Li ZhenHua, Wei JianHua, Zheng Xiao, Yan YiJing, Luo Hong-Gang
Beijing Computational Science Research Center, Beijing 100193, People's Republic of China. Department of Physics, Renmin University of China, Beijing 100872, People's Republic of China.
J Phys Condens Matter. 2017 May 4;29(17):175601. doi: 10.1088/1361-648X/aa6183. Epub 2017 Feb 20.
In the Kondo systems such as the magnetic impurity screened by the conduction electrons in a metal host, as well as the quantum dots connected by the leads, the low energy behaviors have universal dependence on the [Formula: see text] or [Formula: see text], where [Formula: see text] is the conventional Kondo temperature. However, it was shown that this scaling behavior is only valid at low-energy; this is called the Kondo scaling limit. Here we explore the extention of the scaling parameter range by introducing the corrected Kondo temperature T , which may depend on the temperature and bias, as well as the other external parameters. We define the corrected Kondo temperature by scaling the local density of states near the Fermi level, obtained by accurate hierarchy of equations of motion approach at finite temperature and finite bias, and thus obtain a phenomenological expression of the corrected Kondo temperature. By using the corrected Kondo temperature as a characteristic energy scale, the conductance of the quantum dot can be well scaled in a wide parameter range, even two orders beyond the conventional scaling parameter range. Our work indicates that the Kondo scaling, although dominated by the conventional Kondo temperature in the low-energy of the Kondo system, could be extended to a higher energy regime, which is useful for analyzing the physics of the Kondo transport in non-equilibrium or high temperature cases.
在近藤体系中,比如金属主体中被传导电子屏蔽的磁性杂质,以及由引线连接的量子点,其低能行为普遍依赖于[公式:见原文]或[公式:见原文],其中[公式:见原文]是传统的近藤温度。然而,研究表明这种标度行为仅在低能情况下有效;这被称为近藤标度极限。在此,我们通过引入修正的近藤温度(T)来探索标度参数范围的扩展,修正的近藤温度可能依赖于温度、偏压以及其他外部参数。我们通过对费米能级附近的态密度进行标度来定义修正的近藤温度,该态密度是通过在有限温度和有限偏压下精确的运动方程层级方法得到的,从而得到修正的近藤温度的唯象表达式。通过将修正的近藤温度用作特征能量标度,量子点的电导在很宽的参数范围内都能得到很好的标度,甚至超出传统标度参数范围两个数量级。我们的工作表明,近藤标度虽然在近藤体系的低能情况下由传统近藤温度主导,但可以扩展到更高的能量范围,这对于分析非平衡或高温情况下近藤输运的物理现象很有用。