Surface Plasmon Polaritons in Strongly Correlated Media

Abstract

The “strange metal” phase, exhibited by certain types of graphene and high-Tc superconductors above the transition temperature, sits at the frontier of condensed matter physics. However, successfully describing the phase proves to be a difficult task, as it is characterized by strong correlations, making conventional methods fail. Hence there is a need of novel approaches, where an alternative method comes from high-energy physics in the form of the holographic principle. It states that the strongly coupled theory can be mapped to a dual, weakly coupled, gravitational theory in one dimension higher, making calculations go from impossible to feasible. Surface plasmon polaritons (SPPs) are a valuable tool in an experimentalists toolbox, as they can serve as a probe of their surroundings. They may therefore useful in the design of the experiments needed to answer the questions about the strange metal phase. In this thesis, we model SPPs propagating on a strange metal in a holographic setting. By numerically solving unwieldy differential equations in the dual gravitational theory, with boundary conditions specified by the SPP system, we are able to obtain some numerical dispersion relations for the plasmons, although more work is needed. The results suggest that magnetic effects, which normally are suppressed, might come into play when the material is strongly correlated.