Scanning tunneling microscopy of the organic conductors (TMTSF){sub 2}X (X = ClO{sub 4}{sup {minus}}, ReO{sub 4}{sup {minus}})
- Univ. of Minnesota, Minneapolis, MN (United States)
Scanning tunneling microscopy (STM) images of the (001) face (ab face) of the organic conductors (TMTSF){sub 2}X (TMTSF = tetramethyltetraselenafulvalene; X = ClO{sub 4}{sup {minus}}), ReO{sub 4}{sup {minus}} reflect the surface molecular corrugation and anisotropic stacking of TMTSF molecules along the [100] direction. The lattice constants of the (001) face determined from STM for (TMTSF){sub 2}ClO{sub 4} are a = 7.3 {plus_minus} 0.2 {Angstrom}, b = 7.8 {plus_minus} 0.2 {Angstrom}, and {gamma} = 69.5 {plus_minus} 2{degrees}, and for (TMTSF){sub 2}ReO{sub 4} they are a = 7.5 {plus_minus} 0.2 {Angstrom}, b = 8.1 {plus_minus} 0.2 {Angstrom}, and {gamma} = 70 {plus_minus} 2{degrees}, in excellent agreement with the known crystal structure. Height profile analysis of the tunneling current assigned to localized TMTSF electronic states is in agreement with the angle between the (001) face and the direction of the short axis of the TMTSF molecules. The STM images also are consistent with the high degree of electronic anisotropy of (TMTSF){sub 2}ClO{sub 4}, with a broad electronic state density associated with the pseudo-one-dimensional TMTSF stacks and a highly localized state density associated with Se-Se contacts between stacks along the [110] direction. The results are corroborated by STM of isomorphous (TMTSF){sub 2}ReO{sub 4} which exhibits negligible tunneling current associated with the Se-Se states, in agreement with the slightly larger Se-Se interstack distances in this compound. The lack of tunneling current in the interstack region of (TMTSF){sub 2}ReO{sub 4} signifies reduced electronic interaction transverse to the stacking direction, consistent with previously reported electronic properties of (TMTSF){sub 2}ReO{sub 4}. The results indicate that STM of a crystal plane can detect subtle differences in electronic structure that are responsible for bulk electronic properties in these materials. 39 refs., 5 figs., 1 tab.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 458830
- Journal Information:
- Journal of Physical Chemistry, Vol. 96, Issue 22; Other Information: PBD: 29 Oct 1992
- Country of Publication:
- United States
- Language:
- English
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