Ferroelectricity in Organic Molecular Crystals

Reentrant ferroelectricity in liquid crystals.

The ferroelectric (Sm C*)-antiferroelectric (Sm C*A)-reentrant ferroelectric (re Sm C*) phase temperature sequence was observed for systems with competing synclinic-anticlinic interactions. The basic properties of this system are as follows: (i) the Sm C* phase is metastable in the temperature range of the Sm C*A; (ii) the helix handedness inverts at both Sm C*-Sm C*A and Sm C*A-re-Sm C* phase ...

Ferroelectricity in Simple Binary Crystals

The origin of ferroelectricity in doped binary crystals, Pb1−xGexTe, Cd1−xZnxTe, Zn1−xLixO, and Hf1−xZrxO2 is discussed, while no binary ferroelectrics have been reported except for two crystals, HCl and HBr. The ferroelectricity is induced only in doped crystals, which shows an importance of electronic modification in chemical bonds by dopants. The phenomenological and microscopic treatments a...

Molecular theory of proper ferroelectricity in bent-core liquid crystals.

Antiferro- and ferro-electric ordering has been discovered in orthogonal smectic phases composed of nonchiral bent-core molecules. These systems are the only proper fluid ferroelectrics confirmed experimentally so far. We consider a molecular theory of proper ferroelectric ordering in isotropic, nematic and smectic A phases and conclude that the delicate balance between the tendencies for local...

Excitons in Organic Molecular Crystals

Quantum ferroelectricity in charge-transfer complex crystals

Quantum phase transition achieved by fine tuning the continuous phase transition down to zero kelvin is a challenge for solid state science. Critical phenomena distinct from the effects of thermal fluctuations can materialize when the electronic, structural or magnetic long-range order is perturbed by quantum fluctuations between degenerate ground states. Here we have developed chemically pure ...