Thursday, November 17, 2016

Publications 2016

1.        Bao, Q., Zhang, M., Wu, L., Wang, J., Xia, Y., Qian, D., Liu, H., Hy, S., Chen, Y., An, K., Zhu, Y., Liu, Z., and Meng, YS.,  “Gas-solid interfacial modification of oxygen activity in layered oxide cathodes for lithium-ion batteries" Nat. Comm., 7 12108 (2016).
2.        Brahlek, M. J.; Koirala, N.; Liu, J.; Yusufaly, T. I.; Salehi, M.; Han, M-G.; Zhu, Y.; Vanderbilt, D.; Oh, S., “Tunable inverse topological heterostructure utilizing (Bi1-xInx)(2)Se-3 and multichannel weak-antilocalization effect”, Phys. Rev. Rev. B, 93 125416 (2016).
3.        Brahlek, M., Koirala, N., Salehi, M., Moon, J., Zhang, W., Li, H., Zhou, X., Han, M.-G., Wu, L., Emge, T., Lee, H.-D., Xu, C., Rhee, S. J., Gustafsson, T., Armitage, N., Zhu, Y., Dessau, D. S., Wu, W., Oh, S., “Disorder-driven topological phase transition in Bi2Se3 films”, Physical Review B (2016) accepted.
4.        Cheng, S., Li,M., Meng, Q., Duan, W., Zhao, Y.G., Sun, X.F.,  Zhu, Y.,  Zhu, J., “Electronic and crystal structure changes induced by in-plane oxygen vacancies in multiferroic YMnO3”, Phys. Rev. B 93 054409 (2016).
5.        Dai, Y.; Fang, Y.; Cai, S.; Wu, L.; Yang, W.; Yan, H., Xie, J.; Zheng, J-C.; Takeuchi, E., and Zhu, Y. “Surface modified pinecone shaped hierarchical structure fluorinated mesocarbon microbeads for ultrafast discharge and improved electrochemical performances”, Journal of The Electrochemical Society, in press.
6.        Das, P. K.; Di S., D.; Vobornik, I.; Fujii, J.; Okuda, T.; Bruyer, E.; Gyenis, A.; Feldman, B. E.; Tao, J.; Ciancio, R.; Rossi, G.; Ali, M. N.; Picozzi, S.; Yadzani, A.; Panaccione, G.; Cava, R. J., “Layer-dependent quantum cooperation of electron and hole states in the anomalous semimetal WTe2,” Nature Communications 7, 10847, (2016).
7.        Garlow, J. A., Barrett, L., Wu,L., Kisslinger, K., Zhu, Y., and Pulecio, J.F., “Large-Area Growth of Turbostratic Graphene on Ni(111) via Physical Vapor Deposition”, Scientific Report, 6:19804 (2016).
8.        Han, M.-G.; Garlow, J. A.; Bugnet, M.; Divilov, S.; Marshall, S. J. M.; Wu, L.; Dawber, M.; Fernandez-Serra, M.; Botton, G. A.; Cheong, S.-W.; Walker, F. J.; Ahn, C. H.; and Zhu, Y., “Coupling of bias-induced crystallographic shear planes with charged domain walls in ferroelectric oxide thin films”, Phys. Rev. B (2016) in press.
9.        Han, L.; Meng, Q.; Wang, D.; Zhu, Y.; Wang, J.; Du, X.; Stach, E.; and Xin, H.; “Interrogation of bimetallic particle oxidation in three dimensions at the nanoscale, Nature Comm.,  (2016) in press.
10.     He, K., Zhang, S., Li, J., Meng, Q., Zhu, Yizhou, Hu, E., Sun, K., Yun, H., Yang, XQ., Zhu, Yimei, Gan, H., Mo, Y., Stach, EA., Murray, CB., Su, D., “Visualizing non-equilibrium lithiation of spinel oxide via in situ transmission electron microscopy”, Nature Comm. 7, 11441(2016).
11.     Hoch, LB., He, L., Qiao, Q., Liao, K., Reyes, LM., Zhu, Y., and Ozin, GA., "Effect of precursor selection on photocatalytic performance of indium oxide nanomaterials for CO2 reduction" Chem. of Mater, 28 4160-4168 (2016).
12.     Hoch, LB.; Szymanski, P.; Ghuman, KK.; He, L.; Liao, K.; Qiao, Q.; Zhu, Y.; El-Sayed, MA.; Singh, CV.; and Ozin, GA.; “Carrier Dynamics and the Role of Surface Defects: Designing a Photocatalyst for Gas-Phase CO2 Reduction,” Proc. of Natl Acad. of Sci., (2016), in press.
13.     Hu, Jue; Wu, Lijun; Kuttiyiel, Kurian; Goodman, Kenneth; Zhang, Chengxu; Zhu, Yimei; Vukmirovic, Miomir; White, Michael; Sasaki, Kotaro; Adzic, Radoslav, “Increasing Stability and Activity of Core-shell Catalysts by Preferential Segregation of Oxide on Edges and Vertexes: Oxygen Reduction on Ti-Au@Pt/C”, J. Am. Chem. Soc. 138 (29), 9294–9300 (2016).
