A new technique for measuring the critical magnetic field of cholesteric-nematic mixtures

✍ Scribed by Arthur L. Berman; Edward Gelerinter

• Publisher: Elsevier Science
• Year: 1975
• Tongue: English
• Weight: 277 KB
• Volume: 30
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(75)85518-7

✦ Synopsis

The criticzd magnetic field required for unwinhir& cholesteric-nematic mixtures is meanwed by t&i& advantage of the effects of the anisotropy of the dielectric tensor on the coupling of a microwave cavity. The results are used, elong v,ith literature values of the pitch, to obtain (fjz~/~Ix)"'. leakage current. The results of a typical run are shown in fig. 1. Here one sees a plot of the change in leakage bias cltrrent for a 200 Ci change in the magnetic field versus the applied magnetic field. In the region of H slightly less than H, one observes large changes in the bias currents. Above Hc the curve drops sharply. The mixture is unwound and ffie director is ptiallel to the magnetic field. Increasing the magnetic fieId no longer affects the alignment, or the dielectric constant, so that there is little change in the bias current.