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Unconventional low dimensional fluctuation in organic conductors

有机导体非常规的低尺寸波动

基本信息

批准号：
09640429
负责人：
SUZUMURA Yoshikazu
金额：
$ 1.86万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 2000
项目状态：
已结题

项目摘要

We have studied theoretically the following system based on the bosonization in order to study a role of correlation and fluctuation in low dimensional organic conductors. (i) The transition from insulator to metal occurs under pressures in the normal state of Bechgaard salts, which exhibit the charge gap. Such a transition is determined by a ratio of the charge gap to the interchain hopping. The mechanism has been studied by use of two-coupled chains with a half-filled band, in which the one-dimensional fluctuation is treated in terms of the renormalization group method. It is demonstrated that the confinement occurs when the charge gap becomes larger than than the interchain hopping. Further the effect of the electron-filling from the commensurate state has been examined. (2) The spin density wave of organic conductors exhibits a novel transition at temperature of the 1/3 of the critical temperature. By using a phase Hamiltonian for two-coupled chains of SDW, the effect of the phase difference between chain has been investigated by use of the transfer integral method. It is shown that the competition between the commensurability energy and interchain coupling gives rise to the transition from the commensurate state to the incommensurate state. (3) The effect of impurity in two-coupled spinless chain has been studied to understand the role of interchain hopping in quasi-one-dimensional systems. It is found that the one-dimensional localization occurs when the pinning energy of impurity becomes larger than the interaction induced interchain gap. Besides the above results, we have examined the electronic state of one-dimensional electrons, collective modes of spin density wave and the impurity effect on spin Peirls system.

我们从理论上研究了以下基于玻色化的系统，以研究低维有机导体中相关性和涨落的作用。 (i) 在 Bechgaard 盐的正常状态下，在压力下会发生从绝缘体到金属的转变，从而表现出电荷间隙。这种转变由电荷间隙与链间跳跃的比率确定。利用半满带的双耦合链研究了该机理，其中一维波动用重正化群方法处理。事实证明，当电荷间隙变得大于链间跳跃时，就会发生限制。此外，还检验了来自相应状态的电子填充的效果。 (2)有机导体的自旋密度波在1/3临界温度时表现出新的转变。通过对SDW的两个耦合链使用相位哈密顿量，利用传递积分方法研究了链间相位差的影响。结果表明，可通约能量和链间耦合之间的竞争导致了从可通约状态到不可通约状态的转变。 (3) 研究了杂质在两耦合无自旋链中的影响，以了解准一维系统中链间跳跃的作用。研究发现，当杂质的钉扎能大于相互作用引起的链间间隙时，就会发生一维局域化。除了上述结果之外，我们还研究了一维电子的电子态、自旋密度波的集体模式以及自旋 Peirls 系统中的杂质效应。