14.     Kim, J.; Nam, H.; Li, G.; Karki, AB.; Wang, Z.; Zhu, Y.; Shih, C-K.; Zhang, J.; Jin, R.; and Plummer, EW.; “Interrogating the superconductor Ca10(Pt4As8)(Fe2−xPtxAs2)5 Layerby-layer”,  Scientific Reports, 6, 35365 (2016).
15.     Li, J., He, K., Meng, Q., Li, X., Zhu, Yizhou, Hwang, S., Sun, K., Gan, H., Zhu, Yimei, Mo, Y., Stach, EA., and Su, D., “Kinetic phase evolution of spinel cobalt oxide during lithiation”,  ACS nano, 10, 9577-9585 (2016).
16.     Li, J.; Yin, W.; Wu, L.; Zhu, P.; Konstantinova, Tao, J.; Yang, J..; Cheong, S-W.; Carbone, F.; Misewich, J.; Hill, J.; Wang, X.; Cava, R.; and Zhu. Y.; “Dichotomy in ultrafast atomic dynamics as direct evidence of polaron formation in manganites”, NPJ Quantum Materials, in press
17.     Ling, X., Lin, Y., Ma, Q., Wang, Z., Song, Y., Yu, L., Huang, S., Fang, W., Zhang, X., Hsu, AL., Bie, Y., Lee, Y-H., Zhu, Y., Wu, L., Li, J., Jarillo-Herrero, P., Dresselhaus, M., Palacios, T., and Kong, J., “Parallel Stitching of 2D Materials”, Adv. Mater. 28, 2322–2329 ( (2016).
18.     Liu, J., Yin, L., Wu, L., Bai, J., Bak, S-M., Yu, X., Zhu, Y., Yang, X-Q., and Khalifah, PG., "Quantification of honeycomb number-type stacking: application to NaNiBiO cathodes for Na-ion batteries", Inorganic Chemistry, 55, 8478−8492 (2016).
19.     Luo, M.; Ruditskiy, A.; Peng, H-C; Tao, J.; Figueroa-Cosme, L.; He, Z.; Xia, Y., “Penta-Twinned Copper Nanorods: Facile Synthesis via Seed-Mediated Growth and Their Tunable Plasmonic Properties,” Advanced Functional Materials 26, 1209 (2016).
20.     Luo, H.; Xie, W.; Tao, J.; Pletikosic, I.; Valla, T.; Sahasrabudhe, G. S.; Osterhoudt, G.; Sutton, E.; Burch, K. S.; Seibel, E. M.; Krizan, J. W.; Zhu, Y.; Cava, R. J., “Differences in Chemical Doping Matter: Superconductivity in Ti1-xTaxSe2 but Not in Ti1-xNbxSe2,” Chemistry of Materials 28, 1927, (2016).
21.     Lv, T.; Yang, X.; Zheng, Y.; Huang, H.; Zhang, L.; Tao, J.; Pan, L.; Xia, Y., “Controlling the Growth of Au on Icosahedral Seeds of Pd by Manipulating the Reduction Kinetics”, The Journal of Physical Chemistry 120 (37), 20768–20774 (September, 2016)
22.     Ozaki, T.; Wu, L.; Zhang, C.; Jaroszynski, J.; Si, W.; Zhou, J.; Zhu, Y.; and Li, Q. "A route for a strong increase of critical current in nano strained iron-based superconductors", Nature communications 7 13036 (2016).
23.     Poyraz, A. S.; Huang, J.; Cheng, S.; Bock, D. C.; Wu, L.; Zhu, Y.; Marschilok, A. C.; Takeuchi, K. J.; and Takeuchi, E. S. “Effective Recycling of Manganese Oxide Cathodes for Lithium Based Batteries”, Green Chem., 18, 3414-3421 (2016).
24.     Poyraz, A. S.; Huang, J.; Cheng, S.; Bock, D. C.; Wu, L.; Zhu, Y.; Marschilok, A. C.; Takeuchi, K. J.; and Takeuchi, E. S. “Effective Recycling of Manganese Oxide Cathodes for Lithium Based Batteries”, Green Chem., 2016, DOI: 10.1039/C6GC00438E.
25.     Qiu, J., Ha, G., Jing, C., Baryshev, S.V., Reed,  B.W., Lau, L.W., Zhu, Y., “GHz Laser-free Time-resolved Transmission Electron Microscopy: a Stroboscopic High-duty-cycle Method”, Ultramicroscopy 161, 130-136 (2016).
26.     Qiu, B.; Zhang, M.; Wu, L1.; Wang, J.; Xia, Y.; Qian, D.; Liu, H Zhu, Y.; Liu, Z., .and Meng, Y. S.; “Gas–solid interfacial modification of oxygen activity in layered oxide cathodes for lithium-ion batteries”, Nature Comm., 7 12108 (2016).  1 contributed equally as the first author.
