18 August 2016

Best Research of 2015

A lot of great science happens at the National MagLab every year. Here’s a list of the best interdisciplinary research enabled by our world-record magnets in 2015.

Best of 2015

More than 1,600 scientists performed research at the National MagLab last year, taking on some of science's biggest questions about unique materials, the environment and health. Of the 478 reports submitted in 2015, these 36 were selected by the Science Council and lab director as the year’s best. Together, they represent the interdisciplinary ingenuity of the National MagLab, showcasing discoveries in condensed matter science, chemistry, life sciences and magnet technology across our seven user facilities. Some of the best-of’s are "firsts;" some landed in top-tier publications, including Science and Nature. All of them represent the power of high magnetic field research in making significant foundational discoveries.

Select a specific category to view below, or simply scroll down to read these highlights and follow links for more details.

Condensed Matter | Chemistry | Life Sciences | Magnets & Magnetic Materials

Condensed Matter Physics

2D Materials

Observation of the Quantum Hall Effect in Interface-Engineered Bi2Se3 Thin Films with Record Low Sheet Carrier Density and High Mobility

Salehi, M., Koirala, N., Moon, J. and Oh, S.
Published in Nano lett. (2015) 15 (12), 8245–8249

This report details the first observation of quantized hall conductance from a topological insulator surface state, namely Bi2Se3. This achievement was made possible by employing a novel buffer layer scheme composed of an In2Se3/(Bi0.5In0.5)2Se3 heterostructure to enable the necessary surface state carrier concentration and mobility combined with an insulating bulk so as to observe the hall resistance to quantize to h/e2 above 25T. Read report ....


Probing Ising superconductivity in atomically thin NbSe2 under high magnetic fields

Xi, X., Wang, Z., Zhao, W., Shan, J., Mak, K.F.; Park, J.-H.; Law, K. T.; Berger, H., Forro, L.
Published in Nature Phys. 12, 139 (2016).

2D crystals extracted from transition-metal dichalcogenides represent a new avenue for exploring collective quantum phenomena, such as superconductivity. This report describes the observation of superconducting monolayer (2D) NbSe2 with an-plane upper critical field Hc2 that far exceeds the conventional Pauli paramagnetic limit. The large enhancement of Hc2 is attributed to the presence of strong intrinsic spin-orbit interactions, which give rise to an unconventional Ising pair superconductivity. Read report ....


Fractional Quantum Hall Effect in a Fractal System

Wang, L.; Gao, Y.; Hone, J.; Taniguchi, T.; Watanabe, K.; Wen, B. and Dean, C.R.
Published in Science 350, 1231-1234 (2015).

This report describes the high magnetic field observation of anomalous quantum hall features arising in graphene/h-BN heterostructures with a Moiré super lattice pattern. The anomalous features in question are an additional series of hall quantized states that originate from a fractional Bloch index of the Moiré super lattice. The Bloch indices cluster around multiples of 1/3 and ½ indicative of strong electronic interactions which are as yet unpredicted by existing theory. Read report ....


Kondo/Heavy Fermion Systems

Quantum Criticality and its Anisotropy in the Quadrupole Ordered System PrV2Al20

Shimura, Y.; Nakatsuji, S.; Tsujimoto, M.; Zeng, B.; Zhang, Q. and Balicas, L.
Published in Physical Review B (Rapid Communication) 91, 241102(R) (2015).

Different symmetries are sometimes considered foundations for judging artistic beauty. An analogue approach is used in the design of new materials that have different symmetries associated with the microscopic crystalline-electric fields associated with their electronic orbitals. This work mapped the magnetic phase diagram of PrV2Al20, where the symmetry of the Pr orbitals lead to a low temperature ground state that possesses an electric quadrupole moment, but no magnetic moment. The discovery of a magnetic-field tuned quantum critical point arising from the quadrupole moments provides insight when contrasted with materials with different symmetries. Read report ....


