Cotton-Mouton Effect of Alkyl-and Alkoxy-Cyanobiphenyls in Isotropic Phase

概要

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The magnetic field induced birefringence 〓n has been measured for nCB (n=5-8) and n OCB (n=3, 5-9). Sufficiently above the clearing temperature T_c, all the materials investigated, except 7OCB, satisfy the relation〓n/H^2=λK_c/(T-T_c)over a wide temperature range of 20 ℃ or more. Here λ=633 nm is the wavelength used, T_c a temperature slightly lower than T_c, and K_c a constant. The anomaly observed in 7OCB is impurity sensitive. As the alkyl chain length increases, k_c drops appreciably; 3OCB has the largest value, k_c=2.98×10^<-10>℃cm^<-1>G^<-2>, while 7CB has the smallest value, k_c=0.99×10^<-10>. Near T_c, on the other hand, 〓n/H^2becomes larger than the above relation predicts. The two constants T_c-T_c and k_c are not enough to characterize the materials; (〓n/H^2)_<t=tc> is also an important factor. Among the materials investigated, 5OCB has the largest value of (〓n/H^2)_<t=tc>, namely 2.50×10^<-14>G^<-2>.
社団法人応用物理学会の論文
1979-11-05