27.     Scofield, M. E.; Koenigsmann, C.; Bobb-Semple, D.; Tao, J.; Tong, X.; Wang, L.; Lewis, C. S.; Vukmirovic, M. B.; Zhu, Y.; Adzic, R. R.; Wong, S. S., “Correlating the chemical composition and size of various metal oxide substrates with the catalytic activity and stability of as-deposited Pt nanoparticles for the methanol oxidation reaction,” Catalysis Science & Technology 6, 2435 (2016).
28.     Sutter, P.; Tenney, SA.; Ivars-Barcelo, F.; Wu, L.; Zhu, Y.; and Sutter, E.; “Alloy oxidation as a route to chemically active nanocomposites of gold atoms in a reducible oxide matrix”, Nanoscale Horizons, 1 212-219 (2016).
29.     Tao, J.; Sun, K.; Yin, W. G.; Wu, L.; Xin, H.; Wen, J. G.; Luo, W.; Pennycook, S. J.; Tranquada, J. M. and Zhu, Y., “Direct observation of electronic-liquid-crystal phase transitions and their microscopic origin in La1/3Ca2/3MnO3”, Scientific Reports (2016) in press.
30.     Thenuwara, AC.; Shumlas, SL.; Attanayake, NH.; Aulin, YV.; McKendry, IG.; Qiao, Q.; Zhu, Y.; Borguet, E.; Zdilla, MJ.; and Stongnin, DR.; “Intercalation of Cobalt into the Interlayer of Birnessite Improves Oxygen Evolution Catalysis,” ACS Catalysis, 6, 7739 (2016)
31.     Wang, Z.; Tao, J.; Yu, L.; Guo, H.; Chen, L.; Han, M-G.; Wu, L,; Xin, H.; Kisslinger, K.; Plummer, EW.; Zhang, J.; and Zhu, Y.; “Anomalously Deep Polarization in SrTiO3(001) Interfaced with an Epitaxial Ultrathin Manganite Film”,   Phys. Rev B, 94 155307(2016).
32.     Wang, A.; Graf, D.;  Wu, L.; Wang, K.; Bozin, E.; Zhu, Y.; and Petrovic, C. “Interlayer electronic transport in CaMnBi2 antiferromagnet”, Phys. Rev. B 94, 125118 (2016).
33.     Wang, A.; Wu, L.; Ivanovski, V. N.; Warren, J. B.; Tian, J.; Zhu, Y.; and Petrovic, C. “Critical current density and vortex pinning in tetragonal FeS1−xSex (x = 0,0.06)”, Phys. Rev. B 94, 094506 (2016).
34.     Xu, F., Ge, B., Chen, J., Nathan, A., Xin, H., Ma, H., Min, H., Zhu, C., Xia, W., Li, Z., Li, S., Yu, K., Wu, L., Cui, Y., Sun, L., Zhu, Y., "Scalable shear-exfoliation of high-quality phosphorene nanoflakes with reliable electrochemical cycleability in nano batteries", 2D Materials, 3, 025005 (2016).
35.     Xu, F., Li, Z., Wu, L., Meng, Q., Xin, H., Sun, J., Ge, B., Sun, L., Zhu, Y., “In situ TEM probing of crystallization form-dependent sodiation behavior in ZnO nanowires for sodium-ion batteries”, Nano Energy, (2016).
36.     Xu, F.; Ma, H.; Lei, S.; Sun, J.; Chen, J.; Ge, B.; Zhu, Y.; and Sun, L.; “In situ TEM visualization of superior nanomechanical flexibility of shear-exfoliated phosphorene”, Nanoscale, 8, 13603 (2016).
37.     Zhang, B., Wu, L., Yin, WG., Sun, CJ., Yang, P., Venkatesan, T., Chen, J., Zhu, Y., and Chow, GM., “Interfacial Coupling-Induced Ferromagnetic Insulator Phase in manganite film”, Nano Lett. 16, 4174−4180 (2016).
38.     Zhang, W.,  Bock, DC.,  Pelliccione, JC., Li, Y., Wu, L., Zhu, Y., Marschilok, AC., Takeuchi, KJ., Takeuchi, ES., Wang, F., “Insights into magnetite structural changes associated with multiple electron/lithium ion transfers”, Advanced Energy Materials, 1502471 (2016).
39.     Zhang, W., Li, M., Chen, A., Li, L., ZhuY., Xia, Z., Lu, P., Boullay, P., Wu, L., Yimei Zhu, MacManus-Driscoll, LJ., Jia, Q., Zhou, H., Narayan, J., Zhang, X., and Wang, H., “Two-Dimensional Layered Oxide Structures Tailored by Self- Assembled Layer Stacking via Interfacial Strain”, ACS Appl. Mater. Interfaces, 8 16845-16851 (2016).
40.     Zhao, J.; Zhang, W.; Huq, A.; Misture, ST.; Zhang, B.; Guo, S.; Wu, L.; Zhu, Y.; Chen, Z.; Amine, K.; Pan, F.; Bai, J.; and Wang F. “In Situ Probing and Synthetic Control of Cationic Ordering in Ni-Rich Layered Oxide Cathodes”, Adv. Energy Mater. 1601266 (2016).

