Giant frictional drag in strongly interacting bilayers near filling factor one

E. Tutuc, R. Pillarisetty, M. Shayegan

Published 2008-08-28Version 1

We study the frictional drag in high mobility, strongly interacting GaAs bilayer hole systems in the vicinity of the filling factor $\nu=1$ quantum Hall state (QHS), at the same fillings where the bilayer resistivity displays a reentrant insulating phase. Our measurements reveal a very large longitudinal drag resistivity ($\rho^{D}_{xx}$) in this regime, exceeding 15 k$\Omega/\Box$ at filling factor $\nu=1.15$. $\rho^{D}_{xx}$ shows a weak temperature dependence and appears to saturate at a finite, large value at the lowest temperatures. Our observations are consistent with theoretical models positing a phase separation, e.g. puddles of $\nu=1$ QHS embedded in a different state, when the system makes a transition from the coherent $\nu=1$ QHS to the weakly coupled $\nu=2$ QHS.