Occurrence of hysteresis-like behavior of resistance of Sb2Te3 film in the dynamical measurement of heating-cooling cycle

Experimental observations of a peculiar behavior observed in the dynamical measurement of resistance of Sb2Te3 films in heating and cooling cycle at different heating and cooling rates are described. The film regained its original resistance, forming a closed loop, on the completion of the heating-cooling cycle which was reproducible for identical conditions of heating and cooling over many such cycles. The area enclosed by the loop was found to depend on (i) the thickness of the film, (ii) the heating rate, (iii) the maximum temperature to which film was heated and (iv) the cooling rate. The observations are explained on basis of model which considers the film to be a resultant of parallel resistances. The film's finite thermal conductivity gives rise to a temperature gradient along the thickness of the film, due to which the parallel combination of resistance changes with temperature in accordance with the temperature coefficient of resistance of the material. Difference in heating and cooling rates give different temperature gradient, which explains the observed hysteresis. This kind of dynamical measurement of resistance, exhibiting hysteresis could be quite useful in estimating the thermal conductivity of the material.