Angle resolved photoemission study of Fermi surfaces and single-particle excitations of quasi-low dimensional materials

Using angle resolved photoemission spectroscopy (ARPES) as the main experimental tool and the single particle Green's function as the main theoretical tool, materials of various degrees of low dimensionality and different ground states are studied. The underlying theme of this thesis is that of one dimensional physics, which includes charge density waves (CDW's) and the Luttinger liquid (LL). The LL is the prime example of a lattice non-Fermi liquid (non-FL) and CDW fluctuations also give non-FL behaviors. Non-FL physics is an emerging paradigm of condensed matter physics. It is thought by some researchers that one dimensional LL behavior is a key element in solving the high temperature superconductivity problem.; TiTe₂ is a quasi-2 dimensional (quasi-2D) Fermi liquid (FL) material very well suited for ARPES lineshape studies. I report ARPES spectra at 300 K which show an unusual behavior of a peak moving through the Fermi energy (E_F). I also report a good fit of the ARPES spectra at 25 K obtained by using a causal Green's function proposed by K. Matho. SmTe₃ is a quasi-2D CDW material. The near E_F ARPES spectra and intensity map reveal rich details of an anisotropic gap and imperfectly nested Fermi surface (FS) for a high temperature CDW. A simple model of imperfect nesting can be constructed from these data and predicts a CDW wavevector in very good agreement with the value known from electron diffraction. NaMo₆O₁₇ and KMo ₆O₁₇ are also quasi-2D CDW materials. The “hidden nesting” or “hidden 1 dimensionality” picture for the CDW is confirmed very well by our direct image of the FS.; K_0.3MoO₃, the so-called “blue bronze,” is a quasi-1 dimensional (quasi-1D) CDW material. Even in its metallic phase above the CDW transition temperature, its photoemission spectra show an anomalously weak intensity at E_F and no clear metallic Fermi edge. I compare predictions of an LL model and a CDW fluctuation model regarding these aspects, and find that the LL scenario explains them better. Despite the weak E_F intensity, the E_F intensity map shows a FS pattern in good agreement with the expected FS and the known CDW wavevector. Li_0.9Mo₆O₁₇ is a quasi-1D material, whose 24 K transition is incompatible with a CDW transition. I compare the 200 K ARPES lineshapes with the LL lineshapes calculated using the spin-independent Tomonaga-Luttinger model. I point out both strong similarities and some significant differences. (Abstract shortened by UMI.)...