Dichroic optical and electrical properties of rhenium dichalcogenides layer compounds

Dichroic optical and electrical behaviors of layered ReX2 (X = S, Se) have been characterized using angular dependent polarized-absorption and resistivity measurements in the van der Waal plane. The polarized energy gaps of ReS2 and ReSe2 were analyzed from the polarized-absorption spectra with polarization angles from theta = 0 degrees (E parallel to b-axis) to theta = 90 degrees (E perpendicular to b-axis). The angular-dependent relationships of the polarized energy gaps of ReX2 were analyzed. Angular dependent resistivity measurements of ReX2 were carried out in the layer plane. The cutting edge of each sample was varied from theta = 0 degrees (11 b) to theta = 120 degrees with an increment of 10 degrees with respect to the layer crystal's b-axis. The angular dependency of the resistivities in the layered plane was analyzed. The experimental evidences of angular dependent in-plane resistivities and polarized energy gaps of ReX2 (X = S, Se) show that for ReX2 not only an optical dichroism but also an electrical dichroism in the van der Waal plane occurs. (C) 2007 Elsevier B.V. All rights reserved.