Kenjiro Okawa

• 2022.10 - 　　　Seniour Research Scientist at Applied Erectrical Standards Group RIPM, NMIJ, AIST
• 2020.11 - 　　　Member at Thermoelectrics and Thermal Management Team, GZR, AIST
• 2017.04 - 2022.09　Research Scientist at Applied Erectrical Standards Group RIPM, NMIJ, AIST
• 2015.04 - 2017.03　Research Fellowship for Young Scientists DC2, Japan Society for the Promotion of Science (JSPS)

・　Thermoelectric effects：Development of Thermoelectric Measurements (2017 - )

・　Condensed matter physics: Exploration of Topological Materials (2012 - )

1. "Accurate determination of thermoelectric figure of merit using ac Harman method with a four-probe configuration"
   K. Okawa, Y. Amagai, N. Sakamoto, and N.-H. Kaneko
   Measurement 232, 114626 (2024).
   
2. "Precision ratiometric technique for measuring the Peltier coefficient"
   Y. Amagai, K. Okawa, N. Sakamoto, and N.-H. Kaneko
   Measurement 225, 114002 (2024).
   
3. "Signal-to-Noise Ratio Optimization for Planar Multijunction Thermal Converters"
   Y. Amagai, K. Okawa, N. Sakamoto, and N.-H. Kaneko
   IEEE Trans. Instrum. Meas. 72, 1003507 (2023).
   
4. "Thermal Analysis of AC-DC Transfer Differences due to the Peltier Effect for Single-Junction Thermal Converters"
   K. Okawa, Y. Amagai, N. Sakamoto, and N.-H. Kaneko
   CPEM Digest (Conference on Precision Electromagnetic Measurements) 2022, 1-2 (2022).
   
5. "A straightforward DC-reversal method for the Thomson coefficient measurement"
   Y. Amagai, T. Shimazaki, K. Okawa, T. Kawae, H. Fujiki, and N.-H. Kaneko
   Measurement 205, 112205 (2022).
   
6. "High-performance stretchable thermoelectric generator using serpentine interconnects encapsulated in an ultrasoft silicone sponge"
   T. Koshi, K. Okawa, Y. Amagai, N. Sakamoto, K. Nomura, M. Yoshida
   Flex. Print. Electron. 7, 125008 (2022).
   
7. "Mathematical Modeling and Measurement of Low Frequency Characteristics of Single-Junction Thermal Converters"
   V. Bubanja, Y. Amagai, K. Okawa, and N.-H. Kaneko
   IEEE Trans. Instrum. Meas. 71, 1500704 (2022).
   
8. "Reverse Heat Flow with Peltier-Induced Thermoinductive Effect"
   K. Okawa, Y. Amagai, H. Fujiki, and N.-H. Kaneko
   Commun. Phys. 4, 267 (2021).
   
9. "Development on measurement method for Thomson coefficient of thin film"
   H. Fujiki, Y. Amagai, K. Okawa , T. Harumoto, and N.-H. Kaneko
   Measurement 185, 110010 (2021).
   
10. "High-accuracy compensation of radiative heat loss in Thomson coefficient measurement"
    Y. Amagai, T. Shimazaki, K. Okawa, T. Kawae, H. Fujiki, and N.-H. Kaneko
    Appl. Phys. Lett. 117, 063903 (2020).
    
11. "Extending the Voltage Range to 10 V RMS value in AC–DC Difference Measurements with an AC-Programmable Josephson Voltage Standard"
    Y. Amagai, M. Maruyama, H. Yamamori, T. Shimazaki, K. Okawa, H. Fujiki, and N.-H. Kaneko
    Meas. Sci. Technol. 31, 065010 (2020).
    
12. "Large-scalable fabrication of improved Bi–Te-based flexible thermoelectric modules using a semiconductor manufacturing process"
    K. Okawa, Y. Amagai, H. Fujiki, N.-H. Kaneko, N. Tsuchimine, H. Kaneko, Y. Tasaki, K. Ohata, M. Okajima, and S. Nambu
    Jpn. J. Appl. Phys. 59, 046504 (2020).
    
