Nao Takeshita

National Institute of Advanced Industrial Science and Technology

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National Institute of Advanced Industrial Science and Technology

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Research Subjects

Superconductivity

Research Interests

Nao Takeshita has a total of 494 co-authors. Here are the top co-authors by number of shared publications:

Akira Iyo
National Institute of Advanced Industrial Science and Technology (AIST)
33 shared publications
Hiroshi Eisaki
16 shared publications
H. Takagi
Tokyo University
14 shared publications
N. Môri
Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8581, Japan
12 shared publications
Nobuo Môri
Institute for Solid State Physics (ISSP), University of Tokyo, Chiba 277-8581
12 shared publications
Shigeyuki Ishida
National Institute of Advanced Industrial Science and Technology
12 shared publications

Latest Publications

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- 20 February 2026
- Published by Taylor & Francis in High Pressure Research
AC Magnetization measurements of a Hg-based cuprate superconductor at high pressure using various pressure transmitting media
by Masaki Mito, Sin-Nosuke Maeda, Kazuhira Shoji, Kazuma Tsutsumi, Kazuma Ogata, Nao Takeshita, Ayako Yamamoto
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- 20 February 2026
- Published by Taylor & Francis in High Pressure Research
AC Magnetization measurements of a Hg-based cuprate superconductor at high pressure using various pressure transmitting media
by Masaki Mito, Sin-Nosuke Maeda, Kazuhira Shoji, Kazuma Tsutsumi, Kazuma Ogata, Nao Takeshita, Ayako Yamamoto
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- 16 June 2025
- Published by American Physical Society (APS) in Physical Review B
Superconductivity of ${Sc}_{20} {BC}_{27}$ at ambient and under applied pressure conditions
by G. Lamura, H. Ninomiya, R. Khasanov, K. Kawashima, N. Takeshita, H. Ogino, T. Shiroka
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- 16 June 2025
- Published by American Physical Society (APS) in Physical Review B
Superconductivity of ${Sc}_{20} {BC}_{27}$ at ambient and under applied pressure conditions
by G. Lamura, H. Ninomiya, R. Khasanov, K. Kawashima, N. Takeshita, H. Ogino, T. Shiroka
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Cited by 4
- 15 October 2024
- Published by Physical Society of Japan in Journal of the Physical Society of Japan
Doping Dependence of Upper Critical Field of High-T_c Cuprate Bi₂₊_xSr₂₋_xCaCu₂O₈₊_δ Estimated from Irreversibility Field at Zero Temperature
by Junichiro Kato, Shigeyuki Ishida, Tatsunori Okada, Shungo Nakagawa, Yutaro Mino, Yoichi Higashi, Takanari Kashiwagi, Satoshi Awaji, Akira Iyo, Hiraku Ogino, et al.
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- 15 October 2024
- Published by Physical Society of Japan in Journal of the Physical Society of Japan
Doping Dependence of Upper Critical Field of High-T_c Cuprate Bi₂₊_xSr₂₋_xCaCu₂O₈₊_δ Estimated from Irreversibility Field at Zero Temperature
by Junichiro Kato, Shigeyuki Ishida, Tatsunori Okada, Shungo Nakagawa, Yutaro Mino, Yoichi Higashi, Takanari Kashiwagi, Satoshi Awaji, Akira Iyo, Hiraku Ogino, et al.
Cited by 4
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Cited by 4
- 15 April 2024
- Published by Physical Society of Japan in Journal of the Physical Society of Japan
Single-Crystal Growth and Characterization of Cuprate Superconductor (Hg,Re)Ba₂Ca₂Cu₃O₈₊_δ
by Yutaro Mino, Shigeyuki Ishida, Junichiro Kato, Shungo Nakagawa, Takanari Kashiwagi, Takahiro Nozue, Nao Takeshita, Kunihiro Kihou, Chul-Ho Lee, Taichiro Nishio, et al.
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- 15 April 2024
- Published by Physical Society of Japan in Journal of the Physical Society of Japan
Single-Crystal Growth and Characterization of Cuprate Superconductor (Hg,Re)Ba₂Ca₂Cu₃O₈₊_δ
