Faculty Profiles - KONTANI, Hiroshi

Papers - KONTANI, Hiroshi

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*Violation of Anderson's Theorem for the Sign-Reversing s-Wave State of Iron-Pnictide Superconductors Invited Reviewed

Seiichiro Onari and Hiroshi Kontani

Physical Review Letters Vol. 103 page： 177001 2009.10

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

Based on the five-orbital model, we study the effect of local impurity in iron pnictides, and find that the interband impurity scattering is promoted by the d-orbital degree of freedom. This fact means that the fully gapped sign-reversing s-wave state, which is predicted by spin fluctuation theories, is very fragile against impurities. In the BCS theory, only 1% impurities with intermediate strength induce huge pair breaking, resulting in the large in-gap state and prominent reduction in Tc, contrary to the prediction based on simple orbital-less models. The present study provides a stringent constraint on the pairing symmetry and the electronic states in iron pnictides.

Anomalous Hall effect in the t2g orbital kagome lattice due to noncollinearity: Significance of the orbital Aharonov-Bohm effect Reviewed

Takeshi Tomizawa and Hiroshi Kontani

Physical Review B Vol. 80 page： 100401 2009.9

Language：English Publishing type：Research paper (scientific journal)

A mechanism of spin structure-driven anomalous Hall effect (AHE) in tilted ferromagnetic metals is proposed by taking account of the d-orbital degree of freedom. We find that a conduction electron acquires a Berry phase due to the complex d-orbital wave function, in the presence of noncollinear spin structure and the spin-orbit interaction. The AHE driven by this orbital-derived Berry phase is much larger than the AHE induced by spin chirality, and it naturally explains the salient features of spin structure-driven AHE in pyrochlore Nd2Mo2O7. Since the proposed AHE can occur even for coplanar spin orders (Mz=0), it is expected to emerge in other interesting geometrically frustrated systems.

Anomalous Hall effect in the t2g orbital kagome lattice due to noncollinearity: Significance of the orbital Aharonov-Bohm effect

Tomizawa Takeshi, Kontani Hiroshi

PHYSICAL REVIEW B Vol. 80 ( 10 ) 2009.9

Anomalous and spin Hall effects in magnetic granular films

Inoue Jun-ichiro, Tanaka Takuro, Kontani Hiroshi

PHYSICAL REVIEW B Vol. 80 ( 2 ) 2009.7

Impurity-induced in-gap state and T-c in sign-reversing s-wave superconductors: analysis of iron oxypnictide superconductors

Senga Yuko, Kontani Hiroshi

NEW JOURNAL OF PHYSICS Vol. 11 2009.3

Unconventional Pairing Originating from the Disconnected Fermi Surfaces of Superconducting LaFeAsO1-xFx (vol 101, 087004, 2008)

Kuroki Kazuhiko, Onari Seiichiro, Arita Ryotaro, Usui Hidetomo, Tanaka Yukio, Kontani Hiroshi, Aoki Hideo

PHYSICAL REVIEW LETTERS Vol. 102 ( 10 ) 2009.3

Unconventional pairing originating from disconnected Fermi surfaces in the iron-based superconductor

Kuroki Kazuhiko, Onari Seiichiro, Arita Ryotaro, Usui Hidetomo, Tanaka Yukio, Kontani Hiroshi, Aoki Hideo

NEW JOURNAL OF PHYSICS Vol. 11 2009.2

Intrinsic Spin Hall Effect in the s-Wave Superconducting State: Analysis of the Rashba Model

Kontani H., Goryo J., Hirashima D. S.

PHYSICAL REVIEW LETTERS Vol. 102 ( 8 ) 2009.2

Intrinsic Spin Hall Effect in the s-Wave Superconducting State: Analysis of the Rashba Model Reviewed

H. Kontani, J. Goryo, and D. S. Hirashima

Physical Review Letters Vol. 102 page： 086602 2009.2

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

A general expression for spin Hall conductivity (SHC) in the s-wave superconducting state at finite temperatures is derived. Based on the expression, we study SHC in a two-dimensional electron gas model in the presence of Rashba spin-orbit interaction (SOI). SHC is zero in the normal state, whereas it takes a large negative value as soon as the superconductivity occurs, due to the change in the quasiparticle contributions. Since this remarkable behavior is independent of the strength of the SOI, it will be widely observed in thin films of superconductors with surface-induced Rashba SOI, or in various noncentrosymmetric superconductors.

Giant extrinsic spin Hall effect due to rare-earth impurities

Tanaka T., Kontani H.

NEW JOURNAL OF PHYSICS Vol. 11 2009.1

Giant Orbital Hall Effect in Transition Metals: Origin of Large Spin and Anomalous Hall Effects

Kontani H., Tanaka T., Hirashima D. S., Yamada K., Inoue J.

PHYSICAL REVIEW LETTERS Vol. 102 ( 1 ) 2009.1

*Giant Orbital Hall Effect in Transition Metals: Origin of Large Spin and Anomalous Hall Effects Invited Reviewed

Vol. 102 page： 016601 2009.1

Minimal model for study on Superconductivity in LaFeAsO1-xFx based on ab-initio downfolding

Arita Ryotaro, Onari Seiichiro, Usui Hidetomo, Kuroki Kazuhiko, Tanaka Yukio, Kontani Hiroshi, Aoki Hideo

25TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT25), PART 5 Vol. 150 2009

Non-Fermi liquid behavior in the magnetotransport of quasi two-dimensional heavy Fermion compounds CeMIn5

Nakajima Y., Shibauchi T., Shishido H., Nakai H., Behnia K., Izawa K., Hedo M., Uwatoko Y., Matsumoto T., Settai R., Onuki Y., Kontani H., Matsuda Y.

JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS Vol. 69 ( 12 ) page： 3261 - 3264 2008.12

Spin Hall effect in Sr2RuO4 and transition metals (Nb,Ta)

Tanaka T., Kontani H., Naito M., Hirashima D. S., Yamada K., Inoue J.

JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS Vol. 69 ( 12 ) page： 3250-3252 2008.12

Impurity Effects in Sign-Reversing Fully Gapped Superconductors: Analysis of FeAs Superconductors

Senga Yuko, Kontani Hiroshi

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 77 ( 11 ) 2008.11

Unconventional superconductivity originating from disconnected Fermi surfaces in the iron-based oxypnictide

Kuroki Kazuhiko, Onari Seiichiro, Arita Ryotaro, Usui Hidetomo, Tanaka Yukio, Kontani Hiroshi, Aoki Hideo

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 77 page： 96-98 2008.11

Intrinsic spin Hall effect in graphene: Numerical calculations in a multiorbital model

Onari Seiichiro, Ishikawa Yasuhito, Kontani Hiroshi, Inoue Jun-ichiro

PHYSICAL REVIEW B Vol. 78 ( 12 ) 2008.9

Unconventional pairing originating from the disconnected Fermi surfaces of superconducting LaFeAsO1-xFx

Kuroki Kazuhiko, Onari Seiichiro, Arita Ryotaro, Usui Hidetomo, Tanaka Yukio, Kontani Hiroshi, Aoki Hideo

PHYSICAL REVIEW LETTERS Vol. 101 ( 8 ) 2008.8

Magnetotransport properties governed by antiferromagnetic fluctuations in the heavy-fermion superconductor CeIrIn5

Nakajima Y., Shishido H., Nakai H., Shibauchi T., Hedo M., Uwatoko Y., Matsumoto T., Settai R., Onuki Y., Kontani H., Matsuda Y.

PHYSICAL REVIEW B Vol. 77 ( 21 ) 2008.6

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