Field-Induced Lattice Anisotropy in fcc UO2 from Magnetostriction to 90T

Gofryk, K.; Jaime, M.

This work demonstrates that UO2 is piezomagnetic, a rare state of matter in which the magnetostriction changes sign when the field changes sign, and requires particular low magnetic symmetry. The existence of piezomagnetism rules out two out of three of the competing theories for magnetic ordering in UO2 and selects one. The magnetic structure of UO2 remains a puzzle to this day. It combines complex non-collinear ordering with a multiply degenerate Jahn-Teller distortion that freezes and contributes to the ordering. The magnetic effects, particularly the dynamic Jahn-Teller distortions are intimately tied to the high-temperature thermal conductivity of this system, which is important for applications. Read report ....


Magnetism and Magnetic Materials

Magnetometry of the Candidate Kitaev Honeycomb Magnet α-RuCl3

Singleton, J.; Zapf, V.; Williams, S.C.; Haghighirad, A.A.; Johnson, R.D. and Coldea, R.
Published in Phys. Rev. B92, 235119.

The layered honeycomb material α-RuCl3 contains spin-orbit entangled j=1/2 magnetic moments that order antiferromagnetically below 13K. Applying a magnetic field parallel to the honeycomb planes induces a phase transition around 8T, with higher fields leading to a saturation. In a magnetic field applied perpendicular to the honeycomb planes, no phase transition is observed. The magnetic interactions are therefore strongly anisotropic and potentially of Kitaev form that could lead to anyon physics. The suggested zig-zag magnetic order is thus robust for fields perpendicular to the honeycomb planes, but is easily disturbed by a field parallel to the planes. Read report ....


Giant Suppression of Phononic Heat Transport in a Quantum Magnet BiCu2PO6

Jeon, B.-G.; Koteswararao, B.; Park, C.B.; Shu, G.J.; Riggs, S.C.; Moon, E.G.; Chung, S.B.; Chou, F.C. and Kim, K.H.

BiCu2PO6 is a quantum magnet and a frustrated ladder system. A remarkable two order of magnitude suppression of the thermal conductivity is observed as 30 T is applied. This is due to the partial closing of a spin gap, which allows phonons to resonantly scatter off magnetic excitations across the gap. Read report ....


Ferroelectricity in Metal Organic System at a Spin-State Transition

Chikara, S.; Singleton, J.; Lin, S.; Batista, C. ; Smythe, N. and Zapf, V.S.

A strong spin-lattice coupling is observed in Mn tris(1-(2-azolyl)-2-azabuten-4-yl)amine, where at 47K, the Mn ion undergoes a spin crossover transition from high-temperature high-spin (S=2) to low-temperature low-spin (S=0). A magnetic field can stabilize the high-spin state below the spin crossover transition temperature. Since the high-spin state has an electric polarization, a magnetic field can therefore induce an electric polarization, with potential ferroelectric behavior. Pulsed field experiments demonstrate a field induced electric polarization, indicating potential multiferroic behavior in a metal-organic compound. Read report ....


Enhancing Coherence in Molecular Spin Qubits via Atomic Clock Transitions

Komijani, D.; Shiddiq, M.; Duan Y.; Gaito-Arino A.; Coronado E. and Hill, S.
Published in Nature 531, 348 (2016).

This work demonstrates striking improvement in the performance of certain metal-organic molecules as potential building blocks for information storage in future quantum computers. Optimizing the strength of an applied magnetic field is shown to greatly reduce the rate at which the molecule’s spin loses coherence due to interaction with its environment, allowing the molecules to be packed closer together, an important benefit for quantum computing applications. Read report ....


Other Condensed Matter

Exciton Diamagnetic Shifts and Valley Zeeman Effects in Monolayer WS2 & MoS2 to 65T

Komijani, D.; Shiddiq, M.; Duan Y.; Gaito-Arino A.; Coronado E. and Hill, S.Stier, A.V. and Crooker, S.A.; McCreary, K.M.; Jonker, B.J. and Kono, J.
Published in Nature Commun. 7, 10643 (2016).

