Ergodicity breaking in stronium calcium titanate

Abstract

This work reports experimental results obtained from series of measurements of pyroelectric currents in samples of strontium calcium titanate (SCT) corresponding to contents of Ca of x = 0.002, x = 0.005 and x = 0.011. Sequences of zero field cooling (zfc), field heating (fh), field cooling (fc) and zero field heating (zfh) runs, under different applied electric fields, allowed the observation of the temperature and field dependence of the electric polarization under different initial conditions. The results show the existence of a weak non-ergodic regime in the compositions x = 0.005 and x = 0.011 and allow the tracing of the corresponding Almeida–Thouless line in the T –E diagram. For the three compositions investigated, a small zero field polarization is detected and interpreted as due to defect induced internal fields.