H. Mori et al., CRYSTAL-STRUCTURE AND PHYSICAL-PROPERTIES OF ALPHA-(BEDT-TTF)(2)MM'(SCN)(4) [M=RB,CS,M'=CO,ZN], Synthetic metals, 86(1-3), 1997, pp. 1789-1790
The metal-insulator transitions occur at 190K and 20K for (BEDT-TTF)(2
)MM'(SCN)(4) [M=Rb, M'=Co,Zn] and [M=Cs, M'=Co,Zn], respectively. The
former transition at 190K might originate from electron-correlation wi
th lattice modulation, suggested by the measurements of magnetic susce
ptibility and X-ray structure at low temperature. This transition temp
erature is elevated with applying pressure due to the increase of U/4t
.