CHIRAL SURFACE-STATES IN THE BULK QUANTUM HALL-EFFECT

In layered samples which exhibit a bulk quantum Hall effect (QHE), a t wo-dimensional (2D) surface ''sheath'' of gapless excitations is expec ted. These excitations comprise a novel 2D chiral quantum liquid which should dominate the low temperature transport along the field (z axis ). For the integer QHE, we show that localization effects are complete ly absent in the ''sheath,'' giving a metallic z-axis conductivity. Fo r fractional filing nu = 1/3, the sheath is a 2D non-Fermi-liquid, wit h incoherent z-axis transport and sigma(zz) similar to T-3. Experiment al implications for the Bechgaard salts are discussed.