Tuesday, December 8, 2015

Publications 2015

1.        Abeykoon, A. M. M.;  H. Hu, L. Wu, Y. Zhu and S. J. L. Billinge, “Calibration and data collection protocols for reliable lattice parameter values in electron pair distribution function studies,” J. of Appl. Crystallography 48, 244-251 (2015)
2.        Ciston, J.;  H. G. Brown, A. J. D'Alfonso, P. Koirala, C. Ophus, Y. Lin, Y. Suzuki, H. Inada, Y. Zhu, L. J. Allen, L. D. Marks, “Surface determination through atomically resolved secondary-electron imaging”, Nat. Comm., 6, 7358 (2015)
3.        Egerton, R.F.; Konstantinova, T.;  Zhu, Y.; “Analysis of Beam-Sensitive Materials by Electrons and X-rays”, in: M. Berz, P.M. Duxbury, K. Makino, C.-Y. Ruan (Eds.), Femtosecond Electron Imaging and Spectroscopy 2013, Advances in Imaging and Electron Physics 191, pp. 70–80, Elsevier, (2015).
4.        Jasion, D., Barforoush, J.M., Qiao, Q., Zhu, Y., Ren, S., and Leonard, KC.,  "Low-Dimensional Hyperthin FeS2 Nanostructures for Efficient and Stable Hydrogen Evolution Electrocatalysis" ACS Catalysis, 5, 6653 (2015).
5.        Koirala, N.;  Brahlek, M. J.; Salehi, M.; Wu, L.; Dai, J.; Waugh, J.; Nummy, T.; Han, M-G.; Moon, J.; Zhu, Y.; Dessau, D.; Wu, W.; Armitage, N. P.; and Oh, S., “Record Surface State Mobility and Quantum Hall Effect in Topological Insulator Thin Films via Interface Engineering”, Nano Lett., 15, 8245−8249 (2015)
6.        Li, M.;  C-Z. Chang, L. Wu, J. Tao, W. Zhao, MHW. Chan, JS. Moodera, J. Li, and Y. Zhu, “Experimental Verification of the Van Vleck Nature of Long-Range Ferromagnetic Order in the Vanadium-Doped Three-Dimensional Topological Insulator Sb2Te3”, Phys. Rev. Lett., 114, 146802 (2015).
7.        Li, M.; C-Z. Chang, BJ. Kirby, M. Jamer, W. Cui, L. Wu, P. Wei, Y. Zhu, D. Heiman, J. Li, and JS. Moodera, "Proximity-driven enhanced magnetic order at ferromagnetic-insulator--magnetic-topological-insulator interface", Phys. Rev. Lett. 115, 087201 (2015).
8.        Li, M., W. Cui, L. Wu, Q. Meng, Y. Zhu, Y. Zhang, W. Liu, and Z. Ren, "Topological effect of surface plasmon excitation in gapped isotropic topological insulator nanowires", Can. J. Phys. 93: 591-598 (2015).
9.        Luo, H. X.;  Xie, W. W. Xie, J. Tao, H. Inoue, A. Gyenis, J. W. Krizan, A. Yazdani, Y. M. Zhu, R. J. Cava, “Polytypism, polymorphism, and superconductivity in TaSe2-xTex,” Proc. of Nat’l. Acad. Sci. 112, E1174-1180, (2015)
10.     Luo, H. X.; Krizan, J. W.; Seibel, E. M.; Xie, W. W.; Sahasrabudhe, G. S.; Bergman, S. L.; Phelan, B. F.; Tao, J.; Wang, Z.; Zhang, J. D.; Cava, R. J., "Cr-Doped TiSe2 - A Layered Dichalcogenide Spin Glass"Chemistry of Materials, 27, 6810, (2015)
11.     Ma, J.; S-H Bo, L. Wu, Y. Zhu, CP. Grey, and PG. Khalifah, “Ordered and Disordered Polymorphs of Na(Ni2/3Sb1/3)O2: Honeycomb-Ordered Cathodes for Na-Ion Batteries,” Chemistry of Materials 27 (7), 2387–2399 (2015).
12.     Meng, Q.;  M. G. Han, J. Tao, G. Y. Xu, D. O. Welch, Y. M. Zhu, “Velocity of domain-wall motion during polarization reversal in ferroelectric thin films: Beyond Merz's Law,” Phys. Rev. B 91, 054104 (2015)
13.     Meng, Q.; L. Wu, DO. Welch, and Y. Zhu, “Lattice vibrations in the Frenkel-Kontorova model. I. Phonon dispersion, number density, and energy”, Phys. Rev. B 91, 224305 (2015).
14.     Meng, Q.; L. Wu, DO. Welch, and Y. Zhu, “Lattice vibrations in the Frenkel-Kontorova Model. II. Thermal conductivity”, Phys. Rev. B 91, 224306 (2015).
15.     Mildner, S.; Beleggia, M.; Mierwaldt, D.; Hansen, T.W.; Wagner, J.B.; Yazdi, S.; Kasama, T.; Ciston, J.; Zhu, Y.; Jooss, Ch.; "Environmental TEM Study of Electron Beam Induced Electrochemistry of Pr0.64Ca0.36MnO3 Catalysts for Oxygen Evolution", J. of Phys. Chem. C, 1195301-5310 (2015).
