General Features of the Primary Ferroics

All above means that the ferroics can be regarded as a general notation for the materials, where at T (so-called low-temperature phase) some reorientable physical quantities (order parameters) spontaneously appear. Latter order parameters can be of vector (spontaneous electric polarization, spontaneous magnetization) or tensor (second order tensor like spontaneous deformation or higher order tensors like elastic moduli and piezoelectric coefficients) nature. In low-temperature phase ferroics can usually split into domains, their switching being possible by the external fields. 

Above four main features of the ferroics can be summarized as follows (1) the existence of long range order for at least one macroscopic tensor property at r  

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