Coulomb drag in high Landau levels

•von Oppen Felix1,2, Mirlin A.D.3,4 und Gornyi I.V.3
2Dept. of Cond. Matter Physics, Weizmann Inst. of Science, Rehovot, Israel
3Inst. f. Nanotechnologie, FZ Karlsruhe, 76021 Karlsruhe
4Inst. f. Theorie der Kond. Materie, Uni Karlsruhe, 76128 Karlsruhe
1Inst. f. Theor. Physik, FU Berlin, Arnimallee 14, 14195 Berlin

Coulomb drag between two parallel two-dimensional electron systems provides insight that is complementary to conventional transport measurements. Recent experiments [1] found several surprises in Coulomb drag in strong magnetic fields, in the limit of high Landau level filling factor, including negative drag and an anomalous temperature dependence. In this talk, we present a theory of Coulomb drag in high Landau levels which is perturbative in the interlayer interaction and treats disorder within the framework of the self-consistent Born approximation. We show that in the experimentally relevant ballistic regime, there are several contributions to Coulomb drag which differ parametrically but are numerically of comparable magnitude in typical experiments. One class of contributions is associated with the breaking of particle-hole symmetry by the Landau-level density of states, while another, more conventional, contribution arises from the breaking of this symmetry by the curvature of the electron dispersion. We show that the interplay of these contributions allows for a qualitative understanding of many features of the existing experiments.