Electrostatic Effects in Nanoscale Ferroelectrics

The behavior of nanoscale forms of matter, such as thin films or nanocrystal, is strongly influenced by the structure and behavior of their surfaces and interfaces. In nanoscale ferroelectrics, a surface charge arises as a consequence of the ferroelectric polarization itself, and this surface charge leads to an electrostatic instability – the so-called “polar catastrophe” – if it is not compensated. Here we show how the properties of ferroelectric materials at the nanoscale are intimately linked to the compensation mechanism that takes place at their surface. We also demonstrate how the structural and electronic properties of PbTiO₃, BiFeO₃ and KTaO₃ lead to a different compensation mechanism in each case, and we discuss how to harness the properties of these nanoscale materials for technological applications.