by Yutaro Mino, Shigeyuki Ishida, Junichiro Kato, Shungo Nakagawa, Takanari Kashiwagi, Takahiro Nozue, Nao Takeshita, Kunihiro Kihou, Chul-Ho Lee, Taichiro Nishio, et al.
Cited by 4
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Cited by 6
- 1 November 2021
- Published by Elsevier in Journal of Alloys and Compounds
Superconductivity of centrosymmetric and non-centrosymmetric phases in antiperovskite (Ca,Sr)Pd3P
by Akira Iyo, Izumi Hase, Hiroshi Fujihisa, Yoshito Gotoh, Nao Takeshita, Shigeyuki Ishida, Hiroki Ninomiya, Yoshiyuki Yoshida, Hiroshi Eisaki, Hishiro T. Hirose, et al.
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- 1 November 2021
- Published by Elsevier in Journal of Alloys and Compounds
Superconductivity of centrosymmetric and non-centrosymmetric phases in antiperovskite (Ca,Sr)Pd3P
by Akira Iyo, Izumi Hase, Hiroshi Fujihisa, Yoshito Gotoh, Nao Takeshita, Shigeyuki Ishida, Hiroki Ninomiya, Yoshiyuki Yoshida, Hiroshi Eisaki, Hishiro T. Hirose, et al.
Cited by 6
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Cited by 17
- 6 July 2020
- Published by American Physical Society (APS) in Physical Review Materials
Structural, magnetic, transport, and thermoelectric properties of the pseudobrookite ${AlTi}_{2} O_{5} − {Ti}_{3} O_{5}$ system
by Ryusei Takahama, Toi Ishii, Daigo Indo, Mitsutoshi Arizono, Chieko Terakura, Yoshinori Tokura, Nao Takeshita, Masaaki Noda, Hideki Kuwahara, Takuo Saiki, et al.
We investigated the structural, magnetic, transport, and high-temperature thermoelectric properties of single crystals of the pseudobrookite ${Al}_{1 - x} {Ti}_{2 + x} O_{5}$ for $0 \leq x \leq 1$ grown using a floating zone. We found a correlation of spin-singlet ${Ti}^{3 +} − {Ti}^{3 +}$ dimers coupled with the lattice even in the conductive $α$ and $λ$ phases which develops with increasing $x$ . This developing dimer correlation reduces the number of unpaired ${Ti}^{3 +}$ ions, which makes the compound more conductive owing to the suppression of disorder for $x$ up to about 0.75. The dimer fluctuation causes a critical enhancement of the magnetic susceptibility at around 150 K in the $λ$ phase near the boundary ( $x \sim 0.9$ ) between the $λ$ and the $β$ phases. Such a correlation of the spin-singlet ${Ti}^{3 +} − {Ti}^{3 +}$ dimers may produce a high Seebeck coefficient in the conductive $α$ and $λ$ phases leading to a large thermoelectric power factor at high temperatures.
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- 6 July 2020
- Published by American Physical Society (APS) in Physical Review Materials
Structural, magnetic, transport, and thermoelectric properties of the pseudobrookite ${AlTi}_{2} O_{5} − {Ti}_{3} O_{5}$ system
by Ryusei Takahama, Toi Ishii, Daigo Indo, Mitsutoshi Arizono, Chieko Terakura, Yoshinori Tokura, Nao Takeshita, Masaaki Noda, Hideki Kuwahara, Takuo Saiki, et al.
We investigated the structural, magnetic, transport, and high-temperature thermoelectric properties of single crystals of the pseudobrookite ${Al}_{1 - x} {Ti}_{2 + x} O_{5}$ for $0 \leq x \leq 1$ grown using a floating zone. We found a correlation of spin-singlet ${Ti}^{3 +} − {Ti}^{3 +}$ dimers coupled with the lattice even in the conductive $α$ and $λ$ phases which develops with increasing $x$ . This developing dimer correlation reduces the number of unpaired ${Ti}^{3 +}$ ions, which makes the compound more conductive owing to the suppression of disorder for $x$ up to about 0.75. The dimer fluctuation causes a critical enhancement of the magnetic susceptibility at around 150 K in the $λ$ phase near the boundary ( $x \sim 0.9$ ) between the $λ$ and the $β$ phases. Such a correlation of the spin-singlet ${Ti}^{3 +} − {Ti}^{3 +}$ dimers may produce a high Seebeck coefficient in the conductive $α$ and $λ$ phases leading to a large thermoelectric power factor at high temperatures.
Cited by 17
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Cited by 13
- 26 December 2019
- Published by American Physical Society (APS) in Physical Review Materials