Transition metal disulphides and deselenides have electronic similarities to grapheme, except that spin-orbit interactions in atomically-thin samples lead to the opening of a massive gap at the Dirac points, giving rise to what are referred to as valleys. By symmetry, there are two degenerate valleys, but each is expected to have different pseudospin quantum numbers. Here, the authors for the first time demonstrate optically the existence of a valley Zeeman splitting using circularly polarized light, providing direct experimental evidence for the existence of valley quantum numbers. Read report ....


Quantum Transport of Two-Species Dirac Fermions in Dual-Gated Three-Dimensional Topological Insulators

Xu, Y.; Miotkowski, I. and Chen, Y.P.
Published in Nature Commun. 7, 11434 (2016).

Topological insulators have been found to exhibit a single topologically protected Dirac cone on their surface. Here, the authors have fabricated a thin device made from BiSbTeSe2 in which gating can be used to tune two independent Dirac cones on the top and bottom surfaces. The ability to tune these states independently leads to the possibility of a new type of functionality, such as that arising from the formation of a broken symmetry or excitonic insulator state. Read report ....


Evidence for the Chiral Anomaly in a Dirac Semimetal

Ong, N.P.; Xiong, J.; Kushwaha, S.K.; Liang, T.; Krizan, J.W.; Hirschberger, M.; Wang, W. and Cava, R.J.
Published in Science v350 413-416 (2015).

In this careful study of a Dirac semimetal, Ong et al have verified a prediction that a chiral anomaly can be supported in a 3D metal. Read report ....



Wigner solid of quasiholes of the υ = 1/2 fractional quantum Hall effect state

Hatke, A.T., Engel, L.W, Liu, Y., Shayegan, M., Pfeiffer, L.N., West, K.W., and Baldwin K.W.
Published in Nature Commun. 6, 7071 (2015).

A Wigner solid is the crystalline phase of electrons first predicted by Eugene Wigner in the 1930s; electrons moving in a very clean system will crystallize due to their mutual repulsion if the electron density is less than a critical value. Here, Wigner solidification has been observed for the first time in quasiholes associated with the ½ filling factor fractional quantum Hall state of a wide GaAs quantum well, showing that the same physics obtains with any charged fermion-like quasiparticle in a clean system. The solidification was observed using microwave (GHz) spectroscopy, and demanded an exceptionally pure GaAs-(Ga,Al)As quantum well with gate-controlled carrier density, plus mK temperatures and high magnetic fields. Read report ....


Quantum Oscillations in an Interfacial 2D Electron Gas

Zhang, Bingpo; Lu, Ping; Liu, Henan; Jiao, Lin; Ye, Zhenyu; Jaime, Marcelo; Balakirev, Fedor F.; Yuan, Huiqiu; Wu, Huizhen; Pan, Wei; and Zhang, Yong
Published in Nano Lett. 15, 4381 (2015).

In contrast to conventional topological insulators, in which the surface states are protected by time-reversal symmetry, in topological crystalline insulators (TCIs) the topological nature of electron structures arises from the crystalline symmetries. The search for TCIs is a veritable hotbed of theoretical and experimental activity, promising to generate much excitement for years to come. This report describes the first likely instance of a TCI in a novel type of a heterostructure. The observation of the Dirac fermion nature of a two-dimensional electron gas at the interface was only made possible with magnetic fields up to 60 T. Such heterostuctures are eminently suitable for improvement, such as gating, to allow for tests of theory and potential applications of TCIs. Read report ....


