Date of Award

Spring 1-1-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Daniel S. Dessau

Second Advisor

Dmitry Reznik

Third Advisor

Gang Cao

Fourth Advisor

Rahul Nandkishore

Fifth Advisor

Josef Michl

Abstract

The macroscopic quantum phenomenology of superconductivity has attracted broad interest from both scientific research and applications. Many exotic physics found in the first high TC superconductor family cuprate remain unsolved even after 30 years of intense study. Angle-Resolved Photoemission Spectroscopy (ARPES) provides the direct probe to the major information of the electronic interactions, which plays the key role in these exotic physics including high TC superconductivity. ARPES is also the best tool to study the electronic structure in materials that potentially hold high TC superconductivity, providing insight for materials research and design.

In this thesis, we present the ARPES study of the cuprate high TC superconductor Pb doped Bi2Sr2CaCu2O8+δ, and potential high TC superconductors K doped p-terphenyl, and trilayer nickelate La4Ni3O10. For Pb doped Bi2212, our study focuses on the key part of the electronic interactions--the self-energies. With the development of a novel 2-dimensional analysis technique, we present the first quantitative extraction of the fully causal complex self-energies. The extracted information reveals a conversion of the diffusive strange-metal correlations into a coherent highly renormalized state at low temperature followed by the enhancement of the number of states for pairing. We then further show how this can lead to a strong positive feedback effect that can stabilize and strengthen superconducting pairing. In K doped p-terphenyl, we discover low energy spectral gaps that persist up to 120 K, consistent with potential Meissner effect signal from previous studies. Among a few potential origins for these gaps, we argue that the electron pairing scenario is most likely. For La4Ni3O10, we present the Fermiology and electron dynamics of this material, and they show certain similarities to the cuprate electronic structure, as well as a few unique features.

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