Faculty Profiles - KONTANI, Hiroshi

Papers - KONTANI, Hiroshi

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Non-Fermi-liquid transport phenomena and superconductivity driven by orbital fluctuations in iron pnictides: Analysis by fluctuation-exchange approximation

Onari Seiichiro, Kontani Hiroshi

PHYSICAL REVIEW B Vol. 85 ( 13 ) 2012.4

Orbital fluctuation theory in iron-based superconductors: s++-wave superconductivity, structure transition, and impurity-induced nematic order Invited Reviewed

H. Kontani, I. Yoshio. T. Saito, Y. Yamakawa and S. Onari

Solid State Communications Vol. 152 page： 718-727 2012.4

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

The main features in iron-based superconductors would be (i) the orthorhombic transition accompanied by remarkable softening of shear modulus, (ii) high-Tc superconductivity close to the orthorhombic phase, and (iii) nematic transition in the tetragonal phase. In this paper, we present a unified explanation for them, based on the orbital fluctuation theory, considering both the e-ph and the Coulomb interaction. It is found that a small e-ph coupling constant ($\lambda ~ 0.2$) is enough to produce large orbital (=charge quadrupole $O_{xz/yz}$) fluctuations, which causes the s-wave superconductivity without sign reversal ($s_{++}$-wave state). The derived orbital fluctuations also cause the instability toward the structure transition due to the bound state formation of two orbitons with opposite momenta, which is called the "two-orbiton process". Moreover, impurity-induced non-local orbital order with $C_2$-symmetry is obtained when the orbital fluctuations are strong. This "impurity-induced nematic state" explains the in-plane anisotropy of resistivity in detwinned samples. We stress that (i)-(iii) are reproducible only when orbital fluctuations with respect to $O_{xz}$ and $O_{yz}$ charge quadrupoles are the most divergent. This fact ensures the reliability of the present model Hamiltonian and calculation.

Orbital fluctuation theory in iron-based superconductors: s(++)-wave superconductivity, structure transition, and impurity-induced nematic order

Kontani Hiroshi, Inoue Yoshio, Saito Tetsuro, Yamakawa Youichi, Onari Seiichiro

SOLID STATE COMMUNICATIONS Vol. 152 ( 8 ) page： 718-727 2012.4

Study of non-Fermi-liquid-like state and pairing symmetry in iron pnictides based on the multiorbital Hubbard-Holstein model

Onari S., Kontani H.

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Vol. 471 ( 21-22 ) page： 670-674 2011.11

Extremely strong-coupling superconductivity in artificial two-dimensional Kondo lattices

Mizukami Y., Shishido H., Shibauchi T., Shimozawa M., Yasumoto S., Watanabe D., Yamashita M., Ikeda H., Terashima T., Kontani H., Matsuda Y.

NATURE PHYSICS Vol. 7 ( 11 ) page： 849 - 853 2011.11

Neutron inelastic scattering peak by dissipationless mechanism in the s(++)-wave state in iron-based superconductors

Onari Seiichiro, Kontani Hiroshi

PHYSICAL REVIEW B Vol. 84 ( 14 ) 2011.10

Linear decrease of critical temperature with increasing Zn substitution in the iron-based superconductor BaFe1.89-2xZn2xCo0.11As2

Li Jun, Guo Yanfeng, Zhang Shoubao, Yu Shan, Tsujimoto Yoshihiro, Kontani Hiroshi, Yamaura Kazunari, Takayama-Muromachi Eiji

PHYSICAL REVIEW B Vol. 84 ( 2 ) 2011.7

Origin of orthorhombic transition, magnetic transition, and shear-modulus softening in iron pnictide superconductors: Analysis based on the orbital fluctuations theory

Kontani Hiroshi, Saito Tetsuro, Onari Seiichiro

PHYSICAL REVIEW B Vol. 84 ( 2 ) 2011.7

Comment on "Violation of Anderson's Theorem for the Sign-Reversing s-Wave State of Iron-Pnictide Superconductors" Reply

Onari Seiichiro, Kontani Hiroshi

PHYSICAL REVIEW LETTERS Vol. 106 ( 25 ) 2011.6

Indication of intrinsic spin Hall effect in 4d and 5d transition metals

Morota M., Niimi Y., Ohnishi K., Wei D. H., Tanaka T., Kontani H., Kimura T., Otani Y.

PHYSICAL REVIEW B Vol. 83 ( 17 ) 2011.5

Comment on "Orbital Order, Structural Transition and Superconductivity in Iron Pnictides" [J. Phys. Soc. Jpn. 79 (2010) 123707]

Kontani Hiroshi, Onari Seiichiro

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 80 ( 5 ) 2011.5

Emergence of fully gapped s(++)-wave and nodal d-wave states mediated by orbital and spin fluctuations in a ten-orbital model of KFe2Se2

Saito Tetsuro, Onari Seiichiro, Kontani Hiroshi

PHYSICAL REVIEW B Vol. 83 ( 14 ) 2011.4

Emergence of Fully-Gapped s++-wave and Nodal d-wave States Mediated by Orbital- and Spin-Fluctuations in Ten-Orbital Model for KFe2Se2 Reviewed

T. Saito, S. Onari, and H. Kontani

Phys. Rev. B Vol. 83 page： 140512 2011

Extremely strong-coupling superconductivity in artificial two-dimensional Kondo lattices Reviewed

Y. Mizukami, H. Shishido, T. Shibauchi, M. Shimozawa, S. Yasumoto, D. Watanabe, M.Yamashita, H. Ikeda, T. Terashima, H. Kontani, and Y. Matsuda

Nature Physics Vol. 7 page： 849 2011

Neutron inelastic scattering peak by dissipationless mechanism in the s++-wave state in iron-based superconductors Reviewed

S. Onari and H. Kontani

Phys. Rev. B Vol. 84 page： 144518 2011

Linear decrease of critical temperature with increasing Zn substitution in the iron-based superconductor Reviewed

Jun Li, Y. Guo, S. Zhang, S. Yu, Y. Tsujimoto, H. Kontani, K. Yamaura, and E. Takayama-Muromachi

Phys. Rev. B Vol. 84 page： 020513 2011

Origin of Orthorhombic Transition, Magnetic Transition, and Shear Modulus Softening in Iron Pnictide Superconductors: Analysis based on the Orbital Fluctuation Theory Reviewed

H. Kontani, T. Saito, and S. Onari

Phys. Rev. B Vol. 84 page： 024528 2011

Indication of intrinsic spin Hall effect in 4d and 5d transition metals Reviewed

M. Morota, Y. Niimi, K. Ohnishi, T. Tanaka, H. Kontani, T. Kimura, Y. Otani

Phys. Rev. B Vol. 83 page： 174405 2011

Nonmagnetic impurity effects and neutron scattering spectrum in iron pnictides

Onari S., Kontani H.

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Vol. 470 ( 20 ) page： 1007-1009 2010.11

Orbital fluctuation theory in iron pnictides: Effects of As-Fe-As bond angle, isotope substitution, and Z(2)-orbital pocket on superconductivity

Saito Tetsuro, Onari Seiichiro, Kontani Hiroshi

PHYSICAL REVIEW B Vol. 82 ( 14 ) 2010.10

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