Theoretical study of the heavy electron state in Lanthanide and Actinide compounds

镧系和锕系化合物重电子态的理论研究

基本信息

  • 批准号:
    62540258
  • 负责人:
  • 金额:
    $ 1.15万
  • 依托单位:
  • 依托单位国家:
    日本
  • 项目类别:
    Grant-in-Aid for General Scientific Research (C)
  • 财政年份:
    1987
  • 资助国家:
    日本
  • 起止时间:
    1987 至 1988
  • 项目状态:
    已结题

项目摘要

The f electron system in most of Lanthanide and Actinide compounds is considered as a localized electron system. However, in some of the compounds such as CeCu_2Si_2 and UBe_<13> in these groups behaves as a Fermiliquid with an extremely large effective mass at low temperatures. This Fermi liquid state is called the heavy electron state. To understand the origin and nature of this state is one of the most fundamental problems in solid state physics.Our major purpose of the present project is to understand the low energy electronic state of the heavy electron system. For this purpose we calculated the density of states in the low energy region using the periodic Anderson model. The obtained result shows that a very sharp peak in the density of states curve appears near the Fermi level at low temperatures when the large renormalization effect due to the f electron spin fluctuations exists in the self-energy correction for the f and s electrons in the system. This narrow band corresponds to the well-defined one-fermion excitation with a very large effective mass. As temperature increases, our calculation shows that the narrow peak broadens and its height decreases due to a shortening of the quasi-particle lifetime. This result is consistent with the experimental result observed in the heavy electon systems which shows the crossover from the heavy electon state to the Kondo-impurity-like state.We also investigated the mechanism of superconductivity in the hight superconducting oxides because we believe that the superconducting oxides are classified into the heavy-electron superconductors. We proposed a possible mechanism for high temperature superconductivity based on the charge-fluctuation-mechanism. The anomalous temperature dependence of the nuclear relaxation time-of cu nucleus in YBCO was successfully explained.
大多数镧系和锕系化合物中的f电子系统被认为是定域电子系统。然而,在某些化合物中,如CeCu_2Si_2和UBe_3,它们<13>在低温下表现为具有极大有效质量的费米液体。这种费米液态被称为重电子态。重电子态的起源和性质是固体物理学中最基本的问题之一,本课题的主要目的是研究重电子系统的低能电子态。为此,我们用周期安德森模型计算了低能区的态密度。结果表明,当系统中f电子和s电子的自能修正存在由f电子自旋涨落引起的大的重整化效应时,低温下态密度曲线在费米能级附近出现一个非常尖锐的峰.这个窄带对应于具有非常大的有效质量的定义明确的单费米子激发。随着温度的升高,我们的计算表明,由于准粒子寿命的缩短,窄峰加宽,其高度降低。这一结果与在重电子系统中观察到的从重电子态到近藤类杂质态的跃迁的实验结果相一致.我们还研究了高超导氧化物的超导电性机制,因为我们认为超导氧化物是重电子超导体.基于电荷涨落机制,提出了一种可能的高温超导机制。成功地解释了YBCO中Cu核弛豫时间与温度的反常关系。

项目成果

期刊论文数量(37)
专著数量(0)
科研奖励数量(0)
会议论文数量(0)
专利数量(0)
T.Koyama and M. Tachiki: Phys. Rev.B. 36. 437-451 (1987)
T.Koyama 和 M. Tachiki:物理学。
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M.Tachiki.: to be published in Solid State Communication.
M.Tachiki.:将发表在《固态通讯》上。
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T. Koyama: "Theory for the Heavy-Fermion State in Anderson Lattice" Jpn. J. Appl. Phys.Suppl. 26. 473-474 (1987)
T. Koyama:“安德森格子中的重费米子态理论”Jpn。
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M. Tachiki: "Charge-fluctuation mechanism of high-T_c superconductivity and the isotope effect in oxide superconductors" Phys. Rev. B. 39. 293-299 (1989)
M. Tachiki:“高温超导的电荷涨落机制和氧化物超导体中的同位素效应” Phys。
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T.Koyama.: Jpn.J.Appl.Phys.26. Suppl.26. 473-474 (1987)
T.Koyama.:Jpn.J.Appl.Phys.26。
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TACHIKI Masashi其他文献

TACHIKI Masashi的其他文献

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{{ truncateString('TACHIKI Masashi', 18)}}的其他基金

Science for High-Tc Superconductors
高温超导体科学
  • 批准号:
    04240101
  • 财政年份:
    1992
  • 资助金额:
    $ 1.15万
  • 项目类别:
    Grant-in-Aid for Scientific Research on Priority Areas
Effects of Layer Structure in High Temperature Superconducting Oxides
高温超导氧化物中层结构的影响
  • 批准号:
    03640328
  • 财政年份:
    1991
  • 资助金额:
    $ 1.15万
  • 项目类别:
    Grant-in-Aid for General Scientific Research (C)
Theoretical Studies on Electronic State and Superconductivity in Oxide Superconductors
氧化物超导体电子态与超导性的理论研究
  • 批准号:
    01540289
  • 财政年份:
    1989
  • 资助金额:
    $ 1.15万
  • 项目类别:
    Grant-in-Aid for General Scientific Research (C)

相似海外基金

Experimental Studies of Anderson Lattice Systems
安德森晶格系统的实验研究
  • 批准号:
    8005099
  • 财政年份:
    1980
  • 资助金额:
    $ 1.15万
  • 项目类别:
    Continuing grant
Experimental Studies of Anderson Lattice Systems
安德森晶格系统的实验研究
  • 批准号:
    7821750
  • 财政年份:
    1979
  • 资助金额:
    $ 1.15万
  • 项目类别:
    Continuing Grant
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