| Issue |
J. Phys. I France
Volume 4, Number 10, October 1994
|
|
|---|---|---|
| Page(s) | 1439 - 1450 | |
| DOI | https://doi.org/10.1051/jp1:1994198 | |
J. Phys. I France 4 (1994) 1439-1450
Comparison of the electronic structures of isostructural (BEDT-TTF) 3(HSO 4) 2 and [ Ni(dddt) 2] 3(HSO 4) 2 molecular metals
Marie-Liesse Doublet1, Enric Canadell1, Jean-Paul Pouget2 and Rimma P. Shibaeva31 Laboratoire de Chimie Théorique, Université de Paris-Sud, 91405 Orsay Cedex, France
2 Laboratoire de Physique des Solides, Université de Paris-Sud, 91405 Orsay Cedex, France
3 Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow District, Russia
(Received 19 May 1994, accepted in final form 7 July 1994)
Abstract
The isostructural charge transfer salts (BEDT-TTF)
3(HSO
4)
2 and
[ Ni(dddt)
2]
3(HSO
4)
2 are metallic at room temperature and exhibit metal to
insulator transitions at 130 K and 25 K, respectively. X-ray diffuse scattering measurements
for (BEDT-TTF)
3(HSO
4)
2 and tight-binding band structure calculations for both salts
suggest that these transitions are most likely due to slight structural modifications,
probably donor displacements, which suppress the semi-metallic overlap in these 3:2 salts.
Although the Fermi surface of (BEDT-TTF)
3(HSO
4)
2 is made of closed loops, our study
suggests that this salt has remarkable pseudo-1D properties. We show that even when they are
isostructural, the BEDT-TTF and Ni(dddt)
2 salts can be electronically quite different,
because the LUMO of the latter donor is not too far in energy from the HOMO. Consequently,
the LUMO of Ni(dddt)
2 can mix into the partially filled bands of their charge transfer
salts, which are based on the HOMO of the donor. This feature can change noticeably the
topology of the band structure and the Fermi surface. We show that this actually happens in
[ Ni(dddt)
2]
3(HSO
4)
2 and that it can be the clue to understand the differences in
physical properties of the (BEDT-TTF)
2(HSO
4)
2 and [ Ni(dddt)
2]
3(HSO
4),
salts.
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