title: Three relaxation processes from an electric-field-induced polar structure in a columnar liquid crystalline urea derivative.
abstract: We have studied the polarization relaxation process after removing an applied electric field in the columnar hexagonal phase of N,N'-bis(3,4,5-trihexadecyloxyphenyl)urea by means of second-harmonic generation (SHG), switching current, and texture observation. Transient SHG and current associated by sudden field change show polarization switching associated with a molecular reorientation of about a few ms depending on the field strength. Furthermore, the texture observation reveals a column undulation process during 10 s to 1 min. The size of the polar domains was estimated to be 160 molecules by analyzing the field dependence of the SHG signal intensity on the basis of an Ising model.
authors.affiliation: Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Okada
authors.forename: Shohei
authors.initials: S
authors.lastname: Matsumoto
authors.forename: Fumito
authors.initials: F
authors.lastname: Araoka
authors.forename: Masanao
authors.initials: M
authors.lastname: Goto
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Takanishi
authors.forename: Ken
authors.initials: K
authors.lastname: Ishikawa
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Nakahara
authors.forename: Keiki
authors.initials: K
authors.lastname: Kishikawa
authors.forename: Hideo
authors.initials: H
authors.lastname: Takezoe