Superconductivity induced by Mg deficiency in noncentrosymmetric phosphide ${Mg}_{2} {Rh}_{3} P$
by Akira Iyo, Izumi Hase, Hiroshi Fujihisa, Yoshito Gotoh, Nao Takeshita, Shigeyuki Ishida, Hiroki Ninomiya, Yoshiyuki Yoshida, Hiroshi Eisaki, Kenji Kawashima
The search for noncentrosymmetric superconductors that may exhibit unusual physical properties and unconventional superconductivity has yielded the synthesis of a noncentrosymmetric phosphide ${Mg}_{2} {Rh}_{3} P$ with an $A l_{2} M o_{3} C$ -type structure. Although stoichiometric ${Mg}_{2} {Rh}_{3} P$ does not exhibit superconductivity at temperatures above 2 K, we found that an Mg deficiency of approximately 5 at.% in the ${Mg}_{2} {Rh}_{3} P$ -induced superconductivity at 3.9 K. Physical properties such as the lattice parameter $a = 7.0881 Å$ , Sommerfeld constant $γ_{n} = 5.36 mJ mo l^{- 1} K^{- 2}$ , specific heat jump $Δ C_{el} / γ_{n} T_{c} = 0.72$ , electron–phonon coupling constant $λ_{e - p} = 0.58$ , upper critical field $H_{c 2} (0) = 24.3 kOe$ , and pressure effect $d T_{c} / d P = - 0.34 K / GPa$ were measured for the superconducting ${Mg}_{2 - δ} {Rh}_{3} P$ ( $δ \sim 0.1$ ). Band-structure calculations indicate that exotic fermions, which are not present in high-energy physics, exist in ${Mg}_{2} {Rh}_{3} P$ . Since Mg, Rh, and P are the first elements used at each crystal site of $A l_{2} M o_{3} C$ -type compounds, the discovery of ${Mg}_{2} {Rh}_{3} P$ may guide the search for new related materials.
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- 26 December 2019
- Published by American Physical Society (APS) in Physical Review Materials
Superconductivity induced by Mg deficiency in noncentrosymmetric phosphide ${Mg}_{2} {Rh}_{3} P$
by Akira Iyo, Izumi Hase, Hiroshi Fujihisa, Yoshito Gotoh, Nao Takeshita, Shigeyuki Ishida, Hiroki Ninomiya, Yoshiyuki Yoshida, Hiroshi Eisaki, Kenji Kawashima
The search for noncentrosymmetric superconductors that may exhibit unusual physical properties and unconventional superconductivity has yielded the synthesis of a noncentrosymmetric phosphide ${Mg}_{2} {Rh}_{3} P$ with an $A l_{2} M o_{3} C$ -type structure. Although stoichiometric ${Mg}_{2} {Rh}_{3} P$ does not exhibit superconductivity at temperatures above 2 K, we found that an Mg deficiency of approximately 5 at.% in the ${Mg}_{2} {Rh}_{3} P$ -induced superconductivity at 3.9 K. Physical properties such as the lattice parameter $a = 7.0881 Å$ , Sommerfeld constant $γ_{n} = 5.36 mJ mo l^{- 1} K^{- 2}$ , specific heat jump $Δ C_{el} / γ_{n} T_{c} = 0.72$ , electron–phonon coupling constant $λ_{e - p} = 0.58$ , upper critical field $H_{c 2} (0) = 24.3 kOe$ , and pressure effect $d T_{c} / d P = - 0.34 K / GPa$ were measured for the superconducting ${Mg}_{2 - δ} {Rh}_{3} P$ ( $δ \sim 0.1$ ). Band-structure calculations indicate that exotic fermions, which are not present in high-energy physics, exist in ${Mg}_{2} {Rh}_{3} P$ . Since Mg, Rh, and P are the first elements used at each crystal site of $A l_{2} M o_{3} C$ -type compounds, the discovery of ${Mg}_{2} {Rh}_{3} P$ may guide the search for new related materials.
Cited by 13
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Cited by 82
- 3 June 2019
- Published by Springer Nature in npj Quantum Materials
Unique defect structure and advantageous vortex pinning properties in superconducting CaKFe4As4
by Shigeyuki Ishida, Akira Iyo, Hiraku Ogino, Hiroshi Eisaki, Nao Takeshita, Kenji Kawashima, Keiichi Yanagisawa, Yuuga Kobayashi, Koji Kimoto, Hideki Abe, et al.
