Coexistence of Mott and Peierls Instabilities in Quasi-One-Dimensional Organic Conductors

Abstract

The quasi-one-dimensional conductors have so far being studied for a long period (see Review [1]). Also these systems are now of interest for both theoreticians and experimentators (see Review [2]). This interest, on the one hand, is due to advances in synthesis of polyacetylene (PA) polydiacetylene (PDA), organic crystalline conductors based on6 molecular donors and acceptor of electron [2]. On the other hand, one-dimensional (1-d) conductors are nontrivial systems. Thus, 1-d metal is unstable to the transition in semi-conducting state. As a result, the simple 1-d metal with half-filled conduction band becomes the Mott semi-conductor or Peierls semi-conductor [1, 2]. The Peierls transition leads to dimerization - or bond length alternation - of the uniform 1-d lattice and semi-conducting energy gap is proportional to the dimerization amplitude. The Mott transition is a result of electron correlation and energy gap in the Mott semi-conductor vanishes with decreasing electron-electron interaction strength (see Refs. [1, 2] and references there-in). The semi-conductor of the Mott and Peierls type possesses some properties of interest. The Mott semi-conductors axe characterized by antiferromagnetic structures [2, 3]. In the Peierls semi-conductors the kink-type excitations are possible [4, 5].