This talk will consist of three parts: a brief introduction to Idaho National Laboratory and its work towards a clean energy future, followed by two projects developed using molecular beam epitaxy: The first one will deal with the synthesis of tensile strained quantum dots on the (111)A surface of GaSb, and the growth conditions that allowed a tunable emission wavelength in the mid-infrared. The third part of the talk will focus on the synthesis and characterization of epitaxial SmN thin films grown on the (100) surface of MgO. The properties of these films can be effectively tuned during growth by controlling the synthesis parameters. By carefully adjusting these parameters, we are able to drive SmN from an insulating ferromagnetic state to a ferromagnetic metallic state. Thin films samples are then compared to polycrystalline and powder samples of SmN. We discuss possible scenarios for the absence of superconductivity in these films and examine implications for the underlying pairing mechanism in this material. These findings open a new pathway for the epitaxial engineering of multifunctional materials, enabling the monolithic integration of diverse electronic phases, such as ferromagnetism and metallicity, without the lattice mismatch and strain typically associated with heteroepitaxial growth of dissimilar materials.
Speaker Bio:
Dr. Kevin D. Vallejo is from the Ciudad Juárez/El Paso border community, currently residing in Idaho Falls, Idaho. He obtained his Bachelor of Science degree in Physics from The University of Texas at El Paso, followed by his master’s and Ph.D. degrees in Materials Science from Boise State University. He is currently a materials scientist at Idaho National Laboratory, where he previously held a Rusell L. Heath distinguished postdoctoral position. Prior to his current appointment, Kevin served as a scientific advisor to the National Nuclear Security Administration. In addition to his day job, Kevin is interested in the aesthetic space where science, philosophy, and language meet.