Unveiling the microscopic origin of the electronic smectic-nematic phase   transition in La1/3Ca2/3MnO3
  Electronic-liquid-crystal phases, in which part of the spatial symmetries are broken spontaneously, are considered to play a vital role in interpreting the structure-property relation in strongly-correlated materials. Although electronic-liquid-crystal phases have been inferred in studies of a wide range of materials, the nature of the transition between such phases has received little experimental attention. Here we report the direct observation of an electronic smectic-nematic phase transition in a doped manganite utilizing transmission electron microscopic techniques. We show that, in this case, the transition from the smectic to the nematic phase is driven by two mechanisms: the proliferation of dislocations and the development of mesoscale charge inhomogeneity. We observe the development of dislocation pairs within the commensurate smectic phase on approaching the transition (at 210 +/- 10 K) from below. Above the transition, the incommensurate nematic phase is accompanied by mesoscopic electronic phase separation. 
Jing Tao, Kai Sun, Weiguo Yin, S. J. Pennycook, J. M. Tranquada and   Yimei Zhu
cond-mat.str-el