The Impact of Weak Magnetic Fields on Ferroelectric Crystals with Hydrogen Bonds

Abstract

The paper presents the review of works devoted to the effects of weak (with induction not exceeding 0.3 T) pulsed and a constant magnetic fields on the dielectric characteristics of hydrogen-containing ferroelectric crystals. By using the example of nominally pure triglycine sulfate and potassium dihydrophosphate, such weak magnetic fields were shown to cause a significant increase in the dielectric constant, coercive field, and a noticeable shift in the temperature of the ferroelectric phase transition. The interest shown in such studies is that the effects considered cannot be explained from the point of view of classical thermodynamics. For a long time, there was an opinion that magnetic fields with induction of less than 1 T in principle cannot affect the physical properties of diamagnetic materials in any way. However, experiments with numerous diamagnetic treated with weak magnetic fields showed the fallacy of such an opinion. The ferroelectric crystals referred to in the proposed work are also diamagnetic. Therefore, the apparatus of classical thermodynamics is not suitable for explaining the effect on the processing properties of weak magnetic fields. The effects of exposure are explained by the participation of protons of hydrogen bonds, which stabilize defective complexes, in electronic transitions responsible for the decay of these complexes and/or detachment of domain walls from them. An indirect confirmation of this explanation is the absence of the effect of magnetic fields (at least in the induction range 0.02-0.30 T) on single-crystal samples of barium titanate BaTiO3, an octahedral-type ferroelectric that has no hydrogen bonds in its structure.