QSCOUT: Quantum Scientific Computing Open User Testbed
Explore the source record for details and available documents.
Burch, Ashlyn Damaris↗
Engineering topics
McFarland, Brian
Publications and source records attributed to McFarland, Brian.
Electric Field Noise in Microfabricated Ion Traps with Varied Capacitor Types and Trap Materials.
Abstract not provided.
McFarland, Brian↗
Adhesion and Toxicity of Polymers Prepared Using Ionic Liquid Monomers
The focus of this research was to investigate possible applications of crosslinked polymers that could be prepared through free-radical polymerization of protic ionic liquid monomers. These monomers were synthesized through reactions of selected Bronsted acids and bases, and then polymerized with and without the aid of a free-radical initiator. It was discovered that these polymers had potential applications as adhesives, and bond strengths of various formulations were tested and compared with commercially available adhesives. Additionally, potential environmental toxicity of these polymers was investigated by performing zone of inhibition testing with select bacteria. It was determined that several of these polymers have comparable or superior bond strengths to other common adhesives, although monomer type and initiator concentration can impact these strengths. Toxicity was also dependent on these factors, with some formulations showing high toxicity and others showing few toxic effects.
36 MATERIALS SCIENCE↗
Observing Femtosecond Fragmentation Using Ultrafast X-ray-Induced Auger Spectra
Molecules often fragment after photoionization in the gas phase. Usually, this process can only be investigated spectroscopically as long as there exists electron correlation between the photofragments. Important parameters, like their kinetic energy after separation, cannot be investigated. We are reporting on a femtosecond time-resolved Auger electron spectroscopy study concerning the photofragmentation dynamics of thymine. We observe the appearance of clearly distinguishable signatures from thymine's neutral photofragment isocyanic acid. Furthermore, we observe a time-dependent shift of its spectrum, which we can attribute to the influence of the charged fragment on the Auger electron. This allows us to map our time-dependent dataset onto the fragmentation coordinate. The time dependence of the shift supports efficient transformation of the excess energy gained from photoionization into kinetic energy of the fragments. Our method is broadly applicable to the investigation of photofragmentation processes.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Hidden Interface Driven Exchange Coupling in Oxide Heterostructures
A variety of emergent phenomena have been enabled by interface engineering in complex oxides. The existence of an intrinsic interfacial layer has often been found at oxide heterointerfaces. However, the role of such an interlayerin controlling functionalities is not fully explored. Here, we report the control of the exchange bias (EB) in single-phase manganite thin films with nominallyuniform chemical composition across the interfaces. The sign of EB depends on the magnitude of the cooling field. A pinned layer, confirmed by polarized neutron reflectometry, provides the source of unidirectional anisotropy. The origin of the exchange bias coupling is discussed in terms of magnetic interactions between the interfacial ferromagnetically reduced layer and the bulk ferromagnetic region. The sign of EB is related to the frustration of antiferromagnetic coupling between the ferromagnetic region and the pinned layer. Our results shed new light on using oxide interfaces to design functional spintronic devices.
epitaxial thin films↗
Site-mixing effect on the XMCD spectrum in double perovskite Bi 2 FeMnO 6
We investigate magnetization in double perovskite multiferroic Bi 2 FeMnO 6 (BFMO) thin film using density functional theory (DFT) simulations, and X-ray magnetic circular dichroism (XMCD) measurements. The exchange interaction between Fe and Mn sites gives rise to a ferrimagnetic ordering in BFMO. When grown without structural defects, distinct XMCD signal is expected from this system. The site resolved magnetization, thus, can be extracted using XMCD sum rules. Although our theoretical calculations are consistent with this expectation for the ideal BFMO system, experimental measurements find evidence of anomalous peak for the L 2 and L 3 edges of XMCD signals, and thus, the XMCD sum rules are no longer valid. We theoretically explain this phenomenon by considering both tetragonal (near interface), and monoclinic (bulk) phases of BFMO system, with Fe and Mn ions interchanged between their respective sites. Such site-mixing between magnetic cations are commonly found during the synthesis process. Our DFT calculations of XMCD for site interchanged Fe and Mn ions in the bulk phase (monoclinic) of BFMO are in good agreement with experimental XMCD signal and reproduce the anomalous peak features at L 2 /L 3 edges.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