
"Hunting Majorana Fermions in Topological Superconductors" in JPSJ News and Comments
arXiv:1211.0125

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 (2012) 094507. [link]
arXiv:1206.0563

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 (2012) 094526. [link]
arXiv:1202.2661

17. Y. Nagai, and K. Kuroki
Q-scan-analysis of the neutron scattering in iron-based superconductors
Phys. Rev. B 85 (2012) 134521. [link]
arXiv:1201.2453

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 (2012) 024710. [link]
arXiv:1105.4939

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 (2012) 092505. [link]
arXiv:1103.5842

14. Y. Nagai, and K. Kuroki
Determination of the pairing state in iron-based superconductors through neutron scattering
Phys. Rev. B 83 (2011) 220516(R). [link]
arXiv:1103.0586

13. 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 (2011) 104523. [link]
arXiv:1101.2277

12. 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 (2011) 144517. [link]
arXiv:1011.3191

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 (2011) 013704. [link]
arXiv:1009.4628

10. M. Kunimi, Y. Nagai , and Y. kato
Josephson effects in one-dimensional supersolids
Phys. Rev. B 84 (2011) 094521. [link]
arXiv:1005.3936

9. N. Nakai, H. Nakamura, Y. Ota, Y. Nagai , N. Hayashi and M. Machida
First-principles-based €pm s-wave modelling for iron-based superconductors:Studies for specific heat and nuclear magnetic relaxation rate
Phys. Rev. B 82 (2010) 094501. [link]
arXiv:0909.1195

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. [link]
arXiv:0908.4451

7. S. Nakakura, Y. Nagai and D. Yoshioka
Uniform current in graphene strip with zigzag edges
J. Phys. Soc. Jpn. 78 (2009) 065003. [link]
arXiv:0903.1483

6. Y. Nagai and N. Hayashi
Surface Bound States in n-band Systems with Quasiclassical Approach
Phys. Rev. B 79 (2009) 224508. [link]
arXiv:0903.1227

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 \pm s-wave scenario
New J. Phys. 10 (2008) 103026. [link]
arXiv:0809.1197

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 (2008) 097001. [link]
arXiv:0802.1579

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, (2007) 214514. [link]
arXiv:0706.1863

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 (2006) 104701.[link]
cond-mat/0605441

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 (2006) 043706 [link]
cond-mat/0602254


Preprints in cond-mat
publicationlist.org


Comments

1. Y. Nagai and K. Kuroki
Comment on arXiv:1105.6233 entitled "Neutron-Inelastic-Scattering Peak by Dissipationless Mechanism in the s++-wave State in Iron-based Superconductors" by S. Onari and H. Kontani
arXiv:1106.2376


Proceedings

25. Y. Ota, Y. Nagai, and M. Machida
Theory of low-energy behaviors in topological s-wave pairing superconductors
Physica C. 518 5 (2015)
[link]

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 (2015)
[link]

23. 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)
[link]

22. Y. Higashi, Y. Nagai, T. Yoshida, and Y. Yanase
Vortex Core Structure in Multilayered Rashba Superconductors
J. Phys.: Conf. Ser. 568 022018 (2014)
[link]

21. Y. Nagai, Y. Ota, and M. Machida,
Robustness against non-magnetic impurities in topological superconductors
J. Phys.: Conf. Ser. 568 022030 (2014)
[link]

20. Y. Nagai, H. Nakamura, and M. Machida,
Inhomogeneity Effects in Topological Superconductors
JPS Conf. Proc. 3, 015013 (2014)
[link]

19. T. Higashi, Y. Nagai, and N. Hayashi,
Impurity Effect on the Local Density of States around a Vortex in Noncentrosymmetric Superconductors
JPS Conf. Proc. 3, 015003 (2014)
[link]

18. 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
Physica C 494 (2013), 128
[link]

17. Y. Nagai, H. Nakamura, and M. Machida
Surface and vortex bound states in topological superconductors
Physica C 494 (2013), 17
[link]

16. J. W. Sadowski, K. Tanaka, and Y. Nagai
Effects of band structure and electron-phonon coupling on charge density waves
Canadian Journal of Physics, 91 (2013) 487
[link]

15. Y. Higashi, Y. Nagai, M. Machida, and N. Hayashi
Effect of Anisotropic Fermi Surface on the Flux-flow Resistivity under Rotating Magnetic Field
Physics Procedia 45 (2013) 137
[link]

14. Y. Nagai, H. Nakamura, and M. Machida
Andreev Bound-states of vortices and surfaces in topological superconductors
J. Phys.: Conf. Ser. 393 (2012) 012017
[link]

13. 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
Physica C 484 (2013) 97
[link]

12. Y. Higashi, Y. Nagai, M. Machida, and N. Hayashi
Phase-Sensitive Flux-Flow resistivity in Unconventional Superconductors
J. Phys.: Conf. Ser. 400, (2012) 022025
[link]

11. Y. Nagai, Y. Ota, and M. Machida
Spectral-density polynomial expansion for two-particle Green's function in BdG framework
Physics Procedia 27 (2012) 72
[link]

10. 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
J. Phys. Soc. Jpn. 80 (2011) SB021
[link]

9. Y. Higashi, Y. Nagai, M. Machida and N. Hayashi
Field-angle dependence of the quasiparticle scattering inside a vortex core in unconventional superconductors
Physica C 471 (2011) 828
[link]

