COMPRESSIBLE PHASE OF A DOUBLE-LAYER ELECTRON-SYSTEM WITH TOTAL LANDAU-LEVEL FILLING FACTOR-1/2

Following recent work of Halperin, Lee, and Read, and Kalmeyer and Zhang, a double-layer electron system with total Landau-level filling factor nu = 1/2 is mapped onto an equivalent system of fermions in zero average magnetic field interacting via a Chern-Simons gauge field. Within the random-phase approximation a new, low-lying, diffusive mode, not present in the nu = 1/2 single-layer system, is found. This mode leads to more singular low-energy scattering than appears in the single-layer system, and to an attractive pairing interaction between fermions in different layers which grows stronger as the layer spacing is decreased. The possible connection between this pairing interaction and the experimentally observed fractional quantum Hall effect in double-layer systems is discussed.