In the last article, I have discussed about ferroelectricity and hysteriesis loop. Today we will discuss about the reason of hysteresis loop.

Ferroelectric crystals have regions with uniform polarization called ferroelectric domains.

A single crystal of ferroelectric material may contain number of domains in each of which the polarization and the crystal axes may have different directions. Domains are separated by interfaces called domain walls.

A single domain can be obtained by domain wall motion made possible by the application of electric field. A very strong field could lead to the reversal of the polarization in the domain and it is known as domain switching.

When electric field is applied, then the domain for which the polarization points along the direction of the applied field grow at the expense of other domains for which the polarization points in other directions.