of the top and bottom portions of the 'S' curve by vertical lines at the discontinuities gives the hysteresis loop of internal polarization due to an external electric field. Sliding ferroelectricity Sliding ferroelectricity is widely found but only in two-dimensional (2D) van der Waals stacked layers. The vertical electric polarization is switched by in-plane interlayer sliding. See also :Category:Ferroelectric materials Physics s Lists References Further reading External links Ferroelectric Materials at University of Cambridge Ferroelectric materials Electric and magnetic fields in matter Electrical phenomena Phases of matter