Anomalies of macroscopic quadrupole moment in an incommensurable phase of the crystal adjacent to the nonpolar and polar phases
Gladkii V.V. , Kallaev S.N., Kirikov V.A., Shuvalov L.A., Izrailenko A.N.
The anomalous spontaneous macroscopic quadrupole moment, which corresponds to the spatially modulated polarization, was determined and studied in the incommensurable phase of the (NH4)2BeF4 crystal. It is shown that this effect can be used to identify and investigate phases with such a structure.