Emergent Properties in SrIrO₃ Heterostructures Grown by Metalorganic MBE

Transition metal complex oxides exhibit a host of intriguing properties for new technologies that can be tuned by the choice of ions from the 3<i>d</i>, 4<i>d</i>, and 5<i>d</i> blocks of the periodic table. This combination of properties, including superconductivity, ferromagnetism, and ferroelectricity, in a single class of materials offers rich opportunities for engineering of unusual combinations of behavior through the design of multi-layer thin films. Such heterostructures can exhibit topological phenomena due to interfacial coupling between distinct phases. Our work employs hybrid metal-organic MBE and <i>in situ </i>X-ray photoelectron spectroscopy (XPS) to explore oxide films that exhibit strong spin-orbit coupling and interfacial charge transfer. We have demonstrated the growth of hard-to-grow materials including SrNbO₃, SrIrO₃, and SrHfO₃ using metal-organic precursors and examined how interfacial phenomena can be tuned via charge transfer.<br/><br/>In this talk, I will discuss our work on SrIrO₃ heterostructures grown using an Ir(acac)₃ solid-source metal-organic precursor. We have synthesized epitaxial films under different thickness and strain conditions and examined the role that these play on the electronic transport and carrier dynamics. We show that the metallicity can be tuned via increasing compressive strain and employ time-domain THz spectroscopy to examine the origins of this behavior. Additionally, we have examined ways to tune the Fermi level in SrIrO₃ using SrNbO₃ as an n-type interfacial donor and SrCoO₃ as a ferromagnetic p-type interfacial acceptor. I will discuss how these interfaces change the transport behavior in SrIrO₃ through charge transfer using <i>in situ </i>XPS and <i>ex situ </i>X-ray absorbtion spectroscopy and scanning transmission electron microscopy. These new synthesis capabilities open routes to tuning of electronic structure in iridate films, which have been predicted to exhibit superconductivity in low-dimensional systems.