Basic Superconductivity

Quantum oscillations suggest hidden quantum phase transition in the cuprate superconductor Pr2CuO4±δ

Breznay, N.P.; Hayes, I.M.; Helm, T.; Analytis J.G.; Krockenberger, Y.; Yamamoto, H.; Modic, K. and McDonald, R.D.
Published in arXiv arXiv:1510.04268 (2015)

The specific problem of the electron-doped systems is their sensitivity to chemical doping and oxygen stoichiometry. The report demonstrates that MBE grown films are a new platform for studying the Fermi surface of cuprates. Using high quality thin films of Pr2CuO4±δ, superconductivity was tuned without Ce substitution for Pr. The observed magnetic quantum oscillations are consistent with the presence of small hole-like Fermi surface pockets. Read report ....


Contactless Measurements of Quantum Oscillations in the Cuprate Superconductor HgBa2CuO4+δ

Chan, M.K.; McDonald, R.D.; Harrison, N. and Greven, M.

Experiments performed with the 65T short pulse and 100T magnet at the Pulsed Field Facility in Los Alamos have shown that Hg1201 exhibits only a single small-frequency Shubnikov de-Haas oscillatory component without signatures of magnetic breakdown tunneling to additional orbits. Thereby, it is demonstrated that a small Fermi pocket is a universal feature common to all cuprates. (The quantitative interpretation of these results in terms of a biaxial charge-density-wave order within each CuO2 plane is hardly correct in the view that the specific heat measurements in Hg1201 (Kemper) reveal the presence of the small normal electronic contribution at low temperatures in the superconducting phase). Read report ....


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Environmental Chemistry

Unprecedented Insights into the Chemical Complexity of Coal Tar from Comprehensive Two-Dimensional Gas Chromatography Mass Spectrometry and Direct Infusion Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Koolen, H.H.F.; Swarthout, R.F.; Nelson, R.K.; Chen, H.; Krajewski, L.C. ; Aeppli, C.; McKenna, A.M.; Rodgers, R.P. and Reddy, C.M.
Published in Energy Fuels 25, 641-648 (2015).

Coal tar and its distilled products (e.g., creosote) are commonly applied wood preservatives and asphalt sealants that have been identified as significant sources of polycyclic aromatic hydrocarbons (PAHs) to the environment. Through a complementary approach with comprehensive two-dimensional gas chromatography (GC × GC) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), the authors analyzed residues suspected to be coal tar or creosote collected from beaches along coastal Texas in 2014. Atmospheric pressure photoionization (APPI) FT-ICR MS revealed ~14,000 mass spectral peaks between 150 and 900 Da, mainly aromatics and heterocycles with up to two nitrogen or three oxygen atoms per molecule. On the basis of a comparison of the FT-ICR MS data to the Boduszynski continuum, the authors confirmed that these samples were residues of a whole coal tar and not a distillate cut point such as creosote. Read report ....


Longitudinal Shifts in Dissolved Organic Matter Chemogeography and Chemodiversity within Headwater Streams: A River Continuum Reprise

Mosher, J.J.; Kaplan, L.A.; Podgorski, D.C.; McKenna, A.M.; Marshall, A.G.
Published in Biogeochemistry 124, 371-385 (2015).

Researchers tested a long-standing hypothesis within river ecology, predicted by the River Continuum Concept, that dissolved organic matter (DOM) diversity decreases with stream order. The authors measured DOM molecular composition across three stream orders in the headwaters of well-characterized forested catchments with ultrahigh-resolution mass spectrometry to assess DOM chemogeography and chemodiversity over the spatial scales of climatic regions and fluvial networks. Stream waters with similar dissolved organic carbon (DOC) concentrations in different climatic regions had distinctive DOM compositions, but shared 69.5% of the 3286 individual molecular formulae detected. Read report ....


General Chemistry

Parahydrogen Enhanced NMR by Pairwise Replacement Catalysis

Zhou, R.H.; Zhao, E.W.; Quinones, R.E; Bowers, C.R.; Cheng, W.; Neal, L.M.; Zheng, H.B. and Hagelin-Weaver
Published in Journal of the American Chemical Society 2015, 137 (5), 1938-1946.