The lossless current-carrying capacity of a superconductor is limited by its critical current density (J_c). A key to enhance J_c towards real-life applications is engineering defect structures to optimize the pinning landscape. For iron-based superconductors considered as candidate materials for high-field applications, high J_c values have been achieved by various techniques to introduce artificial pinning centres. Here we report extraordinary vortex pinning properties in CaKFe₄As₄ (CaK1144) arising from the inherent defect structure. Scanning transmission electron microscopy revealed the existence of nanoscale intergrowths of the CaFe₂As₂ phase, which is unique to CaK1144 formed as a line compound. The J_c properties in CaK1144 are found to be distinct from other iron-based superconductors characterized by a significant anisotropy with respect to the magnetic field orientation as well as a remarkable pinning mechanism significantly enhanced with increasing temperature. We propose a comprehensive explanation of the J_c properties based on the unique intergrowths acting as pinning centres.
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- 3 June 2019
- Published by Springer Nature in npj Quantum Materials
Open Access
Unique defect structure and advantageous vortex pinning properties in superconducting CaKFe4As4
by Shigeyuki Ishida, Akira Iyo, Hiraku Ogino, Hiroshi Eisaki, Nao Takeshita, Kenji Kawashima, Keiichi Yanagisawa, Yuuga Kobayashi, Koji Kimoto, Hideki Abe, et al.
The lossless current-carrying capacity of a superconductor is limited by its critical current density (J_c). A key to enhance J_c towards real-life applications is engineering defect structures to optimize the pinning landscape. For iron-based superconductors considered as candidate materials for high-field applications, high J_c values have been achieved by various techniques to introduce artificial pinning centres. Here we report extraordinary vortex pinning properties in CaKFe₄As₄ (CaK1144) arising from the inherent defect structure. Scanning transmission electron microscopy revealed the existence of nanoscale intergrowths of the CaFe₂As₂ phase, which is unique to CaK1144 formed as a line compound. The J_c properties in CaK1144 are found to be distinct from other iron-based superconductors characterized by a significant anisotropy with respect to the magnetic field orientation as well as a remarkable pinning mechanism significantly enhanced with increasing temperature. We propose a comprehensive explanation of the J_c properties based on the unique intergrowths acting as pinning centres.
Cited by 82
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Cited by 15
- 22 March 2019
- Published by AIP Publishing in Journal of Applied Physics
Hydrostatic pressure effects on superconducting transition of nanostructured niobium highly strained by high-pressure torsion
by Masaki Mito, Yuichiro Kitamura, Takayuki Tajiri, Kazuma Nakamura, Ryo Shiraishi, Kazuma Ogata, Hiroyuki Deguchi, Tomiko Yamaguchi, Nao Takeshita, Terukazu Nishizaki, et al.
We study the effects of hydrostatic pressure (HP) compression on the superconducting transition of severely strained Nb samples, whose grain sizes are reduced to the submicrometer level. Engineered granularity by high-pressure torsion (HPT) treatment changes the strength of coupling between submicrometer-scale grains and introduces lattice strain. We attempt to utilize the initially accumulated shear strain in the starting material for increasing the superconducting transition temperature $T_{c}$ under HP compression. The HP effects on non-strained Nb have already been investigated in the pressure regime over 100 GPa by Struzhkin et al. [Phys. Rev. Lett. $79$ , 4262 (1997)], and $T_{c}$ reportedly exhibited an increase from 9.2 to 9.9 K at approximately 10 GPa. (1) Slightly strained Nb in the HPT treatment exhibits the increase in $T_{c}$ under HP due to the strengthening of the intergrain coupling, so the pressure scale of the pressure response observed by Struzhkin et al. is reduced to approximately one-seventh at the maximum. (2) Prominently strained Nb in the HPT treatment exhibits the increase in $T_{c}$ under HP due to a reduction in structural symmetry at the unit-cell level: In a Nb sample subjected to HPT (6 GPa, 10 revolutions), $T_{c}$ exceeds 9.9 K at approximately 2 GPa. According to our first-principle calculations, the reduction in the structural symmetry affords an increase in the density of states at the Fermi energy, thereby yielding a prominent increase in $T_{c}$ at low pressures.
