Doctoral Dissertations

Date of Award

5-2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Physics

Major Professor

Jian Liu

Committee Members

Cristian D. Batista, David Mandrus, Norman Mannella

Abstract

Recent work on various quantum materials has led to fruitful result including unconventional magnetic states, topological properties, and exotic emergent phenomenon. High Tc superconductivity is one of the prominent properties discovered in quantum materials like strong correlated systems. Though the efforts on understanding this exotic behavior have lasted for years, the mechanism remains elusive owing to the many-body nature of the system and the research scope limitation within cuprates. Recent unravel of Jeff=1/2 state in the iridate square lattice offers alternative to study the complicated many body physics and potentially achieve high Tc superconductivity. In addition, the combination of electron correlation and strong spin-orbital coupling makes iridate a promising material to explore diverse exotic behaviors beyond cuprates.

This dissertation work utilizes the epitaxial heterostructure engineering to construct various Jeff=1/2 iridate thin films under different effective dimensionality to study both fundamental physics and explore new emergent phenomenon. Following a detailed survey of thermodynamic stability of Srn+1IrnO3n+1 thin films, the argon gas is found to be helpful in stabilizing Srn+1IrnO3n+1 under intermediate dimensionality. Epitaxial strain can be applied to stabilize chemical substituted SrIrO3 thin film where no bulk single crystal sample has been synthesized so far. Moreover, epitaxial strain is used to tune the correlation in a pseudospin-1/2 iridate superlattice within a Slater-Mott crossover regime. The physical properties of iridate superlattice is shown to be highly susceptible to structural modulation with observation that is rarely found in 3d transition metal oxides. The structural modulation on iridate thin film under 3D limit also successfully induces exotic transport properties which may originate from Berry curvature.

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