16.     Que, Y.; Y. Zhang, Y. L. Wang, L. Huang, W. Y. Xu, J. Tao, L. J. Wu, Y. M. Zhu, K. Kim, M. Weinl, M. Schreck, C. M. Shen, S. X. Du, Y. Q. Liu and H.-J. Gao, “Graphene-Silicon Layered Structures on Single-Crystalline Ir(111) Thin Films,” Advanced Materials Interfaces 2, 1400543, (2015)
17.     Rodriguez, J. A.;  R. Si, J. Evans, W. Q. Xu, J. C. Hanson, J. Tao, Y. M. Zhu, “Active gold-ceria and gold-ceria/titania catalysts for CO oxidation: From single-crystal model catalysts to powder catalysts,” Catalysis Today 240, 229-235, (2015).
18.     Shi, X.; J. Yang, L. Wu, J. R. Salvador, W.L. Villaire, D. Haddad, J. Yang, Y. Zhu, and Q. Li, "Band Structure Engineering and Thermoelectric Properties of Charge-Compensated Filled Skutterudites", Scientific Report,  5 14641 (2015).
19.     Ugur, A.; F. Katmis, M. Li, L. Wu, Y. Zhu, KK. Varanasi, and KK. Gleason, “Low-Dimensional Conduction Mechanisms in Highly Conductive and Transparent Conjugated Polymers”, Adv. Mater., DOI: 10.1002/adma.201502340 (2015).
20.     Wei, Z.; W. Zhang, F. Wang, Q. Zhang, B. Qiu, S. Han, Y. Xia, Y. Zhu, Z. Liu, “Eliminating Voltage Decay of Lithium-Rich Li1.14Mn0.54Ni0.14Co0.14O2 Cathodes by Controlling the Electrochemical Process”, Chemistry - A European J. 21, 7503-7510 (2015).
21.     Wu, D.; Zhao, L-D.; Tong, X.; Li, W.; Wu, L.; Tan, Q.; Pei, Y.; Huang, L.; Li, J-F.; Zhu, Y.; Kanatzidis, MG.; He, J.; “Superior thermoelectric performance in PbTe-PbS pseudo-binary: extremely low thermal conductivity and modulated carrier concentration”, Energy & Environmental Science, 8 2056-2068 (2015).
22.     Wu, L.; Feng X., Zhu, Y., AB. Brady, J. Huang, JL. Durham, E. Dooryhee, AC. Marschilok, ES. Takeuchi, and KJ. Takeuchi, “Structural Defects of Silver Hollandite, AgxMn8Oy, Nanorods: Dramatic Impact on Electrochemistry”, ACS Nano, ACS Nano 9 8430-8439, (2015).   
23.     Wei, Z.; Zhang, W.; Wang, F.; Zhang, Q.; Qiu, B.; Han, S.; Xia, Y.; Zhu, Y.; Liu, Z.;          “Eliminating Voltage Decay of Lithium-Rich Li1.14Mn0.54Ni0.14Co0.14O2 Cathodes by Controlling the Electrochemical Process”, Chem.- A European Journal 21, 7503-7510 (2015).
24.     Yan, D. H.; Tao, J.; Kisslinger, K.; Cen, J. J.; Wu, Q. Y.; Orlov, A.; Liu, M. Z., “The role of the domain size and titanium dopant in nanocrystalline hematite thin films for water photolysis”, Nanoscale, 7, 18515-18523 (2015)
25.     Yin, Y-W.; Huang, W-C.; Liu, Y-K.; Yang, S-W.; Dong, S-N.; Tao, J.; Zhu, Y-M.; Li, Q.; Li, X.-G.;  “Octonary Resistance States in La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 Multiferroic Tunnel Junctions”, Adv. Electronic Mater. Nov.  1 1500183 (2015).
26.     Zhang, B., C.-J. Sun, W. Lu, T. Venkatesan, M.-G. Han, Y. Zhu, J. Chen, and G. M. Chow, “Electric-field-induced strain effects on the magnetization of a Pr0.6Sr0.33MnO3 film”, Phys. Rev. B 91, 174431 (2015).
27.     Zheng, H.; Meng, Y. S.; and Zhu, Y.; “Frontiers of in situ electron microscopy”, MRS BULLETIN, 40, 12-18, (2015).
28.     Zhu, C.; Min, H.; Xu, F.; Chen, J.; Dong, H.; Tong, L.; Zhu, Y.; Sun, L.; “Ultrafast electrochemical preparation of graphene/CoS nanosheet counter electrodes for efficient dye-sensitized solar cells”, RSC Adv., 5, 85822–85830 (2015).
29.     Zhu, P.; Y. Zhu, Y. Hidaka, L. Wu, J. Cao, H. Berger, J. Geck, R. Kraus, S. Pjerov, Y. Shen, R. Tobey, J.P. Hill, and X.J. Wang, “Femtosecond time-resolved MeV electron diffraction”, New J. of Physics, 17 063004 (2015).
30.     Zhu, Y. and H. Durr, “The future of electron microscopy”, Physics Today, 68 32-38 (2015).

