P10: Thermoelectrics of quantum dots


Supervising Researchers


Project Description

The peculiar properties of solid state quantum materials make them promising candidates for the inter-conversion of heat and electrical energy in applications to cooling and waste heat recovery. A study within linear response theory showed that high thermoelectric efficiencies can be achieved in materials exhibiting sharp transport resonances (1),(2). Such resonances are realized, for example, in quantum dots (3). Due to their small size, quantum dots offer the possibility of converting heat into electrical energy on the nano- and meso-scales and they may also be easily manipulated and integrated within larger processing units. Transport resonances in quantum dots are strongly modified by correlations (Kondo-effect (4), charge-fluctuation effects (5)) with important consequences for their thermoelectric transport properties (6),(7).

In this project the numerical renormalization group (NRG) (8) and functional renormalization group (FRG) (9),(10) methods will be used to gain general insights into the effect of correlations on thermoelectric transport properties of quantum dots, possibly culminating in suggestions for novel systems with high thermoelectric efficiency. For this purpose models of multi-level quantum dots and a single-level quantum dot including a local phonon will be investigated. The latter can result in an effective attractive interaction on the quantum dot and should result in an
enhanced thermoelectric efficiency (11). Furthermore, the power output of quantum dot based thermoelectric elements
shall be better understood, and in particular its optimization for finite transport voltages and finite temperature gradients away from the linear response regime will be investigated (7), (12)-(14). This latter regime of steady-state non-equilibrium will be investigated with the aid of the FRG (15)-(17), (5). Depending on the progress in project P11 it may eventually also be possible to address this non-linear regime with a non-equilibrium NRG approach. Thermoelectric transport in periodically driven systems may also be addressed; see P14.

(1) G. D. Mahan and J. O. Sofo, Proc. Natl. Acad. Sci. USA 93, 7436 (1996)
(2) G. D. Mahan, B. Sales and J. Sharp, Phys. Today 50, 42 (1997)
(3) B. Kubala, J. König and J. Pekola, Phys. Rev. Lett. 100, 066801 (2008)
(4) T. A. Costi, Phys. Rev. Lett. 85, 1504 (2000)
(5) C. Karrasch, S. Andergassen, M. Pletyukhov, D. Schuricht, L. Borda, V. Meden and H. Schoeller,
Europhys. Lett.90, 30003 (2010)
(6) T.A. Costi and V. Zlatić, Phys. Rev. B 81, 235127 (2010)
(7) D. Kennes, D. Schuricht and V. Meden, Europhys. Lett. 102, 57003 (2013)
(8) R. Bulla, T. A. Costi and Th. Pruschke, Rev. Mod. Phys. 80, 395 (2008)
(9) W. Metzner, S. Salmhofer, C. Honerkamp, V. Meden and K. Schönhammer, Rev. Mod. Phys. 84, 299 (2012)
(10) C. Karrasch, R. Hedden, R. Peters, Th. Pruschke, K. Schönhammer and V. Meden,
J. Phys.: Condens. Matter 20, 345205 (2008)
(11) S. Andergassen, T. A. Costi and V. Zlatić, Phys. Rev. B 84, 241107(R) (2011)
(12) M. Leijnse, M. R. Wegewijs and K. Flensberg, Phys. Rev. B 82, 045412 (2010)
(13) C. Van den Broeck, Phys. Rev. Lett. 95, 190602 (2005)
(14) B. Sothmann and M. Büttiker, Europhys. Lett. 99, 27001 (2012)
(15) D. Kennes and V. Meden, Phys. Rev. B 87, 075130 (2013)
(16) S. Jakobs, V. Meden and H. Schoeller, Phys. Rev. Lett. 99, 150603 (2007)
(17) S. G. Jakobs, M. Pletyukhov and H. Schoeller, Phys. Rev. B 81, 195109 (2010)