Order-disorder phase transition in layered Cu1/2NbS2 observed by electrical resistivity measurements

The electrical resistivity parallel and perpendicular to the NbS2 layers was measured on single crystals of the ternary layered copper dichalcogenide Cu1/2NbS2 in the temperature range 1-300 K. At about 268 K the authors observe a 30% step in the otherwise linear temperature dependence of the resistivity both parallel and perpendicular to the layers exhibiting a hysteresis of 10 K in width. There are no significant changes of the electrical anisotropy and the Hall coefficient in the transition region. A model is proposed that explains these observations in terms of scattering of charge carriers induced by Cu disorder.