Thursday, June 18, 2015

A New Look at Surface Chemistry

Most materials correlate with other materials by their surfaces, that are mostly opposite in both structure and chemistry from a bulk of a material. Many critical processes take place during surfaces, trimming from a catalysts used for a era of energy-dense fuels from object and CO dioxide, to how bridges and airplanes rust.
“In essence, a aspect of each element can act as a possess nanomaterial cloaking that can severely change a chemistry and behavior,” Ciston says. “To know these processes and urge element opening it is critical to know how a atoms are organised during surfaces. While there are now many good methods for receiving this information for rather prosaic surfaces, when a surfaces are severe many now accessible collection are singular in what they can reveal.”
“The beauty of this technique is that we can picture aspect atoms and bulk atoms simultaneously,” says co-author Zhu, a scientist during Brookhaven National Laboratory. “Currently nothing of any existent methods can grasp this.”
Scanning nucleus microscopy (SEM) is an glorious technique for investigate surfaces yet typically provides information customarily about topology during nanoscale resolution. A rarely earnest new chronicle of scanning nucleus microscopy, called “high-resolution scanning nucleus microscopy,” or HRSEM, extends this fortitude to a atomic scale and provides information on both aspect and bulk atoms simultaneously, maintaining most of a aspect attraction of normal SEM by delegate electrons.
Secondary electrons are a outcome of a rarely energized lamp of electrons distinguished a element and causing atoms in a element to evacuate appetite in a form of electrons rather than photons. As a vast apportionment of delegate electrons are issued from a aspect of a element in further to a bulk they are good resources for receiving information about atomic aspect structure. However, a aspect selectivity of HRSEM has never been entirely exploited.

Ciston is a lead and analogous author of a paper describing this new methodical process in a biography Nature Communications. The essay is patrician “Surface Determination by Atomically Resolved Secondary Electron Imaging.” Other co-authors are Hamish Brown, Adrian D’Alfonso, Pratik Koirala, Colin Ophus, Yuyuan Lin, Yuya Suzuki, Hiromi Inada, Yimei Zhu, Les Allen, and Laurence Marks.

Monday, April 13, 2015

Long-Sought Magnetic Mechanism Observed in Exotic Hybrid Materials

Scientists have measured the subatomic intricacies of an exotic phenomenon first predicted more than 60 years ago. This so-called van Vleck magnetism is the key to harnessing the quantum quirks of topological insulators—hybrid materials that are both conducting and insulating—and could lead to unprecedented electronics. 
“Our experiment is the first to show conclusive evidence of van Vleck magnetism, which mediates the magnetic properties of topological insulators,” said MIT and Brookhaven Lab Ph.D. student Mingda Li, lead author on the study. “Synthesis and characterization techniques have finally caught up to seminal theoretical work, and we are thrilled to have performed this groundbreaking research.” The collaboration—including the U.S. Department of Energy’s Brookhaven National Laboratory, MIT, and Pennsylvania State University—used cutting-edge electron microscopy facilities at Brookhaven Lab to pinpoint this never-before-seen behavior. The results were published online April 9, 2015, in the journal Physical Review Letters.
Tunable topological insulators could lay the foundation for new generations of spintronics, quantum computers, and ultra-efficient semiconductor devices (see sidebar).

