title: Ultrafast Polarization Switching in a Biaxial Molecular Ferroelectric Thin Film: [Hdabco]ClO4.
abstract: Molecular ferroelectrics are attracting much attention as valuable complements to conventional ceramic ferroelectrics owing to their solution processability and nontoxicity. Encouragingly, the recent discovery of a multiaxial molecular ferroelectric, tetraethylammonium perchlorate, is expected to be able to solve the problem that in the technologically relevant thin-film form uniaxial molecular ferroelectrics have been found to perform considerably more poorly than in bulk. However, it can show good polarization-electric field (P-E) hysteresis loops only at very low frequency, severely hampering practical applications such as ferroelectric random access memory. Here, we present a biaxial molecular ferroelectric thin film of [Hdabco]ClO4(dabco = 1,4-diazabicyclo[2.2.2]octane) (1), where a perfect ferroelectric hysteresis loop can be observed even at 10 kHz. It is the first example of a molecular ferroelectric thin film whose polarization can be switched at such a high frequency. Moreover, using piezoresponse force microscopy, we clearly observed the coexistence of 180° and non-180° ferroelectric domains and provided direct experimental proof that 180° ferroelectric switching and non-180° ferroelastic switching are both realized; that is, a flexible alteration of the polarization axis direction can occur in the thin film by applying an electric field. These results open a new avenue for applications of molecular ferroelectrics and will inspire further exploration of high-performance multiaxial molecular ferroelectric thin films.
authors.affiliation: Ordered Matter Science Research Center, Southeast University , Nanjing 211189, People's Republic of China.
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Tang
authors.affiliation: Ordered Matter Science Research Center, Southeast University , Nanjing 211189, People's Republic of China.
authors.forename: Wan-Ying
authors.initials: WY
authors.lastname: Zhang
authors.affiliation: Ordered Matter Science Research Center, Southeast University , Nanjing 211189, People's Republic of China.
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Li
authors.affiliation: Ordered Matter Science Research Center, Southeast University , Nanjing 211189, People's Republic of China.
authors.forename: Heng-Yun
authors.initials: HY
authors.lastname: Ye
authors.affiliation: Ordered Matter Science Research Center, Southeast University , Nanjing 211189, People's Republic of China.
authors.forename: Yu-Meng
authors.initials: YM
authors.lastname: You
authors.affiliation: Ordered Matter Science Research Center, Southeast University , Nanjing 211189, People's Republic of China.
authors.forename: Ren-Gen
authors.initials: RG
authors.lastname: Xiong