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arXiv · 0903.2685

Quantum phase transition and underscreened Kondo effect in electron transport through parallel double quantum dots

Guo-Hui Ding·Fei Ye·Bing Dong
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Abstract

We investigate electronic transport through parallel double quantum dot(DQD) system with strong on-site Coulomb interaction and capacitive interdot coupling. By applying numerical renormalization group(NRG) method, the ground state of the system and the transmission probability at zero temperature have been obtained. For a system of quantum dots with degenerate energy levels and small interdot tunnel coupling, the spin correlations between the DQDs is ferromagnetic, and the ground state of the system is a spin 1 triplet state. The linear conductance will reach the unitary limit ($2e^2/h$) due to the underscreened Kondo effect at low temperature. As the interdot tunnel coupling increases, there is a quantum phase transition from ferromagnetic to anti-ferromagnetic spin correlation in DQDs and the linear conductance is strongly suppressed.

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Guo-Hui Ding, Fei Ye, Bing Dong. 2009-06-01. Quantum phase transition and underscreened Kondo effect in electron transport through parallel double quantum dots. https://doi.org/10.1088/0953-8984%2F21%2F45%2F455303

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