Van Vleck’s volleyball

Classical materials tend to conduct electricity or insulate against it—think rubber versus copper. Topological insulators, however, live in both worlds: the bulk is insulating, but the surface is highly conductive. The relationship between these competing qualities introduces strange phenomena, especially in the surface electrons.
“The surface electrons—called Dirac electrons—exhibit the light-like mobility and extreme stability that enables so many exciting potential applications,” Li said. “But these electrons cannot be controlled directly. That’s where van Vleck magnetism comes in, to induce and harness Dirac electrons.”
Imagine an endless game of volleyball between perfectly matched opponents. Now replace the players with magnetic ions and the ball with a free electron—that interplay mirrors magnetism in traditional semiconductors. Interrupting the game or shifting the behavior of that free electron, which is key to semiconductor applications, is a relatively simple task.
In topological insulators, however, that volleyball game never gets going. The magnetic action is contained within a single crystal structure—no back-and-forth and no free electrons. This subtle, intra-atomic magnetism behaves like a lone player engaging in a virtual volley. In fact, a rogue volleyball (free electron) would ruin the game. 
“Those all-important outer electrons can only be influenced through the topological insulator’s core electrons,” Li said. “The outer electrons can ‘feel’ the effect of energy or magnetic fields on the core. That conversation between core and shell is mediated by van Vleck magnetism.” 
John Hasbrouck van Vleck, considered the father of modern magnetism, won the 1977 Nobel Prize in Physics for his quantum revisions of magnetism theory. His groundbreaking work included predicting this internal magnetism, which has been notoriously difficult to detect—until now.
Congratualtions Mingda!!
Full article:
In addition, these findings have been featured on a number of other science news media websites:

Friday, February 27, 2015

New Path to Loss-Free Electricity

The Science

Electric current flows without any resistance in a superconducting state thanks to a surprising redistribution of bonding electrons and the associated electronic and atomic behavior after substitution of some cobalt atoms for iron in barium iron arsenide.

The Impact

This discovery of substitution-induced charge redistribution demonstrates the prominent role of bonding (and the associated electron fluctuations) in the emergence of superconductivity in iron-based alloys. It suggests a new route for finding higher performance superconductors through engineering and optimization of the electron density among the atoms in the material.


The flow of current in ordinary metals and other materials that conduct electricity is composed of electrons; however, the charge carriers are scattered when they conduct electricity, resulting in dissipation and energy loss, typically in the form of heat. In a superconductor, the electrons form into pairs that allow them to move through the material without resistance, eliminating the energy lost and thus increasing the efficient use of electricity. The challenge in creating such electron pairs is overcoming the natural tendency for electrons to repel each other. One solution is to utilize electronic polarizability that can yield an attractive interaction between electrons, thus allowing pair formation and the potential for loss-free current flow. Such a mechanism was proposed almost five decades ago, but it was never experimentally verified. Using electron diffraction with subatomic precision, scientists at Brookhaven National Laboratory have mapped out the redistribution of orbital electrons in barium iron arsenide, with and without cobalt substitution. The results reveal a remarkable increase in charge distribution around the iron and arsenic atoms as cobalt is incorporated into the material. Electron energy loss spectroscopy was carried out to determine the charge carrier-injection effect of cobalt substitution, while density functional theory was used to model electronic and atomic behavior. The induced charge redistribution around the iron and arsenic atoms after cobalt substitution suggests that the strongly coupled bond-electron fluctuation and charge separation may provide a new mechanism for high-temperature superconductivity. These results may guide the design of new superconductors.

