Conductivity anisotropy helps to reveal the microscopic structure of a density wave at imperfect nesting

Superconductivity or metallic state may coexist with density wave ordering at imperfect nesting of the Fermi surface. In addition to the macroscopic spatial phase separation, there are, at least, two possible microscopic structures of such coexistence: (i) the soliton-wall phase and (ii) the ungapped Fermi-surface pockets. We show that the conductivity anisotropy allows to distinguish between these two microscopic density-wave structures. The results obtained may help to analyze the experimental observations in layered organic metals (TMTSF)$_{2}$PF$_{6}$, (TMTSF)$_{2}$ClO$_{4}$, $\alpha$-(BEDT-TTF)$_{2}$KHg(SCN)$_{4}$ and in other compounds.