Pulsed hysteresis loops on ferroelectric thin films

An alternative method to obtain hysteresis loops for ferroelectric thin films is described that overcomes the drawbacks of the classical methods. In this method, a pulsed signal, obtained by mixing a sinusoidal voltage of low frequency with a square voltage of variable period and width, is applied to a (Pb_0.76Ca_0.24)TiO₃ thin film. Electric field is applied to the sample for a short time and so, contribution of extra charges to the hysteresis loops is very small. The experimental loops measured only need a small compensation.