Zac Ward – Oak Ridge National Laboratory

Titel: Disorder as an Order Parameter

Abstract: The way that materials behave can simply be thought of as a response to what the electrons in the material are doing. Controlling the atoms’ arrangement to one another in a crystal lattice changes where the electrons reside and how they interact with one another. If we can continuously control atomic compositions and structural relationships between the constituent elements, we can then manipulate functionality with unprecedented precision. In this presentation, I will describe our efforts to open previously inaccessible lattice symmetries and compositional phase spaces in strongly correlated quantum materials by means of light ion implantation and entropy-assisted synthesis. I will provide examples from our recent works that demonstrates how continuous control of symmetry opens new avenues to manipulate magnetic anisotropy and how compositional complexity can be used to design dynamic spin frustration by tailoring local degeneracies. We will close with a discussion of how shifting local variances in spin and exchange coupling types while maintaining position symmetries provides exciting opportunities for designing novel Griffiths phases or quantum many-body systems with tunable critical behaviors.

Bio: Zac Ward is a Senior Scientist in the Quantum Heterostructures Group at Oak Ridge National Laboratory. His research is directed at understanding and controlling electronic interactions in novel materials aimed at identifying transformative information and energy technologies of pressing economic and environmental need. Underpinning this effort is expertise in 1) single crystal film synthesis using pulsed laser deposition and light element ion implantation to tailor spin, charge, and orbital degrees of freedom; and 2) structural and functional characterization using labscale x-ray diffraction, magnetometry, transport characterization, and beamline-based x-ray spectroscopy and neutron reflectometry.