Faculty Profiles - KONTANI, Hiroshi

Papers - KONTANI, Hiroshi

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Hall effect and resistivity in high-Tc superconductors: The conserving approximation Reviewed Open Access

H. Kontani, K. Kanki, and K. Ueda

Physical Review B. Vol. 59 ( 22 ) page： 14723-14739 1999.7

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

The Hall coefficient RH in high-Tc cuprates in the normal state shows the striking non-Fermi-liquid behavior: RH follows a Curie-Weiss type temperature dependence and |RH|≫1/|ne| at low temperatures in the underdoped compounds. Moreover, RH is positive for hole-doped compounds and negative for electron-doped ones, although each of them has a similar holelike Fermi surface. In this paper, we give the explanation of this long-standing problem from the standpoint of the nearly antiferromagnetic (AF) Fermi liquid. We consider seriously the vertex corrections for the current which are indispensable to satisfy the conservation laws, which are violated within the conventional Boltzmann transport approximation. The obtained total current Jk takes an enhanced value and is no longer perpendicular to the Fermi surface due to the strong AF fluctuations. By virtue of this mechanism, the anomalous behaviors of RH in high-Tc cuprates are naturally explained. Both the temperature and the (electron, hole) doping dependences of RH in high-Tc cuprates are reproduced well by numerical calculations based on the fluctuation-exchange approximation, applied to the single-band Hubbard model with a holelike Fermi surface. We also discuss the singular temperature dependence of RH in other nearly AF metals, e.g., V2O3, κ-BEDT-TTF organic superconductors, and heavy fermion systems close to the AF phase boundary.

DOI： 10.1103/PhysRevB.59.14723

Hall effect and resistivity in high-T-c superconductors: The conserving approximation Open Access

Kontani H, Kanki K, Ueda K

PHYSICAL REVIEW B Vol. 59 ( 22 ) page： 14723 - 14739 1999.6

Theory of Hall effect and electrical transport in high-T-c cuprates: Effects of antiferromagnetic spin fluctuations Open Access

Kanki K, Kontani H

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 68 ( 5 ) page： 1614 - 1624 1999.5

Effects of spin fluctuations in quasi-one-dimensional organic superconductors Open Access

Kino H, Kontani H

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 68 ( 5 ) page： 1481 - 1484 1999.5

Anomalous Hall effect in Sr2RuO4

Miyazawa M, Kontani H, Yamada E

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 68 ( 5 ) page： 1625 - 1631 1999.5

Phase diagram of superconductivity on the anisotropic triangular lattice Hubbard model: An effective model of kappa-(BEDT-TTF) salts Open Access

Kino H, Kontani H

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 67 ( 11 ) page： 3691 - 3694 1998.11

Phase Diagram of Superconductivity on the Anisotropic Triangular Lattice Hubbard Model: An Effective Model of κ-(BEDT-TTF) Salts Reviewed

Hiori Kino and Hiroshi Kontani

Journal of the Physical Society of Japan Vol. 1998 ( 7 ) page： 3691-3694 1998.7

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

We study the electronic states of the anisotropic triangular lattice Hubbard model at half-filling, which is a simple effective model for the organic superconducting κ-BEDT-TTF compounds. We treat the effect of the Coulomb interaction by the fluctuation exchange (FLEX) method, and obtain the phase diagram of this model for various sets of parameters. It is shown that d-wave superconductivity is realized in a wide region of the phase diagram, next to the antiferromagnetic states. The obtained phase diagram explains well the characteristics of the experimental results.

Electronic properties of the trellis-lattice Hubbard model: Pseudogap and superconductivity

Kontani H, Ueda K

PHYSICAL REVIEW LETTERS Vol. 80 ( 25 ) page： 5619 - 5622 1998.6

Theory of anomalous Hall effect in a heavy fermion system with a strong anisotropic crystal field Open Access

Kontani H, Miyazawa M, Yamada K

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 66 ( 8 ) page： 2252 - 2255 1997.8

Electronic state and magnetic susceptibility in orbitally degenerate (J=5/2) periodic Anderson model Open Access

Kontani H, Yamada K

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 66 ( 8 ) page： 2232 - 2235 1997.8

