These monthly highlights, selected by MagLab Director Greg Boebinger, represent the most promising and cutting-edge research underway in the lab’s seven user facilities.
This work defines a new mechanism for radical-mediated catalysis of a protein substrate, and has broad implications for applied biocatalysis and for understanding oxidative protein modification during oxidative stress.
Characterization of Pine Pellet and Peanut Hull Pyrolysis Bio-Oils by Negative-Ion Electrospray Ionization FT&-ICR Mass Spectrometry
Pyrolysis of solid biomass, in this case pine pellets and peanut hulls, generates a hydrocarbon-rich liquid product (bio-oil) consisting of oily and aqueous phases. Here, each phase is characterized by negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) to yield unique chemical formulas for thousands of compounds.
Multiferroics — “Spintronics without heat” — coupled ferromagnetism and ferroelectricity can provide a new class of functional materials for needed applications including magnetic sensing, data storage and manipulation, high–frequency and high–power electronics, and energy savings.
Quantum Oscillations in a Candidate Topological Superconductor, a Copper-doped Topological Insulator: Cu1/4Bi2Se3
A superconducting ground state has been observed at T < 3.8 K in copper-doped Bi2Se3 single crystals. Topological superconductivity is predicted in this material, assuming the superconducting electrons follow the linear energy-momentum dispersion (Dirac-like) seen in graphene and other materials of current interest. However, this presumption had not yet been confirmed by quantum oscillation measurements.
Nematodes are the most abundant animal on earth, and they live in virtually every ecological niche on earth. Parasitic species have a significant health and economic impact through the infection of crops, domestic animals, and humans. Therefore, we are working to unravel the chemical language used by nematodes, with the ultimate goals of better understanding the role of small molecules in regulating behavior and of developing new approaches to control nematode parasites.
Researchers from the National High Magnetic Field Laboratory user program performed high-frequency (329 GHz) electron magnetic resonance (EMR) experiments to address questions of fundamental importance in catalysis 1) improving industrial production of ammonia and ammonia-derived fertilizers, and 2) understanding of the atmospheric nitrogen cycle.
MagLab engineers are building two cable-in-conduit superconducting coils for hybrid magnets, each with a resistive inner coil and a superconducting outer coil.
First direct evidence that filament fracture accompanies degradation of superconducting cables designed for the International Thermonuclear Experimental Reactor (ITER). The tokomak fusion reactor, now under construction in France, is an international collaboration crucial to future energy generation from nuclear fusion.
We report two-dimensional (2D) Dirac fermions and quantum magnetoresistance (MR) in Bi square nets of CaMnBi2 crystals.
Magnetic resonance imaging (MRI) of solid materials entails numerous problems from short longitudinal relaxation (T2) times to requiring strong gradients to attain high resolution images. A promising technique to address these issues is the Stray Field Imaging (STRAFI) method.
Powerful New Ionization Technique for Mass Spectroscopy That Avoids Fragmentation of Saturated Hydrocarbons
Here, we present a powerful new approach for the analysis of saturated hydrocarbon mixtures: atmospheric pressure laser- induced acoustic desorption chemical ionization (AP/LIAD-CI) with oxygen carrier/reagent gas.
Tilted magnetic fields were used to classify the broken symmetry states by their spin polarization. It was found that graphene turns into either a spin ferromagnet or some variety of density wave.
Molecules that exhibit slow magnetic relaxation upon removal from a polarizing magnetic field are referred to as single-molecule magnets (SMMs). SMMs receive considerable attention owing to their potential utility in applications such as spin-based information storage. In these systems, the slow relaxation normally arises from the action of an easy-axis magnetic anisotropy, quantified by a negative axial zero-field splitting parameter, D < 0, on a high-spin ground state. Two separate EPR studies carried out in the DC field facility by users from UC Berkeley (chemistry) have identified compounds that undergo slow relaxation, even though the relevant magnetic ions possess easy-plane-type anisotropy (i.e. D > 0).
Ferro-pnictide superconductors attracted immediate attention for potential applications due to their high superconducting transition temperatures (Tc up to 56 K) and high upper critical magnetic fields (Hc2 over 100 T). Unfortunately, much as in cuprates, grain boundaries (GBs) were found to obstruct their current carrying capability. This posed a serious technological problem because wires for magnets cannot be single crystals and, thus, inevitably contain grain boundaries. This work shows that low-temperature synthesis of the compound (Ba0.6K0.4)Fe2As2 (Ba-122) in the form of polycrystalline wire achieves a current density three times that of state-of-the-art Nb3Sn wires.
This experiment probes the nature of the 12/5 Fractional Quantum Hall state by using a hydraulic-driven rotator to tilt the two-dimensional system in a magnetic field.
Biomedical researchers have a unique tool to investigate a variety of living and excised specimen with the MagLab’s 21.1 T 900-MHz ultra-widebore (105-mm) vertical magnet. However, there are challenges to performing research in a high-field vertical magnet, which have been addressed by a NHMFL-led team of international scientists working to make very high field or ultra high field MRI more flexible. This team has constructed a tunable sliding ring transmit/receive volume coil for 900-MHz hydrogen MRI that provides the uniformity and sensitivity for high resolution and functional imaging of living samples while accommodating unique excised samples to improve characterization and throughput. This new design incorporates the apparatus necessary for maintaining animals in a vertical position while providing remote tuning and sample flexibility beyond most available coils.
Buckminster Fullerenes ("Buckyballs") have fascinated chemists since the original discovery of C60, leading to the 1996 Nobel Prize in Chemistry for Curl, Kroto and Smalley. Although fullerenes of various sizes have since been observed, the theoretically smallest fullerene, C28, has until now escaped detection, due to its high curvature and thus high reactivity.
Magnetic systems provide controllable “model” systems to study interacting many body quantum effects, relevant to poorly understood problems beyond the realm of magnetism. For example, disorder leads to Bose glass behavior, enabling study of the Bose-glass to BEC transition in quantum magnets — a key component to understanding the superconductor-to-insulator quantum phase transition. High magnetic fields drive Bose glasses into Bose-Einstein condensates.
Superfluorescence, historically, is the spontaneous emission of light from a collection of excited atoms. Scientists visiting the MagLab recently discovered superfluorescence for the first time in a solid material, by shining an extremely brief pulse of light on a layered semiconductor located in an intense magnetic field. In response, superfluorescent light of a different color was emitted thirty trillionths of a second later. Superfluorescence can be used to produce light of any desired color and could be enhanced to occur at room temperature and without magnetic fields. Superfluorescent devices would be powerful tools for optical communications.