arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2404.05947cond-mat.mes-hallcond-mat.str-el
收藏

多能级安德森杂质的热电输运与电流噪声:量子点和磁性合金中的三体费米液体修正

Thermoelectric transport and current noise through a multilevel Anderson impurity: Three-body Fermi-liquid corrections in quantum dots and magnetic alloys

Yoshimichi Teratani, Kazuhiko Tsutsumi, Kaiji Motoyama, Rui Sakano, Akira Oguri

AI总结:

本文提出适用于多能级量子点和磁性合金的费米液体理论,计算三体关联修正,揭示洛伦兹数偏离维德曼-弗兰兹定律的$T^2$依赖及对噪声的影响。

摘要:

我们提出了一个全面的费米液体描述,适用于热电输运和电流噪声,该描述可应用于多能级量子点(QD)和磁性合金(MA),且不要求电子-空穴或时间反演对称性。我们的低能输运公式基于具有$N$个离散杂质能级的安德森模型,在低能下渐近精确,直到关于温度$T$和偏压$eV$的幂展开中的次领头阶项。展开系数可以用费米液体参数表示,这些参数除了线性磁化率和杂质电子占据数$N_d^{}$之外,还包括相对于平衡基态定义的三体关联函数。我们将此公式应用于SU($N$)对称的量子点和磁性合金,并使用数值重整化群方法计算了$N=4$和$6$的关联函数。结果表明,在强库仑相互作用$U$下,三体关联在电子填充的广泛范围$1 \nlesssim N_d^{} \nlesssim N-1$内由单一参数决定,并且由于SU($N$)近藤效应,在$N_d^{}$的整数值处表现出平台结构。我们发现,对于量子点和磁性合金,洛伦兹数$L=\u03ba/(T \u03c3)$(定义为热导率$\u03ba$与电导率$\u03c3$之比)随着温度从$T=0$升高而偏离通用的维德曼-弗兰兹值$\u03c0^2/(3e^2)$,显示出$T^2$依赖性,其系数在远离半填充时依赖于三体关联。我们还展示了三体关联对非线性电流噪声和其他输运系数的作用。

英文摘要:

We present a comprehensive Fermi-liquid description for thermoelectric transport and current noise, applicable to multilevel quantum dots (QD) and magnetic alloys (MA) without electron-hole or time-reversal symmetry. Our formulation for the low-energy transport is based on an Anderson model with $N$ discrete impurity levels, and is asymptotically exact at low energies, up to the next-leading order terms in power expansions with respect to temperature $T$ and bias voltage $eV$. The expansion coefficients can be expressed in terms of the Fermi-liquid parameters, which include the three-body correlation functions defined with respect to the equilibrium ground state in addition to the linear susceptibilities and the occupation number $N_d^{}$ of impurity electrons. We apply this formulation to SU($N$) symmetric QD and MA, and calculate the correlation functions for $N=4$ and $6$, using the numerical renormalization group approach. The three-body correlations are shown to be determined by a single parameter over a wide range of electron fillings $1 \lesssim N_d^{} \lesssim N-1$ for strong Coulomb interactions $U$, and they also exhibit the plateau structures due to the SU($N$) Kondo effects at integer values of $N_d^{}$. We find that the Lorenz number $L=κ/(T σ)$ for QD and MA, defined as the ratio of the thermal conductivity $κ$ to the electrical conductivity $σ$, deviates from the universal Wiedemann-Franz value $π^2/(3e^2)$ as the temperature increases from $T=0$, showing the $T^2$ dependence, the coefficient for which depends on the three-body correlations away from half filling. We also demonstrate the role of three-body correlations on the nonlinear current noise and the other transport coefficients.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