1. Coulomb Drag in a Strongly Correlated Double Layer 2D Electron System
Melinda Kellogg
James Eisenstein
Loren Pfeiffer
Ken West

2. Coulomb Drag V I e- e- e- e- Al0.9Ga0.1As nlayer = 5.3 x1010 cm-2
 ~ 106 cm2/V•s
GaAs
GaAs
180Å
99Å
180Å

3. Bilayer QHE Phase Diagram__ d l
Tunneling
Murphy et al., 1994

4. Temperature Dependence in Zero Field
Deviation from quadratic behavior -- no phonon peak

5. Above Tc, Pairing Fluctuations
Kim, Nayak, Demler & Das Sarma 2000
Bonesteel, McDonald,
Above Tc, Pairing Fluctuations
Ussishkin & Stern, 1998

6. Summary the drag resistivity at ntotal = 1.
We have discovered an enhancement in
the drag resistivity at ntotal = 1.
This enhancement appears well above the
bilayer QHE phase boundary.
This enhancement persists when the
layer densities are unbalanced.