Polarized heat current generated by quantum pumping in two-dimensional topological insulators

Flavio Ronetti (1, 2, 3, 4) , Matteo Carrega (5) , Dario Ferraro (1, 4) , Jérôme Rech (1, 4) , Thibaut Jonckheere (1, 4) , Thierry Martin (1, 4) , Maura Sassetti (2, 3)

1 CPT - Centre de Physique Théorique - UMR 7332
2 UniGe - Università degli studi di Genova = University of Genoa
3 CNR SPIN
4 CPT - E6 Nanophysique
5 SNS - Scuola Normale Superiore di Pisa

We consider the transport properties of a two-dimensional topological insulator in a double quantum point contact geometry in the presence of a time-dependent external field. In the proposed setup an external gate is placed above a single constriction and it couples only with electrons belonging to the top edge. This asymmetric configuration and the presence of an ac signal allow for a quantum pumping mechanism, which, in turn, can generate finite heat and charge currents in an unbiased device configuration. A microscopic model for coupling with the external time-dependent gate potential is developed and the induced finite heat and charge currents are investigated. We demonstrate that in the noninteracting case, heat flow is associated with a single spin component, due to the helical nature of the edge states, and therefore a finite and polarized heat current is obtained in this configuration. The presence of e−e interchannel interactions strongly affects the current signal, lowering the degree of polarization of the system. Finally, we also show that separate heat and charge flows can be achieved, varying the amplitude of the external gate.

Domaines: Physique [physics]

Flavio Ronetti, Matteo Carrega, Dario Ferraro, Jérôme Rech, Thibaut Jonckheere, et al.. Polarized heat current generated by quantum pumping in two-dimensional topological insulators. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2017, 95 (11), pp.115412. ⟨10.1103/PhysRevB.95.115412⟩. ⟨hal-01498215⟩