Capacitive interactions and Kondo effect tuning in double quantum impurity systems
Capacitive interactions and Kondo effect tuning in double quantum impurity systems
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DOI：
10.1103/physrevb.90.035119
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发表时间：
2014-04
影响因子：
3.7
通讯作者：
D. Ruiz-Tijerina;E. Vernek;S. Ulloa
中科院分区：
文献类型：
--
作者：
D. Ruiz-Tijerina;E. Vernek;S. Ulloa
本文研究了具有互电容作用的双量子杂质系统的相关输运态。这种系统可以通过双量子点布置或通过量子点和附近的量子点接触来实现，具有独立连接的金属端子组。在适当的条件下，每个点铅子系统内产生的多体自旋关联引起近藤效应。另外独立的近藤基态可以通过电容耦合进行修改，决定性地修改双量子杂质系统的基态。我们通过变分方法和数值重整化群技术分析了这个耦合系统。我们的研究结果揭示了强烈的依赖性的耦合系统的基态上的电子-空穴的不对称性的各个子系统，以及它们的杂交强度，以各自的水库。电容耦合产生的静电排斥作用使各个能级有效地向更高的能量移动，对“较浅”的子系统（更接近与费米能级共振）产生更强的影响，可能会将其推出近藤制度并显着改变系统的输运性质。研究发现，这需要的有效远程门控非线性地取决于电容耦合强度以及独立子系统级别。我们在这里提出的这种相互作用的分析应该是重要的，充分表征通过这种耦合系统的运输。
We present a study of the correlated transport regimes of a double quantum impurity system with mutual capacitive interactions. Such system can be implemented by a double quantum dot arrangement or by a quantum dot and nearby quantum point contact, with independently connected sets of metallic terminals. Many-body spin correlations arising within each dot-lead subsystem give rise to the Kondo effect under appropriate conditions. The otherwise independent Kondo ground states may be modified by the capacitive coupling, decisively modifying the ground state of the double quantum impurity system. We analyze this coupled system through variational methods and the numerical renormalization group technique. Our results reveal a strong dependence of the coupled system ground state on the electron-hole asymmetries of the individual subsystems, as well as on their hybridization strengths to the respective reservoirs. The electrostatic repulsion produced by the capacitive coupling produces an effective shift of the individual energy levels toward higher energies, with a stronger effect on the ``shallower'' subsystem (that closer to resonance with the Fermi level), potentially pushing it out of the Kondo regime and dramatically changing the transport properties of the system. The effective remote gating that this entails is found to depend nonlinearly on the capacitive coupling strength, as well as on the independent subsystem levels. The analysis we present here of this mutual interaction should be important to fully characterize transport through such coupled systems.