Quantum fluctuations and frustration of the collinear phase in CaV3O7

Kontani H, Zhitomirsky ME, Ueda K

PHYSICA B Vol. 230 page： 752 - 755 1997.2

Plaquette resonating-valence-bond ground state of CaV4O9

Ueda K, Troyer M, Kontani H, Sigrist M, Lee PA

JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. 29 page： S128 - S130 1996.8

Plaquette resonating-valence-bond ground state of CaV4O9 (vol 76, pg 1932, 1996) Open Access

Ueda K, Kontani H, Sigrist M, Lee PA

PHYSICAL REVIEW LETTERS Vol. 76 ( 24 ) page： 4650 - 4650 1996.6

Effect of quantum fluctuations on magnetic ordering in CaV3O7 Open Access

Kontani H, Zhitomirsky ME, Ueda K

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 65 ( 6 ) page： 1566 - 1569 1996.6

Phase diagram of depleted Heisenberg model for CaV4O9 Open Access

Troyer M, Kontani H, Ueda K

PHYSICAL REVIEW LETTERS Vol. 76 ( 20 ) page： 3822 - 3825 1996.5

Plaquette resonating-valence-bond ground state of CaV4O9 Open Access

Ueda K, Kontani H, Sigrist M, Lee PA

PHYSICAL REVIEW LETTERS Vol. 76 ( 11 ) page： 1932 - 1935 1996.3

Magnetic Susceptibility of the Orbitally Degenerate ( J = 5/2) Periodic Anderson Model - Analysis on the Basis of the Fermi Liquid Theory - Reviewed

Hiroshi Kontani and Kosaku Yamada

Journal of the Physical Society of Japan Vol. 65 ( 1 ) page： 172-188 1996.1

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

In the orbitally degenerate (J= 5/2) Periodic Anderson Model, the magnetic susceptibility is composed of both the Pauli term and the Van Vleck term, as is well known. The former is strongly enhanced by the strong correlation between f-electrons. But, for the latter, the influence of the strong correlation has been obscure for years. In this paper we give the solution of the longstanding problem. With the aid of the d=∞ approximation, we study this problem on the basis of the Fermi liquid theory with degenerate orbitals, taking account of all the vertex corrections in a consistent way. As a result, we obtain the simple expression for the magnetic susceptibility, and show unambiguously that the Van Vleck term is also highly enhanced in the strong correlation regime. This fact explains naturally the enhanced magnetic susceptibility observed in many insulating systems (i.e., Kondo insulator). Moreover, we show that the Wilson ratio takes a value around 1 in the metallic system, in good agreement with experiments.

Plaquette resonating-valence-bond ground state of CaV4O9

Kontani H, Troyer M, Ueda K, Sigrist M, Lee PA

CZECHOSLOVAK JOURNAL OF PHYSICS Vol. 46 page： 1903 - 1904 1996

Theory of Anomalous Hall Effect in Heavy Fermion System Reviewed

Hiroshi Kontani and Kosaku Yamada

Journal of the Physical Society of Japan Vol. 1994 ( 7 ) page： 2627-2652 1994.7

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

The theory of the anomalous Hall effect in the heavy fermion system in the coherent regime is developed on the basis of the periodic Anderson Hamiltonian with degenerate orbitals. The anomalous Hall conductivity arises from the skew-scattering due to the orbital momenta of f-electrons in the presence of magnetic field. By a newly developed analysis based on the phase factor of the f-electron wavefunction in x-y plane, a simple expression for the Hall conductivity σ xy is derived. It makes possible to understand clearly the mechanism and to estimate the sign and the magnitude of the anomalous Hall coefficient. Our theory explains well experimental results in the heavy fermion systems. Finally, we discuss the extension of this theory to explain the temperature dependence of the Hall coefficient in the cuprate high-T c superconductors.

ANOMALOUS HALL-COEFFICIENT IN HEAVY-ELECTRON SYSTEMS Open Access

YAMADA K, KONTANI H, KOHNO H, INAGAKI S

PROGRESS OF THEORETICAL PHYSICS Vol. 89 ( 6 ) page： 1155 - 1166 1993.6

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Papers - KONTANI, Hiroshi