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arXiv 1404.3129cond-mat.mes-hallcond-mat.str-el
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一般螺旋液体的电导率

Conductivity of a generic helical liquid

N. Kainaris, I. V. Gornyi, S. T. Carr, A. D. Mirlin

摘要:

量子自旋霍尔绝缘体是由绝缘体和一维螺旋边缘态组成的二维物质态。虽然这些边缘状态的拓扑保护弹性背散射在无序的存在下,相互作用引起的非弹性条款可能会产生有限的电导率。通过动力学方程方法,我们得到了高($ω\gg τ^{-1}$)和低($ω\ll τ^{-1}$)频率下的背散射率$τ^{-1}$和半经典电导率。通过比较这两个限制,我们发现,参数依赖的电导率描述的德鲁德公式的情况下,一个无序的边缘。另一方面,在清洁的情况下,电阻源于umklapp相互作用,导电性采取非德鲁德形式与参数抑制散射在直流限制相比,交流的情况下。这种行为是由于umklapp散射过程的特殊性,必然涉及在“狄拉克点”的状态。为了考虑到Luttinger液体效应,我们补充了动力学方程分析的玻色子化和计算电导率的Kubo公式处理的相互作用。通过这种方式,我们得到了在很宽的参数范围内的电导率的频率和温度依赖性。我们发现无序系统中输运散射时间的温度和频率依赖性为$τ\sim [\max{(ω,T)}]^{-2K-2}$,对于$K>2/3$和$τ\sim [\max{(ω,T)}]^{-8K+2}$对于$K <2/3$。

英文摘要:

A quantum spin Hall insulator is a two-dimensional state of matter consisting of an insulating bulk and one-dimensional helical edge states. While these edge states are topologically protected against elastic backscattering in the presence of disorder, interaction-induced inelastic terms may yield a finite conductivity. By using a kinetic equation approach, we find the backscattering rate $τ^{-1}$ and the semiclassical conductivity in the regimes of high ($ω\gg τ^{-1}$) and low ($ω\ll τ^{-1}$) frequency. By comparing the two limits, we find that the parametric dependence of conductivity is described by the Drude formula for the case of a disordered edge. On the other hand, in the clean case where the resistance originates from umklapp interactions, the conductivity takes a non-Drude form with a parametric suppression of scattering in the dc limit as compared to the ac case. This behavior is due to the peculiarity of umklapp scattering processes involving necessarily the state at the "Dirac point". In order to take into account Luttinger liquid effects, we complement the kinetic equation analysis by treating interactions exactly in bosonization and calculating conductivity using the Kubo formula. In this way, we obtain the frequency and temperature dependence of conductivity over a wide range of parameters. We find the temperature and frequency dependence of the transport scattering time in a disordered system as $τ\sim [\max{(ω,T)}]^{-2K-2}$, for $K>2/3$ and $τ\sim [\max{(ω,T)}]^{-8K+2}$ for $K <2/3$.

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