Para-hydrogen can generate hyper-polarization once the two hydrogen become NMR distinguishable, a mechanism also known as parahydrogen-induced polarization (PHIP). Zhou et al have shown that by flowing parahydrogen and alkene mixture over Pt/TiO2 and Ir/TiO2 nanoparticles pairwise replacement by para-hydrogen occurs and produces intense PHIP NMR signals on the alkene without a change in molecular structure. This discovery has the potential to significantly diversify the substrates that can be hyperpolarized by PHIP for biomedical utilization. Read report ....


Origin of the Zero-Field Splitting in Mononuclear Octahedral MnIV complexes: A Combined Experimental and Theoretical Investigation

Zlatar, M.; Gruden, M.; Vassilyeva, O.; Buvaylo, E.A; Ponomaryov, A.N.; Zvyagin, S.A.; Wosnitza, J; Krzystek, J.; Garcia-Fernandez, P. and Duboc, C.
Published in Inorg. Chem. 2016, 55, 1192-1201.

This project is a truly international collaboration (7 countries, on the last count) and reports on magneto-electro-structural correlation in coordination complexes of manganese(IV). Mn(IV) is a very important ion in single-molecule magnetism, and also in biochemical cycles (for example, splitting water during photosynthesis). This project is a first systematic study to shed light on the above properties. Read report ....


Using 35Cl Solid-State NMR at Ultra-High Magnetic Fields to Study Active Pharmaceutical Ingredients: Polymorphs and Dosage Forms

Schurko, R.W., Hirsh, D.A., Veinberg, S.L., Jaroszewicz, M.J., Sandre, A.R., Namespetra, A.M.; Frydman, L.; Hung, I. and Gan, Z.
Published in Cryst Eng Comm 16, 31, 7334-7356 (2014)

35Cl solid state NMR can reveal different polymorphs without the need of large crystal in active pharmaceutical ingredients (APIs) which may exhibit different physicochemical properties such as shelf life, stability and bioavailability. Schurko et al used the 900MHz ultrawide bore NMR spectrometer to record 35Cl NMR to relate between the molecular structure and 35Cl NMR parameters. This type work is well suited for the anticipated 36T series-connected-hybrid magnet as the high field will bring even more line narrowing and sensitivity for the low-g quadrupolar nucleus. Read report ....



Novel Method To Isolate Interfacial Material

Jarvis, J.M.; Robbins, W.K.; Corilo, Y.E.; and Rodgers, R.P.
Published in Energy Fuels 29, 7058-7064 (2015).

Isolation of crude oil components that concentrate at the oil/water interface [i.e., interfacial material (IM)] facilitates their molecular identification and quantitation, which is critical for advances in optimal petroleum production and processing. For a given crude oil, the molecular composition of IM determines its emulsion stability and identifies those chemistries that disproportionately contribute to the interfacial layer. Here, we describe a scalable, simple, quick, and efficient procedure to isolate IM from petroleum crude oils and/or other organic matrices. Comparison of molecular-level characterization results obtained by the wet silica technique to that of the heavy water (Wu) method reveals a similarity between chemical functionalities (heteroatom classes) of isolated, interfacially active species. Read report ....


FT-ICR Mass Spectrometry Technology & Instrument Development

21 Tesla Fourier Transform Ion Cyclotron Resonance Mass Spectrometer: A National Resource for Ultrahigh Resolution Mass Analysis

Hendrickson, C. L.; Quinn, J. P. (NHMFL); Kaiser, N. K.; Smith, D. F.; Blakney, G. T.; Chen, T. Marshall, A. G.; Weisbrod C. R.; Beu, S. C. (S. C. Beu
Published in J. Am. Soc. Mass Spectrom. 26, 1626-1632 (2015).

