Çetinkaya M C, Yildiz S, Özbek H, Losada-Pérez P, Leys J, Thoen J
Department of Physics, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey and Piri Reis University, 34970 Tuzla, Istanbul, Turkey.
Phys Rev E Stat Nonlin Soft Matter Phys. 2013 Oct;88(4):042502. doi: 10.1103/PhysRevE.88.042502. Epub 2013 Oct 7.
We report optical birefringence data by two different methods with high temperature resolution for octylcyanobiphenyl (8CB) near the smectic-A to nematic (Sm-A-N) phase transition temperature T(AN). Within the resolution of our experiments, we find that the Sm-A-N phase transition is continuous. For a possible discontinuity in the orientational order parameter S(T) at T(AN), we arrive at an upper limit of 0.0002, which is substantially smaller than other estimates in literature, but consistent with the value of 0.00008 derived from the upper limit of the latent heat from high-resolution adiabatic scanning calorimetry (ASC), which is itself consistent with the Halperin-Lubensky-Ma theory. The temperature derivative of the order parameter exhibits a power law divergence with a critical exponent that is consistent with the value α = 0.31 ± 0.03 for the specific heat capacity obtained by ASC.
我们通过两种不同方法报告了在近晶 - A 向向列相（Sm - A - N）转变温度 T(AN) 附近的高温分辨率下的辛基氰基联苯（8CB）的光学双折射数据。在我们实验的分辨率范围内，我们发现 Sm - A - N 相变是连续的。对于在 T(AN) 处取向序参量 S(T) 可能存在的不连续性，我们得出上限为 0.0002，这比文献中的其他估计值小得多，但与从高分辨率绝热量热法（ASC）的潜热上限导出的 0.00008 值一致，而该值本身与 Halperin - Lubensky - Ma 理论相符。序参量的温度导数表现出幂律发散，其临界指数与 ASC 获得的比热容的 α = 0.31 ± 0.03 值一致。
