AVS 45th International Symposium
    Surface Science Division Thursday Sessions
       Session SS-ThP

Paper SS-ThP25
Surface Reconstruction and Charge Density Wave on ß-(BEDT-TTF)@sub 2@PF@sub 6@ Studied by Scanning Tunneling Microscopy

Thursday, November 5, 1998, 5:30 pm, Room Hall A

Session: Surface Science Division Poster Session
Presenter: M. Ishida, University of Tsukuba, Japan
Authors: M. Ishida, University of Tsukuba, Japan
K. Miyake, University of Tsukuba, Japan
K. Hata, University of Tsukuba, Japan
T. Mori, Tokyo Institute of Technology, Japan
H. Shigekawa, University of Tsukuba, Japan
Correspondent: Click to Email
ß-(BEDT-TTF)@sub 2@PF@sub 6@ is one of the quasi-one-dimensional organic conductors and is known to show metal-insulator transition at ~297 K with Charge Density Wave(CDW). STM/AFM study on this crystal revealed the characteristic properties of the molecular crystal surface for the first time. On the PF@sub 6@ surface, superstructure was formed by missing alternate molecular rows of PF@sub 6@. This is the first observation of the surface reconstruction of molecular crystal including a dractic change in the molecular arrangement.@footnote 1@ On the other hand, BEDT-TTF terminated surface induced molecular rearrangement with charge redistribution resulting in the symmetry breaking; formation of the two-fold periodicity in the direction perpendicular to the one-dimensional conductive axis. The origin of these structures could be explained comprehensively by the compensation mechanism of the incomplete charge transfer on the polar surface.@footnote 2@ Furthermore, STM measurement was performed from 80K to room temperature to observe the CDW phase directly. In the low temperature range up to 280 K, it was difficult to observe detailed surface structure because of low conductivity owing to the CDW gap. In the temperature range from 280 K, however, long range modulations were observed and we concluded that the modulations reflect the CDW phase. @FootnoteText@ @footnote 1@M. Ishida, K. Hata, T. Mori, and H. Shigekawa, Phys. Rev. B 55, 6773 (1997). @footnote 2@M. Tsukada and T. Hoshino, J. Phys. Soc. Jpn. 51, 2562 (1982).