We describe the design and initial performance of the first 21 tesla Fourier transform ion cyclotron resonance mass spectrometer. The 21 tesla magnet is the highest field superconducting magnet ever used for FT-ICR and features high spatial homogeneity, high temporal stability, and negligible liquid helium consumption. The instrument includes a commercial dual linear quadrupole trap front end that features high sensitivity, precise control of trapped ion number, and collisional and electron transfer dissociation. A third linear quadrupole trap offers high ion capacity and ejection efficiency, and rf quadrupole ion injection optics deliver ions to a novel dynamically harmonized ICR cell. Mass resolving power of 150,000 (m/Δm50%) is achieved for bovine serum albumin (66 kDa) for a 0.38 second detection period (see Figure 1), and greater than 2,000,000 resolving power is achieved for a 12 second detection period. Externally calibrated broadband mass measurement accuracy is typically less than 150 ppb rms, with resolving power greater than 300,000 at m/z 400 for a 0.76 second detection period. Combined analysis of electron transfer and collisional dissociation spectra results in 68% sequence coverage for carbonic anhydrase. The instrument is part of the NSF High-Field FT-ICR User Facility and is available free of charge to qualified users. Read report ....



Stable Isotope Compositions of Aquatic Flora as Indicators of Wetland Eutrophication

Gu, B.; Wang, J.; Ewe, S.; Wang, Y. and Li, Y.
Published in Ecological Engineering Volume 83, October 2015, Pages 13–18.

Changes in, and disturbances of, an ecosystem start at the molecular level. If these changes can be detected early, appropriate measures can be taken to avoid damage to the flora, fauna and the functioning of the ecosystem. In the pristine Everglades, phosphorous is the limiting nutrient and the carbon isotopic composition of macrophytes compared to soil is much different than in the Everglades near the agricultural area. This indicates that carbon isotopes can be an early indicator of euthrophication and, when combined with other environmental indicators, may be used as monitoring tools for wetland management and restoration. Read report ....


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Life Sciences


Structural Investigation of the Low Complexity Domain from FUS

Murray, D.T.; Kato, M.; McKnight, S. and Tycko, R.

Low sequence complexity domains in protein molecules once disregarded as unstructured has becoming increasingly clear that these domains are important for understanding mRNA processing and transport in healthy cells. Murray et al from NIH utilized NHMFL’s 900MHz ultrawide bore magnet and highly sensitive low-E probe to study the N-terminal low complexity domain of the Fused in Sarcoma (FUS) protein. The high sensitivity and resolution allow sequence specific assignments of fibrils formed by FUS and enable structure characterization of the low sequence complexity domains in the next step. Read report ....


Epitope Mapping of 7S Cashew Antigen in Complex with Antibody by Solution-Phase H/D Exchange Monitored by FT-ICR Mass Spectrometry

Guan, X.; Noble, K.A.; Tao, Y.; Roux, K.H.; Sathe, S.K. ; Young, N.L. and Marshall, A.G.
Published in J. Mass Spectrom. 2015, 50, 812–819.

Tree nut allergies are one of the most common, severe, and lifelong persistent food allergies among children and adults. It is the 15-25% of the protein in the cashew nut which causes anaphylaxis in which the immune system recognizes specific epitopes, or a specific piece of the antigen to which an antibody binds. Therefore, the mapping of a specific epitope is vital since it is responsible for the interaction with an antibody and determines whether an immune response ensues or not. In this report Maglab researchers used solution-phase amide backbone H/D exchange (HDX) monitored by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to map the epitope of the Cashew antigen. Guan et al identified five potential conformational epitope-contributing segments based on their protection from H/D exchange upon mAb binding. Read report ....



The Molecular Basis of the Rous Sarcoma Virus Capsid Tubular Assembly Probed by ssNMR

Jeon, J.; Qiao, X.; Huang, D.; Hung, I.; Gor'kov, P.L.; Gan, Z.H.; Zhu, F. and Chen, B.

