Formation of a chiral surface state and interlayer conduction in a bulk quantum Hall system

Resistance measurements have been performed for the bulk quantum Hall system (TMTSF)₂AsF₆, where TMTSF denotes tetramethyltetraselenafulvalene. The interlayer resistance in the quantum Hall states is found to be independent of both temperature and quantum number at low temperatures. This fact can be ascribed to the formation of the chiral surface state, but the resistivity is much smaller than theoretical prediction. Sharp peaks in the interlayer resistance appear at transition fields between the adjacent quantum Hall states. The results suggest the presence of an intermediate state, which is not necessarily expected from standard theory.