Strong enhancement of drag and dissipation at the weak- to strong- coupling phase transition in a bi-layer system at a total Landau level filling nu=1

摘要

We consider a bi-layer electronic system at a total Landau level fillingfactor nu =1, and focus on the transition from the regime of weak inter-layercoupling to that of the strongly coupled (1,1,1) phase (or ''quantum Hallferromagnet''). Making the assumption that in the transition region the systemis made of puddles of the (1,1,1) phase embedded in a bulk of the weaklycoupled state, we show that the transition is accompanied by a strong increasein longitudinal Coulomb drag, that reaches a maximum of approximately$h/2e^{2}$. In that regime the longitudinal drag is increased with decreasingtemperature.