Wataru KOBAYASHI
Affiliation: Division of Physics, Faculty of pure and applied sciences, University of Tsukuba, Assistant professor
Address: Tennodai 1-1-1, Tsukuba-city, Ibaraki 305-8571
Tel&Fax: +81-2-9853-4276
E-mail: kobayashi.wataru.gf_at_u.tsukuba.ac.jp
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Researchers Information
CV
Apr.1997 - Mar.2001 Department of Physics, School of Science and Engineering,
Waseda University, B.S.
Apr.2001 - Aug.2002 Graduate School of Pure and Applied Physics, Waseda University, M.S.
Sep.2002 - Oct.2005 Graduate School of Pure and Applied Physics, Waseda University, Ph.D
Thesis: “High-temperature quantum phenomena of A-site ordered transition-metal oxides in strongly correlated electron system” (in Japanese), Supervisor: Professor Ichiro Terasaki
Apr.2003 - Mar.2006 JSPS Research Fellowship for Young Scientists DC1->PD
Apr.2006 - Sep.2006 Visiting lecturer, Waseda University
Oct.2006 - Dec.2007 Postdoctoral researcher, CRISMAT laboratory, France
Dec.2007 - Aug.2010 Assistant Professor, Waseda Institute for Advanced Study,
Waseda University
Sep.2010 - current Assistant Professor, Division of Physics, Faculty of pure and applied sciences, University of Tsukuba
Research field
condensed matter physics, quantum transport
Awards
Jan.2017 Young faculty member award, University of Tsukuba
Feb.2011 JPSJ Papers of Editors' choice award (co-author)
Dec.2008 IUMRS-ICA2008 Young Researcher Award
Aug.2006 Presentation award, thermoelectric society of Japan
Member
Dec.2008 - current facilitator of society for new magnetic materials
Apr.2021 - Mar.2025 class teacher
Jul.2012 - Aug.2024 councilor of The Thermoelectrics Society of Japan
Lectures
Advanced course for strongly correlated system IA (even years from 2012)
Advanced course for strongly correlated system IB (even years from 2012)
Problem-seeking seminar (2022, 2023)
Experiments II (X-ray diffraction) (every years from 2011)
Notice for (foreign) students
I'm sorry, but currently I don't accept any (foreign) student.
Selected papers
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W. Kobayashi,
"Analytical expression of negative differential thermal resistance in a macroscopic heterojunction"
J. Stat. Mech., 023204 (2024).
doi.org/10.1088/1742-5468/ad1beb
arXiv:2302.14065
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W. Kobayashi,
"Thermopower in transition-metal perovskites"
Phys. Rev. B 104, 245108 (2021).
doi.org/10.1103/PhysRevB.104.245108
arXiv:2109.07769
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W. Kobayashi,
"Thermal-rectification coefficients in solid-state thermal rectifiers"
Phys. Rev. E 102, 032142 (2020).
doi.org/10.1103/PhysRevE.102.032142
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W. Kobayashi, A. Yanagita, T. Akaba, T. Shimono, D. Tanabe, and Y. Moritomo,
"Thermal Expansion in Layered NaxMO2"
Sci. Rep. 8, 3988 (2018).
doi.org/10.1038/s41598-018-22279-9
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T. Shibata, Y. Fukuzumi, W. Kobayashi, and Y. Moritomo,
"Thermal power generation during heat cycle near room temperature"
Appl. Phys. Exp. 11, 017101 (2018).
doi.org/10.7567/APEX.11.017101
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S. Akama, W. Kobayashi, K. Amaha, H. Niwa, H. Nitani, and Y. Moritomo,
"Local structures around the substituted elements in mixed layered oxides"
Sci. Rep. 7, 43791 (2017).
doi.org/10.1038/srep43791
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K. Amaha, W. Kobayashi, S. Akama, K. Mitsuishi, and Y. Moritomo,
"Interrelation between inhomogeneity and cyclability in O3-NaFe1/2Co1/2O2"
Physica Status Solidi (RRL) 11, 1600284 (2017).
doi.org/10.1002/pssr.201600284
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W. Kobayashi, A. Kinoshita, and Y. Moritomo,
"Seebeck effect in a battery-type thermocell"
Appl. Phys. Lett. 107, 073906 (2015).
doi.org/10.1063/1.4928336
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T. Shibata, Y. Fukuzumi, W. Kobayashi, and Y. Moritomo,
"Fast discharge process of layered cobalt oxides due to high Na+ diffusion"
Sci. Rep. 5, 9006 (2015).
doi.org/10.1038/srep09006
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W. Kobayashi and Y. Moritomo,
"Ionic model approach to battery voltage of NaMO2"
J. Phys. Soc. Jpn. 83, 104712 (2014).
doi.org/10.7566/JPSJ.83.104712
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T. Shibata, W. Kobayashi, and Y. Moritomo,
"Sodium ion diffusion in layered NaxMnO2 (0.49 ≤ x ≤ 0.75): Comparison with NaxCoO2"
Appl. Phys. Express 7, 067101 (2014).
doi.org/10.7567/APEX.7.067101
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T. Shibata, W. Kobayashi, and Y. Moritomo,
"Intrinsic rapid Na+ intercalation observed in NaxCoO2 thin film"
AIP Advances 3, 032104 (2013).
doi.org/10.1063/1.4794719
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W. Kobayashi, D. Sawaki, T. Omura, T. Katsufuji, Y. Moritomo, and I. Terasaki,
"Thermal rectification in the vicinity of a structural phase transition"
Appl. Phys. Express 5, 027302 (2012).
