Chiral Surface States in the Bulk Quantum Hall Effect

In layered samples which exhibit a bulk quantum Hall effect (QHE), a two-dimensional (2D) surface “sheath” of gapless excitations is expected. 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 completely absent in the “sheath,” giving a metallic $z$-axis conductivity. For fractional filling $\nu =1\mathrm{}/3$, the sheath is a 2D non-Fermi-liquid, with incoherent $z$-axis transport and ${\sigma }_{\mathrm{zz}}\sim T^3$. Experimental implications for the Bechgaard salts are discussed.