Ferroelectricity and antiferroelectricity in CuCrO2-type multiferroic semiconductors

Multiferroic semiconductors of the CuCrO₂ type are considered. These materials, in the presence of free charge carriers, allow for the existence of opposite domains (in the ferroelectric FE _d phase), along with ordinary 180° domains (in the FE phase). The magnetization phase transition in a chiral multiferroic, allowing for piezoelectric effects in an antiferromagnet with a layered triangular structure which result in an incommensurate (helicoidal) spin structure, is phenomenologically described. The behavior of the ferroelectric polarization in the considered phases is characterized. The antiferroelectric is considered a system of parallel layers alternating in chirality sign with oppositely directed polarization vectors. The possibility of antiferroelectric phase transition due to the specific features of the dipole-dipole interaction is discussed.