Transport properties of N bSe3 crystals with nanometer-scale transverse dimensions

Abstract

A systematic study of the finite-size effects in transport properties of NbSe$_3$ crystals has been undertaken in crystals having room-temperature unit length resistance up to 10$^5~\Omega \mu$m. A substantial modification of the shape of the resistance vs. temperature curves, $R(T)$, is observed for the thinnest crystals. The measurements of the resistance and the Shapiro steps show that the effective cross-section area responsible for single-electron and CDW transport is substantially below a sample cross-section area defined by atomic force and scanning electron microscopy. A time evolution of the $R(T)$ is found. It is shown that the observed time evolution is similar to one resulted from breaking of the chains. Thus for thinnest samples, the contribution from a$^*$ and c-axis transport should be taken into account