Contribution of small closed orbits to magnetoresistance in quasi-two-dimensional conductors

Abstract

We find a striking peak structure in the magnetoresistance of the quasi-two-dimensional conductors $\ensuremath{\beta}\ensuremath{-}{(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\ensuremath{-}\mathrm{T}\mathrm{T}\mathrm{F})}_{2}{\mathrm{I}}_{3}$ and $\ensuremath{\alpha}\ensuremath{-}{(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\ensuremath{-}\mathrm{T}\mathrm{T}\mathrm{F})}_{2}{\mathrm{NH}}_{4}{\mathrm{Hg}(\mathrm{SCN})}_{4}$ for magnetic fields nearly parallel to the conducting plane. The peak structure can be ascribed to a Fermi-surface topological effect due to the small closed orbits on the side of the warped cylindrical Fermi surface. This effect provides a clue about how to evaluate the interlayer transfer integral.