Si Wu
Published: 2010
Total Pages: 234
Get eBook
In the past three decades, quasi-low-dimensional organic materials haveattracted intense interests, both experimentally and theoretically. Due totheir reduced dimensionality and relatively low carrier concentration, many organic materials exhibit strong electron correlations and numerousinstabilities of the normal metallic state. The energy scales of suchinstabilities are often so low that the ground states can be changed by applyinga reasonably strong magnetic field. Therefore, magnetic field is an effectivetool for the study of quasi-low-dimensional organic materials. In this thesis, we will investigate two of these magnetic field related phenomena. In the first part, we will present our unified theory of angular magnetoresistanceoscillations observed in organic conductors. We will demonstrate that, in spite ofthe absence of Landau level quantization for open Fermi surfaces in a magnetic field, a new quantum effect - Bragg reflections of electrons moving in theextended Brillouin zone - determines unusual magnetic propertiesof these materials. We will demonstrate that, at commensurate directions of amagnetic field, the electron motion shows 1D 2 Ddimensional crossover and leads to strong resistivity minima. We will present ananalytic expression for interlayer resistivity, by both linear response formalism andsolving the Boltzmann kinetic equation in the extended Brillouin zone. In two limiting cases, our general solution reduces to the results previouslyobtained for the LMA effects and LNL oscillations. We demonstrate that our theoretical results are in good qualitative and quantitativeagreement with the existing measurements of resistivity in (TMTSF)