Ultrafast spectroscopy and control of correlated quantum materials

Abstract

In this thesis, I describe research completed during my Ph.D. on correlated condensed matter systems using ultrafast optics. I begin with a broad overview of this field, focusing specifically on the essential physics involved in ultrafast processes and how that physics may be utilized, in the sense of either spectroscopy or control, to understand correlated systems. I then give a pedagogical introduction to second harmonic generation, both in theory and in practice, before describing results from four projects I completed in my Ph.D.—(i) a technical project concerned with automating polarization rotation in second harmonic generation, (ii), a demonstration that second harmonic generation may be used to differentiate charge density wave domains with opposite planar chirality, (iii) our discovery of an ultrafast reorientation transition in the antiferromagnetic semiconductor CaMn₂Bi₂, and (iv) second harmonic generation evidence for an amplitude-mode electromagnon in CuBr₂. I conclude by reflecting on the progress achieved in correlated electron physics as a result of this work, and by giving my own perspective on the future of this field.