CYCLOTRON-RESONANCE IN ORGANIC METAL ALPHA-(ET)(2)TLHG(SCN)(4)

Cyclotron resonance studies of the density-wave state of organic charg e-transfer salt alpha-(ET)(2)TIHg(SCN)(4). were done in the frequency range 50-100 GHz. Two strong resonances were observed, with the effect ive mass values equal to 1.3 and 0.5 m(0) respectively. Heavy mass is in a very good agreement with the Shubnikov-de Haas effect measurement s, while origin of the light one is not so clear. We attribute this li ght mass to the carriers on the Fermi-cylinder formed as a result of m agnetic breakdown in the nesting phase. The presence of two resonances shows that both nested and non-nested phases are present in the sampl e simultaniously.