Two-dimensional organic conductor θ-(BEDT-TTF)2RbZn(SCN)4 and θ-(BEDT-TTF)2CsCo(SCN)4 were investigated by X-ray diffraction measurements. Both salts exhibit an isostructural crystal structure at room temperature (RT). However, the RbZn salt undergoes a metal-insulator transition associated with superlattice formation of 2c. The charge ordered state below TMI was observed by crystal structure analysis taking into account of the superlattice. This modulation of 2c has no relation to the topology of the calculated Fermi surface nesting vector at all. Below TMI, the systematic deformations of BEDT-TTF molecular shape indicated charge disproportionation between BEDT-TTFs possibly caused by the electron correlation effect. On the other hand, in the CsCo salt, another incommensurate lattice modulation was found under high pressure of IGPa. This incommensurate modulation vector of (2/3 0 0.29) is in agreement with the nesting vector of Fermi surface under high pressure. In this system, it seems that small change caused by chemical substitution can vary the electronic state from the charge ordered state to the CDW state.
|Journal||Journal De Physique. IV : JP|
|Publication status||Published - Nov 1 2002|
|Event||International Workshop on Electronic Crystals - ECRYS 2002 - Saint Flour, France|
Duration: Sep 2 2002 → Sep 7 2002
ASJC Scopus subject areas
- Physics and Astronomy(all)