doi.org/10.1143/APEX.5.027302
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W. Kobayashi, Y. Koizumi, and Y. Moritomo,
"Large thermal Hall coefficient in bismuth"
Appl. Phys. Lett. 100, 011903 (2012).
doi.org/10.1063/1.3673562
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W. Kobayashi, Y. Hayashi, M. Matsushita, H. Yamamoto, I. Terasaki, A. Nakao, H. Nakao, T. Murakami, Y. Moritomo, H. Yamauchi, and M. Karppinen,
"Anisotropic thermoelectric properties of quasi-one-dimensional SrNbO3.4+d (d~ 0.03)"
Phys. Rev. B 84, 085118 (2011).
doi.org/10.1103/PhysRevB.84.085118
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D. Sawaki, W. Kobayashi, Y. Moritomo, and I. Terasaki,
"Thermal rectification in bulk materials with asymmetric shape"
Appl. Phys. Lett. 98, 081915 (2011).
doi.org/10.1063/1.3559615
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W. Kobayashi,
"Transport properties of quasi-one-dimensional KRu4O8"
Phys. Rev. B 79, 085207 (2009).
doi.org/10.1103/PhysRevB.79.155116
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W. Kobayashi, Y. Teraoka, and I. Terasaki,
"An oxide thermal rectifier"
Appl. Phys. Lett. 95, 171905 (2009).
doi.org/10.1063/1.3253712
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W. Kobayashi, S. Hebert, O. Perez, D. Pelloquin, and A. Maignan,
"Metallicity in crystals of the quasi 1D rhodate Ba1.2Rh8O16"
Phys. Rev. B 79, 085207 (2009).
doi.org/10.1103/PhysRevB.79.085207
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W. Kobayashi, W. Tamura, and I. Terasaki,
"Thermal conductivity of thermoelectric rhodium oxides measured by a modified Harman method"
J. Phys. Soc. Jpn. 77, 074606 (2008).
doi.org/10.1143/JPSJ.77.074606
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W. Kobayashi, S. Hebert, D. Pelloquin, O. Perez, and A. Maignan,
"Enhanced thermoelectric properties in a two-dimensional rhodium oxide with a trigonal symmetry"
Phys. Rev. B 76, 245102 (2007).
doi.org//10.1103/PhysRevB.76.245102
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W. Kobayashi, S. Ishiwata, I. Terasaki, M. Takano, I. Grigoraviciute, H. Yamauchi, and M. Karppinen,
"Room-temperature ferromagnetism in Sr1-xYxCoO3-d (0.2 <= x <= 0.25)"
Phys. Rev. B 72, 104408 (2005).
doi.org/10.1103/PhysRevB.72.104408
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W. Kobayashi and I. Terasaki,
"CaCu3Ti4O12/CaTiO3 composite dielectrics: Ba/Pb-free dielectric ceramics with high dielectric constants"
Appl. Phys. Lett. 87, 032902 (2005).
doi.org/10.1063/1.1997278
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W. Kobayashi, I. Terasaki, J. Takeya, I. Tsukada, and Yoichi Ando,
"A novel heavy fermion state in CaCu3Ru4O12"
J. Phys. Soc. Jpn. 73, 2373 (2004).
doi.org/10.1143/JPSJ.73.2373
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W. Kobayashi, I. Terasaki, M. Mikami, R. Funahashi, T. Nomura and T. Katsufuji,
"Universal charge transport of the Mn oxides in the high temperature limit"
J. Appl. Phys. 95, 6825 (2004).
doi.org/10.1063/1.1687532
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W. Kobayashi, A. Satake, and I. Terasaki,
"Thermoelectric Properties of the Brownmillerite Oxide Ca2-yLayCo2-xAlxO5 "
Jpn. J. Appl. Phys. 41, 3025 (2002).
doi.org/10.1143/JJAP.41.3025
Research interests
fundamental research
Quantum many body system (intelligence, unconventional superconductivity, non-Fermi liquid, quantum information, quantum gravity)
Non-equilibrium thermodynamics (from quantum to classical including biophysics)
Calculation of phenomenological coefficients based on quantum statistical mechanics
application
Cross correlation in between fluxes and control of the fluxes
Transport phenomena in thermocell (ion, redox)
Themoelectric transport in thermoelectrics (charge, spin, orbital)
Thermal control under magnetic field in semimetals with high mobility (relativistic)
Thermal transport in thermal diode
Chemical potential and ionic transport in secondary-battery
Research content (2002-->current)
fundamental (experimental) point of view (2003-->2012)
heavy fermion --> spin crossover --> non-Fermi liquid --> relativistic
applicational (experimental) point of view (2002-->2024)
thermoelectrics --> thermal diode --> thermal Hall (2002-->2012)
3d: perovskite Co, Mn, Ti, layered Co oxides
4d: quasi 1D Nb, perovskite Ru, layered Rh, quasi 1D Rh oxides
5d: quasi 1D Ir oxide
6s: Bi
others [dielectrics, spin Seebeck effect (joint-research)] (2002-2005, 2012)
Na-ion battery (thin film, voltage, diffusion coefficient, (local) structure, cyclability) --> thermocell (thermogalvanic) (2013-->2024)
3d: P2-NaxMO2, O3-NaMO2, Prussian-Blue analogues with Fe(CN)6
theoretical point of view (2014-->current)
battery voltage --> thermal expansion --> thermal rectification --> thermopower --> negative differential thermal resistance
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