13. "Precise absolute Seebeck coefficient measurement and uncertainty analysis using high-T_c superconductors as a reference"
    Y. Amagai, T. Shimazaki, K. Okawa, T. Kawae, H. Fujiki, and N.-H. Kaneko
    Rev. Sci. Instrum. 91, 014903 (2020).
    
14. "Precise measurement of absolute Seebeck coefficient from Thomson effect using ac-dc technique"
    Y. Amagai, T. Shimazaki, K. Okawa, H. Fujiki, T. Kawae, and N.-H. Kaneko
    AIP Advances 9, 065312 (2019).
    
15. "A general route to form topologically-protected surface and bulk Dirac fermions along high-symmetry lines"
    O J Clark, F Mazzola, I Marković, J M Riley, J Feng, B-J Yang, K Sumida, T Okuda, J Fujii, I Vobornik, T K Kim, K Okawa , T Sasagawa, M S Bahramy and P D C King
    Electron. Struct. 1, 014002 (2019).
    
16. "Establishment of High-Voltage AC–DC Voltage Transfer Standards in 1–100-kHz Range at NMIJ"
    H. Fujiki, Y. Amagai, and K. Okawa
    IEEE Trans. Instrum. Meas. 68, 1921 (2019).
    
17. "Low-Frequency AC–DC Differences of a Series–Parallel Circuit of Thermal Converters"
    Y. Amagai, H. Fujiki, K. Okawa, and N.-H. Kaneko
    IEEE Trans. Instrum. Meas. 68, 1907 (2019).
    
18. "Extremely large magnetoresistance induced by hidden three-dimensional Dirac bands in nonmagnetic semimetal InBi"
    K. Okawa, M. Kanou, H. Namiki, T. Sasagawa
    Physical Review Materials 2, 124201 (2018).
    
19. "Fermiology and Superconductivity of Topological Surface States in PdTe₂"
    O. J. Clark, M. J. Neat, K. Okawa, L. Bawden, I. Marković, F. Mazzola, J. Feng, V. Sunko, J. M. Riley, W. Meevasana, J. Fujii, I. Vobornik, T. K. Kim, M. Hoesch, T. Sasagawa, P. Wahl, M. S. Bahramy, and P. D. C. King
    Phys. Rev. Lett. 120, 156401 (2018).
    
20. "Ubiquitous formation of bulk Dirac cones and topological surface states from a single orbital manifold in transition-metal dichalcogenides"
    M. S. Bahramy, O. J. Clark, B.-J. Yang, J. Feng, L. Bawden, J. M. Riley, I. Marković, F. Mazzola, V. Sunko, D. Biswas, S. P. Cooil, M. Jorge, J. W. Wells, M. Leandersson, T. Balasubramanian, J. Fujii, I. Vobornik, J. E. Rault, T. K. Kim, M. Hoesch, K. Okawa, M. Asakawa, T. Sasagawa, T. Eknapakul, W. Meevasana & P. D. C. King
    Nature Materials 17, 21 (2018).
    
21. "Full-gap superconductivity in spin-polarised surface states of topological semimetal β-PdBi₂"
    K. Iwaya, Y. Kohsaka, K. Okawa, T. Machida, M. S. Bahramy, T. Hanaguri & T. Sasagawa
    Nature Communications 8, 976 (2017).
22. "Observation of Nodal Line in Non-symmorphic Topological Semimetal InBi"
    S. A. Ekahana, S-C. Wu, J. Jiang, K. Okawa, D. Prabhakaran, C-C. Hwang, S-K. Mo, T. Sasagawa, C. Felser, B. Yan, Z. Liu, Y. Chen
    New Journal of Physics 19, 065007 (2017).
    
23. “Probing the superconducting gap symmetry of α-PdBi₂: A penetration depth study”
    S. Mitra, K. Okawa, S. K. Sudheesh, T. Sasagawa, J-X. Zhu, E. M. Chia
    Physical Review B 95, 134519 (2017).
    
24. “Topologically protected surface states in a centrosymmetric superconductor β-PdBi₂”
    M. Sakano, K. Okawa, M. Kanou, H. Sanjo, T. Okuda, T. Sasagawa, K. Ishizaka
    Nature Communications 6, 9595 (2015).
    
