| Low Dimensional metals are the subjects of considerable current interest in the area of high magnetic field research. The reason being that the energy scales: μB, KT, Δ, (h*e*B)/(2*π*m) associated with these materials are all comparable, i.e. ∼20–45 T. These materials may be described simply as, single crystals, made of layers of organic or inorganic molecules, which comprise either (or both) one-dimensional chains or two-dimensional planes. In these directions, the electronic conductivity is relatively high and generally, the conductivity is several orders of magnitude lower in a third direction, which separates the most conducting quasi-two dimensional layers (Q2D). The resulting low dimensionality of such systems can lead to various instabilities and interactions at low temperatures, which cause these metals to undergo phase transitions to other ground states such as superconducting, semi-metallic, magnetic, or insulating phases. High magnetic fields play several important roles. First, for metallic systems the de Haas van Alphen (and Shubnikov de Haas) effects gives information concerning the nature of the Fermi surface of the materials. The behavior of the magnetoresistance (dependence of resistivity on magnetic field) can shed light on details of electronic transport in the low temperature ground states, and equally importantly, can detect any magnetic field induced phase transitions, which may occur. The primary thrust of this dissertation is the investigation of two Q2D systems, namely τ-(P-(S,S)-DMEDT-TTF)2(AuBr2)1(AuBr) 0.75 and λ-(BETS)2FeCl4 using high magnetic fields, low temperatures, induced pressure and the exploitation of anisotropy through the technique of Angular Dependent Magnetoresistance Oscillations (or AMRO). The fundamental information attained from these measurements are: (1) First observance of SdH oscillations in the τ-phase conductors. (2) A ground state that has yet to be identified in τ-phase conductors. (3) Inter-plane incoherent charge transport in τ-phase conductors. (4) Existence of high field superconductivity (SC) in the λ-phase superconductors. (5) Re-entrance to a normal state in the λ-phase superconductors (6) High field phase transitions in the λ-phase conductors at ambient and applied pressures.; The achieved results underscore the value of single crystal organic conductors as laboratories for low dimensional physics. |
