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arXiv 0710.3474cond-mat.mes-hall
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自旋Tomonaga-Luttinger液体中单个杂质输运的数值研究

Numerical study of transport through a single impurity in a spinful Tomonaga-Luttinger liquid

Yuji Hamamoto, Ken-Ichiro Imura, Takeo Kato

摘要:

本文用路径积分蒙特卡罗方法对有自旋的Tomonaga-Luttinger液体中的单杂质问题进行了数值研究。我们的方法的优点是,该系统允许在非微扰制度的电荷和自旋电导进行广泛的分析。通过仔细研究电导在低温下的行为,在有限的后向散射障碍的存在下,由于杂质,我们确定了四个不同的阶段,其特征在于无论是完美的传输或反射的电荷和自旋通道。我们的中间散射强度的相图是一致的弱和强后向散射的限制与标准微扰重整化群(RG)分析,在这个意义上说,我们所有的相边界插值的两个极限情况。然而,进一步的研究表明,我们的相边界的精确位置和形式并不能用标准的RG分析来解释,例如,相图的某些部分看起来非常类似于弱反向散射极限,而另一些部分则明显地来自相反的极限。为了更直观地解释这种行为,我们还从量子布朗运动图像的角度重新考虑了我们的杂质问题。

英文摘要:

The single impurity problem in a spinful Tomonaga-Luttinger liquid is studied numerically using path-integral Monte Carlo methods. The advantage of our approach is that the system allows for extensive analyses of charge and spin conductance in the non-perturbative regime. By closely examining the behavior of conductances at low temperatures, in the presence of a finite backward scattering barrier due to the impurity, we identified four distinct phases characterized by either perfect transmission or reflection of charge and spin channels. Our phase diagram for an intermediate scattering strength is consistent with the standard perturbative renormalization group (RG) analysis in the limit of weak and strong backward scattering, in the sense that all our phase boundaries interpolate the two limiting cases. Further investigations show, however, that precise location and form of our phase boundaries are not trivially explained by the standard RG analysis, e.g., some part of the phase diagram looks much similar to the weak backscattering limit, whereas some other part is clearly derived from the opposite limit. In order to give a more intuitive interpretation of such behaviors, we also reconsidered our impurity problem from the viewpoint of a quantum Brownian motion picture.

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