Magnetic oscillations in a normal state of organic conductors: Many-body approach

We argue that magnetic and angular oscillations observed in quasi-one-dimensional (Q1D) organic conductors represent a new type of many-body phenomena. The physical nature of such effects as "magic angles" in (TMTSF)₂ClO₄, (TMTSF)₂PF₆, and (DMET-TSeF)₂ AuCl₂ as well as "rapid magnetic oscillations" in (TMTSF)₂ClO₄ is shown to be beyond the standard theory of metals. Below we discuss an explanation of these phenomena which utilizes unusual many-body effect - a change of an effective dimensionality of electron-electron ("e-e") interactions with changing both a magnitude and a direction of a magnetic field. We show that some exotic transport properties of a metallic state can be interpreted in terms of these dimensional crossovers. We also demonstrate that magnetic field dependence of "e-e" interactions has to break Fermi liquid description of quasiparticles at high magnetic fields, H ≥ 25 - 30 T. This leads to the appearance of strong forbidden oscillations of magnetic susceptibility, δχ/χ₀ ∼ 1-10, and magnetic moment, δM/M₀ ∼ 0.1. All of the above mentioned unique properties of a metallic phase in (TMTSF)₂X and (DMET-TSeF)AuCl₂ allow us to call it an anomalous metallic phase.