The Rous Sarcoma virus (RSV) is the prototype of the retrovirus family that hosts many formidable pathogens including the HIV that causes AIDS. The viral genome materials are protected by a protein shell called “capsid” assembled with ~1500 copies of the capsid proteins. Jeon et al use the 900MHz ultrawide bore magnet and National MagLab’s sensitive low-E NMR probe to study the structure and dynamics of capsid protein at atomic resolution.Combined NMR results and computational simulations reveal how capsid proteins can assemble into tubular versus spherical structures, both of which are necessary for a functional infection capsid shape. Capsid assembly and dis-assembly are important for viral lifecycles and these processes can be the targets of rationally designed antiviral drug therapies. Read report ....


Characterization of a Novel Oxylipin Defense Signal in Maize

Christensen, S.A.; Kaplan, F.; Sims, J.; Huffaker, A. and Schmelz, E.A.
Published in P. Natl. Acad. Sci. U.S.A. 112/36/11407-11412.

Plant oxylipins constitute a family of oxygenated fatty acid-derived small molecules formed by enzymatic processes or chemical (auto)oxidation. Plant oxylipins demonstrate potent signaling activity in development, reproduction, resistance against abiotic stress, and modulation of innate immune responses against pathogens and pests. The focus of this report was to use NMR to elucidate the chemical structure of a novel oxylipin defense signal and to gain a better understanding of plant responses to pathogen attack. An oxylipin with a molecular weight of 240 was isolated by extraction of infected corn tissue and subsequent chromatography. Careful NMR analysis of the purified metabolite using the AMRIS 5-mm TXI cryoprobe (Bruker Corporation) and a Bruker Avance II 600 console (600 MHz for 1H and 151 MHz for 13C) confirmed a novel 14-carbon cyclopentanone derivative of 10-OPEA, termed DA0-4:0. Read report ....


A Microperfusion and In-Bore Oxygenator System Designed for Magnetic Resonance Microscopy Studies on Living Tissue Explants

Flint, J.J.; Mennon, K.; Hansen, B.; Forder, J. and Blackband, S.J.
Published in Sci Rep. 2015 Dec 15;5:18095. doi: 10.1038/srep18095.

One of the challenges of working with extremely small biological samples, even at the highest magnetics fields, is the lengthy acquisition times required to obtain images and spectra at the cellular level. Typically, microimaging is commonly performed on fixed tissuewhich is limited to structural studies. In this report, the Blackband lab is expanding the scope of microimaging studies to include live tissues and miniaturized MRI coils such that not only tissue structure can be imaged but also function and metabolism. The ability to maintain normal tissue function for 12hrs in a vertical bore system has clear implications for microimaging and NMR on the HTS and SCH magnets. Read report ....


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Magnets & Magnetic Materials

Magnet Technology and Magnet Materials

Thermal Stability of Cu-Nb Microcomposite Wires

Han, K.; Deng, L.P.; Xin, Y.; Su, Y.F.; Niu, R.M.; Yang, X.F. and Qing Liu, Q.
Published in Acta Materialia 101, p. 181-188. (2015).

The development of wires for pulsed field magnets, based on high strength Cu-Nb composite wires requires knowledge in the property changes induced by high temperature processing. It was found that the most important properties of Cu-Nb wire are retained for processing temperatures up to 500°C. Read report ....


Ceramic Insulation of Bi-2212 Round Wire for High-Field Magnet Applications

Lu, J.; McGuire, D.; Kandel, H.; Xin, Y.; Chen, P.; Jiang, J.; Trociewitz, U.; Hellstrom, E. and Larbalestier, D.
Published in IEEE Transactions on Applied Superconductivity DOI: 10.1109/TASC.2016.2539103 (2016).

