Suppression of Stacking Order with Doping in 1T-TaS[sub.2−x]Se[sub.x]

In 1T-TaS[sub.2−x]Se[sub.x], the charge density wave (CDW) state features a star of David lattice that expands across layers as the system becomes commensurate upon cooling. The layers can also order along the c-axis, and different stacking orders have been proposed. Using neutron scattering on powder samples, we compared the stacking order previously observed in 1T-TaS[sub.2] when the system is doped with Se. While at low temperature, a 13c layer sequence stacking was observed in TaS[sub.2]; this type of ordering was not evident with doping. Doping with Se results in a metallic state in which the Mott transition is suppressed, which may be linked to the absence of layer stacking.