Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica, 8400 S C de Bariloche, Argentina.
J Phys Condens Matter. 2010 Oct 27;22(42):425602. doi: 10.1088/0953-8984/22/42/425602. Epub 2010 Oct 7.
We study non-equilibrium electron transport through a quantum impurity coupled to metallic leads using the equation of motion technique at finite temperature T. Assuming that the interactions are taking place solely in the impurity and focusing on the infinite Hubbard limit, we compute the out of equilibrium density of states and the differential conductance G(2)(T, V) in order to test several scaling laws. We find that G(2)(T, V)/G(2)(T, 0) is a universal function of both eV/T(K) and T/T(K), T(K) being the Kondo temperature. The effect of an in-plane magnetic field on the splitting of the zero bias anomaly in the differential conductance is also analyzed. For a Zeeman splitting Δ, the computed differential conductance peak splitting depends only on Δ/T(K), and for large fields approaches the value of 2Δ. Besides studying the traditional two leads setup, we also consider other configurations that mimic recent experiments, namely, an impurity embedded in a mesoscopic wire and the presence of a third weakly coupled lead. In these cases, a double peak structure of the Kondo resonance is clearly obtained in the differential conductance while the amplitude of the highest peak is shown to decrease as ln(eV/T(K)). Several features of these results are in qualitative agreement with recent experimental observations reported on quantum dots.
我们使用有限温度 T 下的运动方程技术研究了通过量子杂质与金属引线耦合的非平衡电子输运。假设相互作用仅发生在杂质中，并聚焦于无限 Hubbard 极限，我们计算了非平衡态态密度和微分电导 G(2)(T, V)，以测试几种标度律。我们发现，G(2)(T, V)/G(2)(T, 0)是 eV/T(K)和 T/T(K)的泛函，T(K)是科顿温度。我们还分析了平面内磁场对微分电导中零偏置异常劈裂的影响。对于塞曼分裂 Δ，计算出的微分电导峰值劈裂仅取决于 Δ/T(K)，并且对于大磁场，它趋近于 2Δ 的值。除了研究传统的双引线设置外，我们还考虑了其他模拟最近实验的配置，即杂质嵌入介观线中和存在第三个弱耦合引线。在这些情况下，在微分电导中清楚地获得了科顿共振的双峰结构，而最高峰值的幅度被证明随着 ln(eV/T(K))减小。这些结果的几个特征与最近关于量子点的实验观测在定性上是一致的。
