Séminaire de groupe
Spindependent thermoelectric transport in HgTe/CdTe quantum wells 
Marine Guigou 
LPS Orsay/ParisSud 
jeudi 07 février 2013 , 14h00 
Salle de séminaire du groupe de Physique Statistique 
HgTe quantum wells are known to host, under a topological phase transition, the quantum spin Hall effect. The latter refers to the presence of metallic edge states moving in opposite direction for opposite spins. Recently, HgTe/CdTe quantum wells, among others topological insulators, have been proposed as good materials for thermoelectric conversion. The basic idea relies on the topological protection of the $1D$ edge states that prevents reduction of electrical transport in disordered systems. Their efficiency to convert heat into electricity is based on the dominance of the edge modes on transport [1,2]. During this presentation, I shall discuss about the thermoelectric properties of HgTe/CdTe quantum wells through the analysis of Seebeck and spin Nernst coefficents in a four terminal crossbar setup. As a lateral thermal gradient induces a longitudinal electric bias and a transverse spin current in such a system, each of them can be used as a probe of the topological regime as well as finite size effects of the quantum spin Hall insulator. Furthermore, I shall present a qualitative relative between effective mass of particles and magnitude of spin Nernst signal which allows to provide an explanation of the observed phenomena based on anomalous velocities and spindependent scattering off boudaries [3] . <br> [1] R. Takahashi and S. Murakami, Phys. Rev. B81, 161302 (2010). <br> [2] O.A. Tretiakov, A. Abanov, S. Murakami, and J. Sinova, Appl. Phys. Lett. 97, 073108 (2010). <br> [3] D.G. Rothe, E.M. Hankiewicz, B. Trauzettel, and M.G., Phys. Rev. B86, 165434 (2012). 