Electrical insulation for Bi-2212 wires has to endure extreme circumstances during coil processing when the preferred Wind-and-React approach is used. Technology to apply thin and reliable insulation over long lengths has been elusive for over two decades. However, much progress has recently been made and there is now a realistic prospect of making the technology presented here practical and proven. Read report ....


Resistive Insert Magnet Design for the FSU Series Connected Hybrid

Toth, J.; Bole, S. and Bird, M.D.
Published in IEEE Transactions On Applied Superconductivity VOL. 26, NO. 4, JUNE 2016, 4303104.

Advantages of Series Connected Hybrids (SCH) over previous hybrid designs include more efficient use of materials and increased stability of the magnetic field. The first SCH is now operational enabling neutron scattering science at unprecedented magnetic field levels in Germany and a second system for 1 ppm solid state NMR at the NHMFL is in final construction. Read report ....


32 T Prototype Testing: Quench Behavior and Magnetic Field Record

Weijers, H.W.; Markiewicz, W.D.; Gavrilin, A.V.; Voran, A.J.; Viouchkov, Y.L.; Gundlach, S.R.; Noyes, P.D.; Abraimov, D.V.; Hannahs, S.T. and Murphy, T.P.
Published in IEEE transactions on applied superconductivity VOL. 26, NO. 4, JUNE 2016 4300807.

The 32 T magnet is expected to be the first superconducting user magnet that substantially exceeds the magnetic field range possible with traditional Low Temperature Superconductors alone by adding High Temperature Superconductor (HTS) coils that generate more than half the total field. Quench behavior, stress tolerance and field generation of full-featured prototype HTS coils. Read report ....


Quench Tests and “Self-Protecting” Behaviors of a 26 T 35 mm Multi-Width No-Insulation REBCO Magnet

Kim, K.; Kim, S.; Yoon, S. and Hahn, S.
Published in Supercond. Sci. Technol. 29 04LT04 (2016).

This is the highest field all REBCO magnet ever made and one that effectively shared the all superconducting magnet record for a few months in 2015 with the 32 T prototype coil. This No Insulation was designed to be safe on the quench conditions but the manufacturer, SuNAM, was reluctant to perform this test. They did agree to allow the test to be performed at the MagLab and the safe quenching of this high current density coil confirmed the original design calculations made by Seungyong Hahn, now of the MagLab. Read report ....


Applied Superconductivity

Current Density in Superconducting CORC® Cables Exceeding 300 A/mm2 at 20 T

van der Laan, D.C.; Weiss, J.D.; Noyes, P. and Godeke, A.
Published in Supercond. Sci. Technol. 29, 055009 (2016).

This work, in principle an evolutionary development of the CORC concept, in fact has blasted through the previous record achieved with 50 mm thick Hastelloy substrates by using the new 30 mm substrates developed in 2015 by SuperPower. It is allowing multi-kiloamp cables that can be wound on mandrels of order 50 mm. The work has recently been published (D C van der Laan, J D Weiss, P Noyes, U P Trociewitz, A Godeke, D Abraimov and D C Larbalestier, Record current density of 344 A mm−2 at 4.2 K and 17 T in CORC accelerator magnet cables. Read report ....


Persistent Superconducting Joint between Bi-2212/Ag-alloy Multifilamentary Round Wires

Chen, P.; Trociewitz, U.P.; Davis, D.; Abraimov, D.; Starch, W.; Hilton, D.; Kim, Y.; Bosque, E.; Jiang, J.; Hellstrom, E.E. and Larbalestier, D.C.

All present NMR magnets utilize persistent superconducting joints, not always perfect, to provide a temporarily stable magnetic field. So far, all HTS magnets, whether for NMR or for other purposes, have been driven magnets with very stable power supplies. In this work, a true superconducting joint has been made with V-I characteristics very close to that the strand. Two tests of joints on small coils showed decay rates very similar to the flux creep rate of short samples in a SQUID magnetometer. Paper has been written and is in final draft stage. Read report ....


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