Coherent vs incoherent interlayer transport in layered metals

Abstract

The magnetic-field, temperature, and angular dependence of the interlayer magnetoresistance of two different quasi-two-dimensional (2D) organic superconductors is reported. For $\kappa$-(BEDT-TTF)${}_2$I${}_3$ we find a well-resolved peak in the angle-dependent magnetoresistance at $\Theta =90^{\circ }$ (field parallel to the layers). This clear-cut proof for the coherent nature of the interlayer transport is absent for $\beta$''-(BEDT-TTF)${}_2$SF${}_5$CH${}_2$CF${}_2$SO${}_3$. This and the non-metallic behavior of the magnetoresistance suggest an incoherent quasiparticle motion for the latter 2D metal.

4 pages, 4 figures. Phys. Rev. B, in press