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- 22 March 2019
- Published by AIP Publishing in Journal of Applied Physics
Hydrostatic pressure effects on superconducting transition of nanostructured niobium highly strained by high-pressure torsion
by Masaki Mito, Yuichiro Kitamura, Takayuki Tajiri, Kazuma Nakamura, Ryo Shiraishi, Kazuma Ogata, Hiroyuki Deguchi, Tomiko Yamaguchi, Nao Takeshita, Terukazu Nishizaki, et al.
We study the effects of hydrostatic pressure (HP) compression on the superconducting transition of severely strained Nb samples, whose grain sizes are reduced to the submicrometer level. Engineered granularity by high-pressure torsion (HPT) treatment changes the strength of coupling between submicrometer-scale grains and introduces lattice strain. We attempt to utilize the initially accumulated shear strain in the starting material for increasing the superconducting transition temperature $T_{c}$ under HP compression. The HP effects on non-strained Nb have already been investigated in the pressure regime over 100 GPa by Struzhkin et al. [Phys. Rev. Lett. $79$ , 4262 (1997)], and $T_{c}$ reportedly exhibited an increase from 9.2 to 9.9 K at approximately 10 GPa. (1) Slightly strained Nb in the HPT treatment exhibits the increase in $T_{c}$ under HP due to the strengthening of the intergrain coupling, so the pressure scale of the pressure response observed by Struzhkin et al. is reduced to approximately one-seventh at the maximum. (2) Prominently strained Nb in the HPT treatment exhibits the increase in $T_{c}$ under HP due to a reduction in structural symmetry at the unit-cell level: In a Nb sample subjected to HPT (6 GPa, 10 revolutions), $T_{c}$ exceeds 9.9 K at approximately 2 GPa. According to our first-principle calculations, the reduction in the structural symmetry affords an increase in the density of states at the Fermi energy, thereby yielding a prominent increase in $T_{c}$ at low pressures.
Cited by 15
Open Access
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Cited by 11
- 1 March 2018
- Published by IOP Publishing in Journal of Physics: Conference Series
Superconducting state in (Eu1-xCax)RbFe4As4with 1144-type Structure
by K. Kawashima, S. Ishida, K. Oka, H. Kito, N. Takeshita, H. Fujihisa, Y. Gotoh, K. Kihou, H. Eisaki, Y. Yoshida, et al.
We report the Ca substitution effect of the Fe-based superconductor EuRbFe₄As₄ with 1144-type structure (crystal system: tetragonal, space group: P4/mmm (No. 123)), in order to elucidate the relationship between the superconductivity and the magnetic order. The lattice constant systematically changed with the Ca concentration x. By Ca-substitution, the magnetic order is suppressed, while T _c is almost unchanged. The results indicate that the superconductivity of EuRbFe₄As₄ is not sensitive to the magnetic order.
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- 1 March 2018
- Published by IOP Publishing in Journal of Physics: Conference Series
Open Access
Superconducting state in (Eu1-xCax)RbFe4As4with 1144-type Structure
by K. Kawashima, S. Ishida, K. Oka, H. Kito, N. Takeshita, H. Fujihisa, Y. Gotoh, K. Kihou, H. Eisaki, Y. Yoshida, et al.
We report the Ca substitution effect of the Fe-based superconductor EuRbFe₄As₄ with 1144-type structure (crystal system: tetragonal, space group: P4/mmm (No. 123)), in order to elucidate the relationship between the superconductivity and the magnetic order. The lattice constant systematically changed with the Ca concentration x. By Ca-substitution, the magnetic order is suppressed, while T _c is almost unchanged. The results indicate that the superconductivity of EuRbFe₄As₄ is not sensitive to the magnetic order.
Cited by 11

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