Controlling electronic and magnetic properties in ruthenate and iridate thin films and heterostructures.

Iridates and ruthenates display a wide range of electronic and magnetic states, including unconventional superconductivity, magnetism, Mott insulating behavior, and topological properties. The strong coupling between their structural (such as octahedral rotations and dimensionality) and electronic / magnetic degrees of freedom make thin films a powerful platform for manipulating the electronic properties of iridates and ruthenates. To achieve this control, we employ oxide molecular beam epitaxy (MBE) synthesis combined with in situ angle-resolved photoemission spectroscopy (ARPES) to synthesize epitaxially strained films or heterostructures of iridates and ruthenates, and directly investigate their electronic structure. We report our efforts in employing epitaxial strain to manipulate the Fermi surface topology and superconducting transition temperature of the unconventional superconductor Sr2RuO4. We also utilize epitaxial strain to convert its sister compound, Ca2RuO4, from an antiferromagnetic insulator into a ferromagnetic metal, and subsequently manipulate its magnetic anisotropy. Finally, we describe our recent efforts in employing interfacial engineering between SrIrO3 and SrRuO3, where we are able to induce charge transfer from SrIrO3 into SrRuO3, thereby shifting the Fermi level closer to the Dirac point in SrIrO3.