MAGNETORESISTANCE IN PULSED FIELDS, BAND-STRUCTURE CALCULATIONS AND CHARGE-DENSITY-WAVE INSTABILITY IN (TSET)(2)CL

Diffuse X-rays measurements assign the 26 K metal-semimetal transition in (TSeT)(2)Cl, where TSeT = tetraselenotetracene, to the stabilization of a 2k(F) = c*/4 charge-density wave ground state. Tight-binding extended Huckel band calculations suggest that 2k(F) yields to a partial nesting of the four conduction bands. Transverse magnetoresistance experiments performed up to 37 T confirm the previous observation of SdH oscillations. The 0(+) Landau level is evidenced for the first time.