Resonant x-ray diffraction study of an unusually large phase coexistence in smectic liquid-crystal films

• Published in: Physical review letters Vol. 108; no. 3; p. 037801
• Main Authors: Pan, LiDong, Barois, P, Pindak, R, Liu, Z Q, McCoy, B K, Huang, C C
• Format: Journal Article
• Language: English
• Published: United States 19.01.2012
• ISSN: 1079-7114
• DOI: 10.1103/PhysRevLett.108.037801

The recent discovery of the new smectic-C(d6)(*) (SmC(d6)(*)) phase [S. Wang et al., Phys. Rev. Lett. 104, 027801 (2010)] also revealed the existence of a noisy region in the temperature window between the SmC(d6)(*) phase and the smectic-C(d4)(*) (SmC(d4)(*)) phase. Characterized by multiple resonant peaks spanning a wide region in Q(Z), the corresponding structure of this temperature window has been a mystery. In this Letter, through a careful resonant x-ray diffraction study and simulations of the diffraction spectra, we show that this region is in fact an unusually large coexistence region of the SmC(d6)(*) phase and the SmC(d4)(*) phase. The structure of the noisy region is found to be a heterogeneous mixture of local SmC(d6)(*) and SmC(d4)(*) orders on the sub-μm scale.