8. N. Nakai, Y. Nagai, and M. Machida
Low-lying excitations induced by non-magnetic impurities in d-wave superconductors
Physica C 471 (2011) 743
[link]

7. 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
Physica C 470 (2010) S368
[link]

6. Y. Nagai, K. Kuroki, M. Machida, H. Aoki
Impurity effect in multi-orbital, sign-reversing s-wave superconductors
arXiv:1012.5565

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
Physica C 470 (2010) S372
[link]

4. Y. Nagai, N. Hayashi, and M. Machida
Surface-angle dependence of the tunneling spectroscopy in iron-based superconductors: sign-reversing s-wave scenarios
Physica C 470 (2010) S504
[link] arXiv:0910.4040

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
Physica C 470, (2010) S865
[link] arXiv:0910.3993

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
Journal of Physics: Conference Series 150 (2009) 052177 [link]
arXiv:0901.2758

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 Proceedings of the 28th International Conference on the Physics of Semiconductors. 2006, AIP Conference Proceedings 893 665 (2007). [link]


International Conference

19. Y. Nagai, H. Nakamura, and M. Machida
Andreev Bound-states in topological superconductors
M2S 2012 Materials and Mechanisms of Superconductivity , (Washington, D. C., USA, July 29– August 3 2012)
Poster

18. Y. Nagai, H. Nakamura, and M. Machida
Andreev Bound-states of vortices and surfaces in topological superconductors
International Conference Dubna-Nano2012, (Dubna, Russia, July 9–14 2012)
Oral (Invited)

17. J. W. Sadowski, K. Tanaka, Y. Nagai
Mechanism of charge density waves in an attractive Hubbard model
The Canadian Association of Physicists Annual Congress, University of Calgary, June 2012
Poster (K. Tanaka)

16. J. W. Sadowski, K. Tanaka, Y. Nagai
Effects of band structure and electron-phonon coupling on charge density waves
Theory Canada 7, University of Lethbridge, June 2012
Oral (The speaker is K. Tanaka)

15. Y. Nagai, K. Tanaka, and N. Hayashi
Numerical method of the quasiclassical theory for mesoscopic superconductors
Americal Physical Society March Meeting 2012 (Boston, USA, February 27–March 2 2012)
Poster

14. 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, January 13-15)
Oral (Invited)

13. Y. Nagai, Y. Ota, and M. Machida
Spectral-density polynomial expansion for two-particle Green's function in BdG framework
24th International Symposium on Superconductivity 2011 (Funabari, Tokyo, Japan, October 26-28)
Poster

12. Y. Nagai, N. Nakai, and M. Machida
Direct Large-scale Numerical Demonstration of Quasiparticle Interference in Magnetic Fields: Orthonormal Polynomial Approach
12th International Workshop on Vortex Matter in Superconductors 2011 (Chicago, USA, July 31 - August 5)
Oral (Invited)

11. 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, May 27-31)
Oral (Invited)

10. Y. Nagai, H. Nakamura, K. Suzuki, H. Usui, K. Kuroki, and M. Machida
Theoretical study on inelastic neutron scattering on BaFe2(As1-xPx)2 by the realistic three-dimensional 10-orbital tight-binding model
International Workshop on Novel Superconductors and Super Materials 2011 (National Museum of Emerging Science and Innovation, Tokyo, Japan, March 6-8)
Poster

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 Quantum Beam Research Center (IQBRC), Tokai, Ibaraki, Japan, February 23-25)
Poster

8. Y. Nagai, K. Kuroki, M. Machida, and H. Aoki
Impurity effect in multi-orbital, sign-reversing s-wave superconductors
23rd International Symposium on Superconductivity 2010 (Tsukuba, Ibaraki, Japan, November 1-3)
Oral

7. 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, August 12-16)
Oral (Invited)

6. 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 2009 (Tokyo, Japan, August 7-12)
Poster

5. *D. Yoshioka, S. Nakakura and Y. Nagai
Unexpected current distribution in graphene ribbon with zigzag edges
The 18th International Conference on Electronic Properties of Two-Dimensional Systems (EP2DS-18) (Kobe, Japan, July 19-24 2009)
Tu-eP971 Poster (The speaker is D. Yoshioka)

4. 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, March 3-5)
Oral (Invited)

3. Y. Nagai, Y. Kato and N. Hayashi
Field angle dependence of the zero-energy density of states in unconventional superconductors: analysis of the borocarbide superconductor YNi2B2C
25th international conference on Low Temperature Physics (Amsterdam, The Netherlands, August 6-13 2008)
Poster

2. Y. Nagai, Y. Kato and N. Hayashi
Field Angle Dependence of the Zero Energy Density of States in Unconventional Superconductors
YKIS2007 Interaction and Nanostructural Effects in Low-Dimensional Systems (Kyoto, Japan, November 5-30 2007)
Poster

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
28th International Conference on the Physics of Semiconductors (Vienna, Austria, July 24-28 2006)
TuA3n.24 Poster (The speaker is H. Akera)




Doctor Thesis

Y. Nagai
Theoretical study of pairing symmetries in iron-based superconductors (in Japanese)
Doctor Thesis (Univ. of Tokyo)
[PDF]


Master Thesis

Y. Nagai
Analytical Theory of the Local Density of States around a Vortex in Superconductors (in Japanese)
Master Thesis (Univ. of Tokyo)
[PDF]


Graduation Thesis

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


Collaborator's link
Yoich Higashi (Osaka Prefecture University)

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