Department of Physics, California Polytechnic State University, San Luis Obispo, California 93407, USA.
Phys Rev Lett. 2014 Apr 4;112(13):137801. doi: 10.1103/PhysRevLett.112.137801.
Critical behavior near the smectic A-C tricritical point is studied using renormalization group techniques. Critical fluctuations induce a singular softening of the smectic bulk modulus in the A phase. At the tricritical point, the quasi-long-range positional order of the smectic layers is destroyed. Despite this loss of order, dislocations remain bound so that smectic elasticity is retained but becomes anomalous, i.e., length scale dependent. The critically induced large layer fluctuations lead to negative thermal expansion of the layers in the A phase and may explain the origin of de Vries behavior. Experimental predictions are given for the temperature dependence of the smectic bulk modulus, x-ray structure factor, and layer spacing in the A phase.
使用重整化群技术研究了近向列 A-C 三临界点的临界行为。临界涨落导致向列体弹性模量在 A 相出现奇异软化。在三临界点，向列层的准长程位置序被破坏。尽管如此，位错仍然束缚着，从而保持了向列弹性，但变得反常，即与长度尺度有关。临界诱导的大层涨落导致 A 相中层的负热膨胀，并可能解释德弗里斯行为的起源。给出了向列体弹性模量、X 射线结构因子和 A 相中层间距随温度的实验预测。
