Condensed-Matter Physics & Materials Science Seminar

Complex oxides are promising materials for incorporation into next-generation, electronic devices due to their highly correlated d-electrons, which result in a wide variety of electronic and magnetic behavior, such as ferroelectricity, ferromagnetism and high-Tc superconductivity. These properties can often be changed through small variations in doping, strain or thickness, resulting in dramatic phase transitions. Oxide molecular beam epitaxy (MBE) is a growth technique that can produce coherently strained, atomically flat thin films, while also allowing for precise control of the stoichiometry. Absorption and photoelectron spectroscopies are valuable techniques for investigating the bulk and surface electronic structure of oxides. In addition, if the electric field polarization of the incoming photon can be manipulated, information on the magnetic structure can also be obtained. In this talk, I will discuss the growth and characterization of Co1-xFe2+xO4/MgO (001) thin films. These films were grown in a multi-chamber, ultrahigh vacuum (UHV) system, in which an analysis chamber, equipped with x-ray and ultraviolet photoelectron spectroscopies (XPS and UPS) and low energy electron diffraction (LEED), is attached to the growth chamber under UHV. The samples were further characterized at the National Synchrotron Light Source (NSLS), where x-ray absorption (XAS) and x-ray magnetic circular and linear dichroism (XMCD and XMLD) measurements were performed. The ability to grow high quality complex oxide thin films with MBE and characterize their electronic and magnetic structures with absorption and photoelectron spectroscopies makes the combination of these tools important in the investigation of these materials.