UC San Diego

This dissertation describes the characterization of complex electronic materials via infrared magneto- spectroscopy. It primarily focuses on the interplane electrodynamics of the high-transition-temperature cuprate superconductors, but is extended to include semiconductors and semimetals. Due to the complex interconnection between superconductivity and magnetism, the magnetic field provides an ideal method for tuning the phase coherence of the superconducting order parameter. One component of this work examines the low-frequency response of the cuprates in the vortex state and critically assesses several theoretical descriptions of the vortex lattice dynamics. A detailed sum rule analysis in magnetic field illuminates the role of phase coherence and kinetic energy change in the formation of the superconducting condensate. The magneto-optical data for a range of cuprates are then discussed in the context of recent magneto-oscillation measurements, addressing the plausibility of coherent antinodal quasiparticle pockets on the Fermi surface. Finally, an infrared study of the proposed topological insulator Bi2Se3 utilizes a novel experimental apparatus to uncover dramatic spectral weight redistribution and electron-phonon coupling in this highly thermoelectric material