THE QUANTUM HALL-EFFECT IN ORGANIC METALS WITH BOTH QUASI-2-DIMENSIONAL AND QUASI-ONE-DIMENSIONAL FERMI-SURFACE COMPONENTS

The quantum Hall effect (QHE) is shown to be a natural property in hig h magnetic fields of any system possessing both quasi-two-dimensional and quasi-one-dimensional Fermi-surface components. Such Fermi surface s are known to occur in some organic charge-transfer salts (e.g. alpha -(BEDT-TTF)(2)MHg(SCN)(4) with M = K, Tl, NH4). Whilst the QHE in two- dimensional semiconductor systems such as heterostructures and MOSFETs relies on the existence of localized states at the edges of the Landa u levels, in organic metals the quasi-one-dimensional portion of the F ermi surface is shown to provide the necessary reservoir for pinning t he chemical potential between the completely filled and empty Landau l evels of the quasi-two-dimensional Fermi-surface section.