MSE Faculty Candidate Seminar: “Engineering non-equilibrium structure and functionality in complex solids”

Unique macroscopic phenomena, such as high-temperature superconductivity and colossal magnetoresistance, emerge in many complex solids due to the interplay between their electronic, magnetic, and structural degrees of freedom. This interplay also results in properties that can be tuned by manipulating their atomic structure and symmetry. In this talk, Dr. Disa will discuss two complementary “non-equilibrium” pathways for inducing and influencing functionalities of complex oxides: atomic layer engineering and optical lattice control.

First, Dr. Disa will describe the control of electronic structure and transport properties of complex oxides through atomically-precise control of dimensionality and interfacial structure using molecular beam epitaxy. Specifically, he will show how picoscale engineering of atomic distortions is used to design the conductivity and the orbital configuration in rare-earth nickelates. Second, he will show that resonantly driving optical phonons with terahertz-frequency pulses allows one to engineer structural distortions dynamically, thus providing a pathway to control electronic and magnetic behavior on ultrafast time scales and even beyond statically possible. Dr. Disa will focus on a recent experiment demonstrating the formation of a metastable ferroelectric state in the common substrate material SrTiO3, which has a polarization that persists for hours after the optical excitation.

These approaches can work in tandem to enable the rational design of non-equilibrium functional properties in complex solids, which can be exploited for novel, high-speed optoelectronic and optomagnetic technologies.