Dr. Comes’ proposal entitled Metastable Oxides for High-Mobility and Spin-Orbit 2D Electronics has been chosen as one of 40 projects to be funded through the 2020 Air Force Young Investigator Program! This grant for $450,000 will begin in 2020 and support the group’s research in the use of hybrid molecular beam epitaxy to stabilize oxides that act as strong donors across interfaces and exhibit high spin-orbit coupling. Graduate student Suresh Thapa has already been hard at work developing these capabilities and now the group will be able to dive into the project. To learn more about the project, take a look at the Auburn news release.
Dr. Comes spent three great days in Lisbon, Portugal at the Fusion Oxide Thin Films Conference where he presented an invited talk on our group’s work studying the surfaces of SrTiO3 films by hybrid MBE using our in vacuo XPS. Ph.D. student Suresh Thapa is leading the work, along with contributions from Rajendra Paudel and Sydney Provence. In addition to some great talks and discussions, he was awarded the Emerging Young Investigator Award from the conference organizers. It was a nice honor to recognize the new research directions we’re able to pursue in FINO Lab at Auburn with our unique hybrid MBE+XPS capabilities.
Dr. Comes’ collaborative paper with Stony Brook University and the University of Virginia focusing on V1-xNbxO2 thin films has been published in Physical Review B. In this paper we look at the effect of alloy composition in these materials and show that niobium ions donate an electron to vanadium, reducing conductivity in films near x = 0.5. Using ultrafast THz spectroscopy and temperature-dependent transport we confirm this for thin films. At Auburn, we used our ion accelerator to perform Rutherford back scattering measurements that confirm the composition of these materials. Thanks to Tami Isaacs-Smith for performing the RBS measurements!
Congratulations go out to FINO Lab Ph.D. student Miles Blanchet, who won a fellowship through the Alabama EPSCOR Graduate Research Scholars Program! The fellowship will support his research on the synthesis and catalytic properties of oxide thin films and nanocomposites. We’re also happy to congratulate our collaborators on our NSF funded project, Alex Bredar and Prof. Byron Farnum. Alex also won the fellowship, meaning that we’ll be doubling the size of our team with additional grad students in the coming months. Watch out for more interdisciplinary science soon!
The FINO Lab will be hitting the road for a trip to Orlando to present our ongoing work at the American Ceramics Society Electronic Materials and Applications conference! Look for Miles Blanchet’s talk on Mn-based spinels from our ongoing NSF project on oxide films for hybrid catalysts and Suresh Thapa’s presentation on surface studies of SrTiO3 grown by hybrid molecular beam epitaxy. Both students will be presenting Thursday morning in the Complex Oxide and Chalcogenide Semiconductors symposium that Dr. Comes has organized. Alex Bredar from our collaborator Prof. Byron Farnum’s group will also be presenting on our collaborative work on CuGaO2 mesoporous films that is in press with ACS Applied Energy Materials. Looking forward to a great week!
Our collaborative paper on LaMnO3 (LMO)/SrTiO3 (STO) interfaces has been published in Advanced Materials Interfaces. This work, led by Dr. Tiffany Kaspar at Pacific Northwest National Lab, explores changes to Mn valence in LMO at the interface with STO, showing that Mn is partially reduced to a 2+ valence at the interface due to the polar discontinuity between STO and LMO. This has important implications for understanding the behavior of oxide spintronic materials, where manganese-based oxides are of considerable interest.
Our newest paper is out in Physical Review B, focusing on interfacial electronic behavior in SrTiO3-LaCrO3 superlattices. Dr. Comes synthesized these samples at PNNL and Prof. Chuck Fadley’s group at UC Davis performed synchrotron standing-wave x-ray photoelectron spectroscopy measurements to probe how the interfaces led to a built-in electric potential gradient across the layers of the sample. Prof. Fadley’s group pioneered the use of these measurements, which allowed us to vary our sensitivity to different interfaces within the superlattice. We produced record-breaking standing-wave effects, which is indicative of excellent sample quality and material design, and allowed us to very carefully measure the electronic band alignment in each layer of the material. Our results support our previous interpretation from a paper published in Advanced Materials Interfaces in 2016. We also showed unprecedented interfacial sensitivity using the technique by identifying the individual SrO-CrO2 and LaO-TiO2 interfaces within the superlattice. This emerging technique for superlattice characterization is opening new doors for how to study complex materials and we hope that this paper is an important new step in that direction!
Dr. Comes presented an invited talk at the Gordon Conference on Defects in Semiconductors at Colby-Sawyer College last week discussing the role that defects play at the LaFeO3-SrTiO3 interface and presenting some of the first results from the new FINO Lab MBE and XPS. It was a great crowd and lively discussion!
After some hard work by all of our graduate students and some valuable help from Randy Dellwo at RBD Instruments, we have our monochromatic XPS system attached to the MBE and are up and running!
Our collaborative project with Prof. Byron Farnum in the Auburn Chemistry department was awarded from the Solid State and Materials Chemistry program at NSF! Over this three year project, we’ll be looking at epitaxial spinel and perovskite thin films to understand their physical and chemical behaviors as catalysts and then integrating them into nanocomposites to serve as bifunctional catalysts for the oxygen evolution and oxygen reduction reactions for hydrogen fuel cells. Check out more here and watch for presentations at conferences soon!