Resonant CarbonK-Edge Soft X-Ray Scattering from Lattice-Free Heliconical Molecular Ordering: Soft Dilative Elasticity of the Twist-Bend Liquid Crystal Phase

Chenhui Zhu, Michael R. Tuchband, Anthony Young, Min Shuai, Alyssa Scarbrough, David M. Walba, Joseph E. Maclennan, Cheng Wang, Alexander Hexemer, Noel A. Clark
2016 Physical Review Letters  
Resonant x-ray scattering shows that the bulk structure of the twist-bend liquid crystal phase, recently discovered in bent molecular dimers, has spatial periodicity without electron density modulation, indicating a lattice-free heliconical nematic precession of orientation that has helical glide symmetry. In situ study of the bulk helix texture for the dimer CB7CB shows an elastically-confined temperature-dependent minimum helix pitch, but a remarkable elastic softness of pitch in response to
more » ... ilative stresses. Scattering from the helix is not detectable in the higher temperature nematic phase.
doi:10.1103/physrevlett.116.147803 pmid:27104729 fatcat:v4i2sirql5dkhgdxmgkbxvn5pm