According to HAUP measurements, two ferroelectric boracites, Fe3B7O13I and Cu3B7O13Cl, manifest peaks of a gyration component g11 at each Curie point. These phenomena are entirely unintelligible from the usual concepts of the origin of ferroelectricity. Besides, the electrogyration effects of both crystals and also quite different. As has already been determined boracite crystals exhibit characteristic features of being improper ferroelectric. A phenomenological theory of improper ferroelectricity developed by Kobayashi is applied to these anomalous phenomena, and qualitative interpretations are successfully obtained.
The urgent goal of the optical polarimetry of solids is simultaneous and accurate measurements of circular dichroism together with circular birefringence. Needless to say, measurements of circular phenomena are extremely difficult compared with those of linear ones. As for circular birefringence, 170 years elapsed since its discovery by Arago until the development of the HAUP method, by which the accurate measurements of the gyration tensor components of a solid became possible for the first time. Subsequent to appearance of the HAUP method, attempts to extend the HAUP theory to being applicable for measurements of circular dichroism of crystals were followed by several authors. However any applications to real crystal were not fully successful. We completed fresh the theory of the extended HAUP. This paper reports the extended HAUP measurement of both circular birefringence and dichroism of fresnoite Ba2Si2TiO8. It is clearly found that the circular dichroism abruptly appears at the transition temperature, where the crystal changes from the high temperature 4mm phase to the low temperature mm2 phase. It increases with decrease of temperature together with circular birefringence. This is the first proof that the HAUP method provides with sufficiently accurate data of circular dichroism of crystals. It is important to note that the circular dichroism affects only θ0, which is one of the salient parameter characterizing the HAUP method. It means that the HAUP is an exclusive method for measuring circular dichroism of crystals.
The goal of the polarimetry of electromagnetic solids is the thorough determinations of not only the linear and circular birefringences (LB an CB) but also the linear and circular dichroisms (LD and CD). Needless to say, measurements of circular phenomena are exceedingly more difficult than those of linear ones. For instance, the long period of 170 years elapsed from the discovery of CB by Arago in 1811 until the development of high accuracy universal polarimeter (HAUP) by Kobayashi in 1983, when the first perfect measurements of CB of solids became possible. Subsequent to the appearance of the HAUP method, attempts of extending HAUP theory to be applicable to CD measurements were followed by Moxon and Renshaw, and Dijkstra, Kremers, and Meekes by using Jones matrix calculus. However, their measurements to NiSO4 multiplied by 6H2O were not fully satisfactory. We completed afresh the theory of the extended HAUP and measured successfully LD of a high temperature superconductor Bi2Sr2CaCu2O8. An important fact was clarified; the extended HAUP theory indicates that CD can be obtained exclusively through accurate measurements of (theta) 0, a characteristic angle introduced in the original HAUP method. It means that there would be no ways for measuring CD of solids except for the HAUP method. Preliminary results of applying our theory to silver thiogallate are shown finally.
Optical activity was found in 1811 by Arago. However, optical activity of solids is extremely small and overwhelmed by existing birefringence, so it could not be measured until the high accuracy universal polarimeter (HAUP) was developed by us in 1983. The HAUP method enables us to measure optical activity and birefringence of any solids even belonging to monoclinic and triclinic systems. The principles of the HAUP and the more generalized one are given. The applications of the HAUP method to various kinds of solids, i.e., the elucidation of the origin of the incommensurate state of ferroelectrics, optical activities or monoclinic crystals, huge optical activity of high polymer sheet, and the first measurement of a protein, lysozyme, crystal are described. These applications illustrate that axial tensorial consideration provides otherwise inaccessible insight of previously unsolved problems. Therefore we stress the necessity of developing a new research field defined as chiral physics, where axial tensors play essential roles.
Conference Committee Involvement (3)
Complex Mediums VI: Light and Complexity
31 July 2005 | San Diego, California, United States
Complex Mediums V: Light and Complexity
4 August 2004 | Denver, Colorado, United States
Complex Mediums IV: Beyond Linear Isotropic Dielectrics
4 August 2003 | San Diego, California, United States
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