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Nernst Coefficient and Magnetoresistance in High-Tc Superconductors: The Role of Superconducting Fluctuations 査読有り

Hiroshi Kontani

Physical Review Letter 89 巻 ( 23 ) 頁： 237003(4p) 2002年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

In high-Tc cuprates, the Nernst coefficient (ν) as well as the magnetoresistance (Δρ/ρ) increases drastically below the pseudogap temperature, T*, which attracts much attention as a key phenomenon in the pseudogap region. We study these transport phenomena in terms of the fluctuation-exchange+T–matrix approximation. In this present theory, the d-wave superconducting (SC) fluctuations, which are mediated by antiferromagnetic (AF) correlations, become dominant below T*. We especially investigate the vertex corrections both for the charge current and the heat one to keep the conservation laws. As a result, the mysterious behaviors of ν and Δρ/ρ are naturally explained as the reflection of the enhancement of the SC fluctuation, without assuming thermally excited vortices. The present result suggests that the pseudogap phenomena are well described in terms of the Fermi liquid with AF and SC fluctuations.

Theory of magnetoresistance in correlated electron systems: modified Kohler rule in high-T-c superconductors

Kontani H

PHYSICA B-CONDENSED MATTER 312 巻頁： 25 - 27 2002年3月

Theory of Thermoelectric Power in High-Tc Superconductors 査読有り

Hiroshi Kontani

Journal of the Physical Society of Japan 2001 巻 ( 6 ) 頁： 2840-2843 2001年10月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

We present a microscopic theory for the thermoelectric power (TEP) in high-Tc cuprates. Based on the general expression for the TEP, we perform the calculation of the TEP for a two-dimensional Hubbard model including all the vertex corrections necessary to satisfy the conservation laws. In the present study, characteristic anomalous temperature and doping dependences of the TEP in high-Tc cuprates, which have been a long-standing problem in high-Tc cuprates, are well reproduced for both hole- and electron-doped systems, except for the heavily under-doped case. According to the present analysis, the strong momentum and energy dependences of the self-energy due to the strong antiferromagnetic fluctuations play an essential role in reproducing experimental anomalies of the TEP.

Theory of thermoelectric power in high T-c superconductors

Kontani H

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 70 巻 ( 10 ) 頁： 2840 - 2843 2001年10月

General formula for the magnetoresistance on the basis of Fermi liquid theory

Kontani H

PHYSICAL REVIEW B 64 巻 ( 5 ) 2001年8月

General formula for the magnetoresistance on the basis of Fermi liquid theory 査読有り

Hiroshi Kontani

Physical Review B. 64 巻 ( 5 ) 頁： 054413(19p) 2001年8月

Magnetoresistance in High-Tc Superconductors: The Role of Vertex Corrections 査読有り

Hiroshi Kontani

Journal of the Physical Society of Japan 70 巻 ( 7 ) 頁： 1873-1876 2001年7月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

In high-Tc cuprates, the orbital magnetoresistance in plane (Δρ/ρ) is anomalously enhanced at lower tempemeratures compared with conventional Fermi liquids, and thus Kohler's rule is strongly violated. Moreover, it should be noted that an intimate relation between Δρ/ρ and the Hall coefficient (RH), Δρ/ρ ∝ (RH/ρ)2, holds well experimentally, and is called the “modified Kohler's rule". In this letter, we study this long-standing problem in terms of the nearly antiferromagnetic (AF) Fermi liquid. We analyze the exact expression for Δρ/ρ by including the vertex corrections (VC's) to keep the conservation laws, and find the approximate relation Δρ/ρ ∝ ξAF4 ρ-2 · H2 (ξAF being the AF correlation length) in the presence of AF fluctuations. The factor ξAF4, which comes from the VC's for the current, gives the additional temperature dependence. By taking account of the relation RH ∝ ξAF2 [Kontani et al.: Phys. Rev. B 59 (1999) 14723], we can naturally explain the modified Kohler's rule. In conclusion, based on the Fermi liquid theory, the famous seemingly non-Fermi liquid behaviors of RH and Δρ/ρ in high-Tc cuprates are naturally understood on an equal footing.

Possible appearance of superconductivity on Si(100) surface

Kino H, Kontani H

SURFACE SCIENCE 482 巻頁： 501 - 506 2001年6月

Theory of the Hall coefficient and resistivity for the layered organic superconductors kappa-(BEDT-TTF)(2)X

Kontani H, Kino H

PHYSICAL REVIEW B 63 巻 ( 13 ) 2001年4月

Comment on "Charge-orbital stripe structure in La1-xCaxMnO3 (x=1/2, 2/3)" - Reply

Mutou T, Kontani H

PHYSICAL REVIEW LETTERS 86 巻 ( 11 ) 頁： 2479 - 2479 2001年3月

Comment on "Charge-orbital stripe structure in La1-xCaxMnO3 (x=1/2, 2/3)"

Hotta T, Dagotto E, Koizumi H, Takada Y

PHYSICAL REVIEW LETTERS 86 巻 ( 11 ) 頁： 2478 - 2478 2001年3月

Hall effect in high-T-c superconductors

Kontani H, Kanki K, Ueda K

JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS 62 巻 ( 1-2 ) 頁： 83 - 87 2001年

Possible appearance of superconductivity on Si(001) surface

Kino H, Kontani H

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 69 巻 ( 7 ) 頁： 1962 - 1965 2000年7月

Origin of the charge-ordered stripe with the orbital ordering in manganese oxides

Mutou T, Kontani H

PHYSICA B 281 巻頁： 531 - 533 2000年6月

Anomalous behaviors of the transport phenomena in high-T-c superconductors

Kontani H, Kanki K, Ueda K

PHYSICA B 281 巻頁： 808 - 809 2000年6月

Charge-orbital stripe structure in La1-xCaxMnO3 (x=1/2, 2/3)

Mutou T, Kontani H

PHYSICAL REVIEW LETTERS 83 巻 ( 18 ) 頁： 3685 - 3688 1999年11月

Effects of spin fluctuations and superconductivity in quasi-one-dimensional organic conductors

Kino H, Kontani H

JOURNAL OF LOW TEMPERATURE PHYSICS 117 巻 ( 3-4 ) 頁： 317 - 321 1999年11月

Hall effect and resistivity in high-Tc superconductors: The conserving approximation 査読有り

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

Physical Review B. 59 巻 ( 22 ) 頁： 14723-14739 1999年7月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

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.

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

Kontani H, Kanki K, Ueda K

PHYSICAL REVIEW B 59 巻 ( 22 ) 頁： 14723 - 14739 1999年6月

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

Kanki K, Kontani H

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 68 巻 ( 5 ) 頁： 1614 - 1624 1999年5月

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