arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2201.04303cond-mat.str-el
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多通道Kondo模型在量子临界下的序参量

Order parameter for the multichannel Kondo model at quantum criticality

Ru Zheng, Rong-Qiang He, Zhong-Yi Lu

摘要:

多通道Kondo模型中两个或多个等效但独立的电子通道竞争屏蔽自旋为1/2的杂质,显示出杂质自旋的过度补偿,导致各种热力学和输运性质的非费米液体行为。然而,当沟道对称性被破坏时,杂质量子相变可以在零温度下发生。描述杂质量子相变的序参量的确定是非常困难的,因为它超出了传统的Landau-Ginzburg-Wilson理论。利用自然轨道重整化群方法,从电子通道中杂质与电子自旋关联的角度,研究了两通道和三通道Kondo模型.在这里,我们表明,通过引入自旋相关比作为序参量,我们可以表征杂质量子相变驱动的沟道不对称性。特别地,自旋相关比的普适临界指数$β$和相关长度的普适临界指数$ν$通过有限尺寸标度分析明确地确定,即分别对于两通道和三通道Kondo模型,分别为$β= 0.10(1), ν= 2.0(1)$和$β= 0.10(1), ν= 2.5(1)$.

英文摘要:

A multichannel Kondo model, where two or more equivalent but independent channels of electrons compete to screen a spin-1/2 impurity, shows overcompensation of the impurity spin, leading to the non-Fermi-liquid behavior in various thermodynamic and transport properties. However, when the channel symmetry is broken, an impurity quantum phase transition can occur at zero temperature. Identification of an order parameter describing the impurity quantum phase transition is very difficult since it is beyond the conventional Landau-Ginzburg-Wilson theory. By employing the natural orbitals renormalization group method, we study both two-channel and threechannel Kondo models, from the perspective of spin correlation between the impurity and electrons in electronic channels. Here we demonstrate that by introducing the spin-correlation ratio as an order parameter we can characterize impurity quantum phase transitions driven by channel asymmetry. In particular, the universal critical exponents $β$ of the spin-correlation ratio and $ν$ of the correlation length are explicitly determined by finite-sizescaling analysis, namely, $β= 0.10(1), ν= 2.0(1)$, and $β= 0.10(1), ν= 2.5(1)$ for the two-channel and three-channel Kondo models, respectively.

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