Strong spin Seebeck effect in Kondo T-shaped double quantum dots

Abstract

We theoretically investigate the thermoelectric and spin thermoelectric properties of a T-shaped double quantum dot strongly coupled to two ferromagnetic leads, focusing on transport regime where the system exhibits the two-stage Kondo effect. We study the dependence of the (spin) Seebeck coefficient, the corresponding power factor and the figure of merit on temperature, leads' spin polarization and dot level position. We show that the thermal conductance fulfills a modified Wiedemann-Franz law. We also demonstrate that the spin thermopower is enhanced at temperatures corresponding to the second stage of Kondo screening. Very interestingly, the spin-thermoelectric response of the system is found to be highly sensitive to the spin polarization of the leads. In some cases spin polarization of the order of 1% is sufficient for a strong spin Seebeck effect to occur. This is explained as a consequence of the interplay between the two-stage Kondo effect and the exchange field induced in the double quantum dot. All calculations are performed with the aid of numerical renormalization group technique.

10 pages, 7 figures

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Cited by in corpus (5)

• Spin-Seebeck effect and spin polarization in a multiple quantum dot molecule
• Thermodynamics of energy, charge and spin currents in thermoelectric quantum-dot spin valve
• Enhancement of the thermoelectric efficiency in a T-shaped quantum dot system in the linear and nonlinear regimes
• Interplay of the Kondo effect with the induced pairing in electronic and caloric properties of T-shaped double quantum dots
• Thermoelectric properties of a quantum dot coupled to magnetic leads by Rashba spin-orbit interaction