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arXiv · 1611.03816

Spin filtering and thermopower in star coupled quantum dot devices

J. A. Andrade·Pablo S. Cornaglia
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Abstract

We analyze the linear thermoelectric transport properties of devices with three quantum dots in a star configuration. A central quantum dot is tunnel-coupled to source and drain electrodes and to two additional quantum dots. For a wide range of parameters, in the absence of an external magnetic field, the system is a singular Fermi liquid with a non-analytic behavior of the electric transport properties at low energies. The singular behavior is associated with the development of a ferromagnetic or an underscreened Kondo effect, depending on the parameter regime. A magnetic field drives the system into a regular Fermi liquid regime and leads to a large peak ($\sim k_B/|e|$) in the spin thermopower as a function of the temperature, and to a $\sim 100\%$ spin polarized current for a wide range of parameters due to interference effects. We find a qualitatively equivalent behavior for systems with a larger number of side coupled quantum dots, with the maximum value of the spin thermopower decreasing as the number of side-coupled quantum dots increases.

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J. A. Andrade, Pablo S. Cornaglia. 2016-11-11. Spin filtering and thermopower in star coupled quantum dot devices. https://doi.org/10.1103/physrevb.94.235112

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