engleski

Static and dynamic properties of low- temperature order in the one-dimensional semiconductor (NbSe4)3I

We investigated static and dynamic lattice properties in a quasi one-dimensional charge- ordered semiconductor (NbSe4)3I by using Raman, femtosecond pump-probe spectroscopy and x-ray diffraction. In addition to a well-documented pseudo-Jahn-Teller ferrodistortive structural transition at TC=274 K, where the displacements of Nb ions lead to ferroelectric (FE) in-chain polarization with opposite direction in adjacent chains, all methods suggest an additional lowering of symmetry at T*=160 K. Although antiferroelectric (AFE) phase is partially formed at TC, our results consistently point to an enhancement of the inter-chain order at T*, thus leading to AFE order-disorder transition, as supported by the earlier dielectric and structural studies.

pseudo Jahn-Teller ; pump-probe spectroscopy ; Raman spectroscopy ; XRD ; structural phase transition ; phonons

nije evidentirano