In this paper, using a resonance-enhanced piezoresponse force microscopy approach
supported by density functional theory computer simulations, we have demonstrated
the ferroelectric switching in epitaxial GeTe films. It has been shown that in films with
thickness on the order of several nanometers reversible reorientation of polarization
occurs due to swapping of the shorter and longer Ge-Te bonds in the interior of the
material. It is also hinted that for ultra thin films consisting of just several atomic
layers weakly bonded to the substrate, ferroelectric switching may proceed through
exchange of Ge and Te planes within individual GeTe layers