Orientational and fluctuation polarizations of langevin dipoles in a random electric field

The polarization and dielectric susceptibility of polar regions composed of Langevin microdipoles in a random electric field are considered. It is shown that the polarization of this system has orientational and fluctuation components in addition to the conventional phonon contribution. Both components diverge when the amplitude of the random field tends to zero but can be stabilized in finite internal fields. The orientational susceptibility does not depend on the external field if its amplitude is smaller than the amplitude of the random field and rapidly decreases in the opposite case. The field dependence of the fluctuation susceptibility exhibits a maximum. With an increase in the field, the fluctuation susceptibility quadratically increases as const + AE² in weak fields and decreases as E^?1/2 in strong fields. The equation of state takes the form P² ～ E in relatively strong fields (as compared to the internal field) and P ～ E in weak fields.