25. “Crystal Growth and Physical Properties of the Noncentrosymmetric Superconductor PdBi”
    K. Okawa, M. Kanou, T. Katagiri, H. Kashiwaya, S. Kashiwaya, T. Sasagawa
    Physics Procedia 45, 101 (2013).
    

• "Study on Superconducting and Magnetotransport Properties in Single Crystals of Layered Bismuth Compounds with Strong Spin-orbit Coupling”
  Ph.D. Thesis, Department of Innovative and Engineered Materials, Tokyo Institute of Technology, (2017)
Supervisor: Assoc. Prof. Takao Sasagawa

1. "Thermal Analysis of AC-DC Transfer Differences due to the Peltier Effect for Single-Junction Thermal Converters"
   K. Okawa , Y. Amagai, N. Sakamoto, and N.-H. Kaneko
   Conference on Precision Electromagnetic Measurements (CPEM2022), Wellington, New Zealand, December 2022.
   
2. "Comparison of Three Accurate Measurement Methods for Measuring the Efficiency in Thermoelectric Modules"
   K. Okawa , Y. Amagai, H. Fujiki
   37th/16th International and European Conference on Thermoelectrics (ICT2018), P.37, Caen, France, July 2018.
   
3. "Heat Transfer Analysis on the Measurement of Thermoelectric Performances using the Harman Method"
   K. Okawa , Y. Amagai, H. Fujiki
   37th/16th International and European Conference on Thermoelectrics (ICT2018), P.92, Caen, France, July 2018.
   
4. “Substitution and Intercalation Effects in Single Crystals of Candidate Topological Superconductors β-PdBi₂ and PdTe₂”
   K. Okawa , and T. Sasagawa
   28th International Symposium on Superconductivity (ISS2015), PCP-6, Tokyo, Japan, November 2015.
   
5. “Chemical Substitution Effects in Single Crystals of a Candidate Topological Superconductor β-PdBi₂”
   K. Okawa , and T. Sasagawa
   14th International Union of Materials Research Societies-International Conference on Advanced Materials (IUMRS-ICAM 2015), III-6ThP-24, JeJu, Korea, October 2015.
   
6. “Single Crystal Growth and Superconducting Properties of the Layered Compound with Strong Relativistic Effects β-PdBi₂”
   K. Okawa , M. Kanou, T. Sasagawa
   27th International Symposium on Superconductivity (ISS2014), PCP-15, Tokyo, Japan, November 2014.
   
7. “Crystal Growth and Effects of Bi-Deficiency on Normal and Superconducting Properties of Noncentrosymmetric α-PdBi”
   K. Okawa , M. Kanou, T. Katagiri, H. Kashiwaya, S. Kashiwaya, T. Sasagawa
   The 8th International Conference on the Science and Technology for Advanced Ceramics (STAC-8), 26pK21, Yokohama, Japan, June 2014.
   
8. “Anisotropic Properties in Single Crystals of the Noncentrosymmetric Superconductor PdBi”
   K. Okawa , M. Kanou, T. Katagiri, H. Kashiwaya, S. Kashiwaya, T. Sasagawa
   26th International Symposium on Superconductivity (ISS2013), PC-9, Tokyo, Japan, November 2013.
   
9. “Normal and Superconducting Properties in Single Crystals of the Noncentrosymmetric PdBi Compound”
   K. Okawa , M. Kanou, T. Katagiri, H. Kashiwaya, S. Kashiwaya, T. Sasagawa
   11th European Conference on Applied Superconductivity (Eucas2013), 2P-MA4-06, Genova, Italy, September 2013.
   
10. “Normal and Superconducting Properties in Single Crystals of the Noncentrosymmetric PdBi Compound”
    K. Okawa , M. Kanou, T. Katagiri, H. Kashiwaya, S. Kashiwaya, T. Sasagawa
    The International Conference on Strongly Correlated Electron Systems (SCES2013), A-443, Tokyo, Japan, August 2013.
    
11. “Crystal Growth and Physical Properties of Noncentrosymmetric Superconductor PdBi”
    K. Okawa , M. Kanou, T. Katagiri, H. Kashiwaya, S. Kashiwaya, T. Sasagawa
    25th International Symposium on Superconductivity (ISS2012), PCP-28, Tokyo, Japan, December 2012.
    

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