Monday, February 23, 2015

Meet Joe Garlow

When Joseph Garlow graduated from Ward Melville High School he was fairly certain what career path he wanted to follow. So, he headed off to the State University of New York (SUNY) at Cortland to work toward a degree in sports medicine and orthopedics. Shortly after his arrival, though, he became interested in biomedical engineering and nanotechnology. Through a series of transformations, including a stint as a student intern at Brookhaven Lab, he’s spun those interests in to a possible future career potential with a big impact on energy.
“I had a strong background in biology, and I come from a family of engineers, so I applied to the biomedical engineering program at Stony Brook University,” said Garlow. “I was really happy to be accepted to the Stony Brook program.” 
In addition to his regular Stony Brook classes, Garlow found a job as a research assistant in Professor Balaji Sitharaman’s multi-functional nano and supramolecular biosystems lab. There, he focused on two successful projects involving carbon nanotubes, graphene nanoribbons, graphene nanoparticles, and graphene-anode microbial fuel cells. The project results indicated that microbial fuel cells produce 10 times the power output of commercially available fuel-cell anodes, which may lead to more efficient fuel-cell technologies.
But Garlow didn’t only spend time in the classroom or lab. Soon after joining the student ranks at Stony Brook, he recognized the importance of helping underprivileged teenagers become interested in science and technology. He joined the school’s Science and Technology Entry Program (STEP) and worked as a mentor preparing and guiding students to pursue careers in science and engineering. His outreach efforts also included helping students prepare for science competitions. Garlow also served as a judiciary working with the dean of students, faculty, and other student leaders on best practices for allocations of funds for student organizations. 
Garlow’s introduction to Brookhaven started in 2012 when he came to the Lab as an undergraduate intern with post-doc Javier Pulecio in Yimei Zhu’s group in the Lab’s Condensed Matter Physics and Materials Science Department (CMPMS). 
“From then on, I was definitely hooked on science,” said Garlow.
In 2013, Garlow stayed on as a member of Zhu’s team through the U.S. Department of Energy’s Science Undergraduate Laboratory Internship (SULI) program. Zhu’s work suited Garlow’s research interests perfectly. 
“Joe had his research goals all lined up when we first met to discuss a mentorship,” said Zhu, who is also an adjunct professor at Stony Brook. “He is extremely motivated and it took very little convincing for me to welcome him to our lab. He is a valued member of our team.”
Along with Zhu and Pulecio, Garlow uses transmission electron microscopy and raman spectroscopy to explore the atomic structures and properties of precisely aligned graphene layers grown on nickel films. This research landed Garlow a spot as first author on a paper submitted to Scientific Reports.   
“Doing hands-on research at the Lab has surpassed all of my expectations and has given me a solid background not just in the actual science, but how it feels to work on a team of scientists who are seeking knowledge and discoveries,” said Garlow. “The experience is nothing short of amazing. I am grateful for this opportunity from Brookhaven’s Office of Educational Programs and scientists at the Lab.”
Currently working toward his Ph.D. at Stony Brook under the leadership of Zhu, Garlow says his current research focuses on charge, spin, and lattice correlations in layered materials such as perovskite oxides. These types of materials can display intriguing (and potentially useful) electrical and magnetic properties, including superconductivity, the flow of electrical current with no resistance; giant magnetoresistance, which renders a significant difference in electrical resistance depending on the alignment of magnetization within materials; and multiferroics, where intriguing, electronic and magnetic properties can be manipulated. These unusual properties may have significant implications in the emerging field of spintronics (a new type of technology which may revolutionize the future of computing), and lead to applications that will create faster and more efficient computers and new electronic and energy technologies.  
“Being mentored by Dr. Zhu and the many other Lab researchers has given me an opportunity to fully discover how fascinating nanotechnology and physics can be, and how the work we do today impacts our future,” said Garlow. “Brookhaven Lab’s brilliant scientists and state-of-the-art equipment afforded me the opportunity to accomplish much more than I anticipated. I am already looking forward to more scientific adventures and discoveries that will make a difference in our world now and to future generations.”
“For now, I am using most of my energy to focus on my studies and research,” added Garlow. “But, perhaps in the future I will again have the chance to join my rugby friends on the field. Hey, a guy still needs to have some fun!” he said.

Monday, January 12, 2015

Unstoppable Magnetoresistance

Mazhar Ali, a fifth-year graduate student in the laboratory of Bob Cava, the Russell Wellman Moore Professor of Chemistry at Princeton University, has spent his academic career discovering new superconductors, materials coveted for their ability to let electrons flow without resistance. While testing his latest candidate, the semimetal tungsten ditelluride (WTe2), he noticed a peculiar result.
Ali applied a magnetic field to a sample of WTe2, one way to kill superconductivity if present, and saw that its resistance doubled. Intrigued, Ali worked with Jun Xiong, a student in the laboratory of Nai Phuan Ong, the Eugene Higgins Professor of Physics at Princeton, to re-measure the material’s magnetoresistance, which is the change in resistance as a material is exposed to stronger magnetic fields.
“He noticed the magnetoresistance kept going up and up and up—that never happens.” said Cava. The researchers then exposed WTe2 to a 60-tesla magnetic field, close to the strongest magnetic field mankind can create, and observed a magnetoresistance of 13 million percent. The material’s magnetoresistance displayed unlimited growth, making it the only known material without a saturation point. The results were published on September 14 in the journal Nature.
Electronic information storage is dependent on the use of magnetic fields to switch between distinct resistivity values that correlate to either a one or a zero. The larger the magnetoresistance, the smaller the magnetic field needed to change from one state to another, Ali said. Today’s devices use layered materials with so-called “giant magnetoresistance,” with changes in resistance of 20,000 to 30,000 percent when a magnetic field is applied. “Colossal magnetoresistance” is close to 100,000 percent, so for a magnetoresistance percentage in the millions, the researchers hoped to coin a new term.
Their original choice was “ludicrous” magnetoresistance, which was inspired by “ludicrous speed,” the fictional form of fast-travel used in the comedy “Spaceballs.” They even included an acknowledgement to director Mel Brooks. After other lab members vetoed “ludicrous,” the researchers considered “titanic” before Nature editors ultimately steered them towards the term “large magnetoresistance.”
Terminology aside, the fact remained that the magnetoresistance values were extraordinarily high, a phenomenon that might be understood through the structure of WTe2. To look at the structure with an electron microscope, the research team turned to Jing Tao, a researcher at Brookhaven National Laboratory.
“Jing is a great microscopist. They have unique capabilities at Brookhaven,” Cava said. “One is that they can measure diffraction at 10 Kelvin (-441 °F). Not too many people on Earth can do that, but Jing can.”
Electron microscopy experiments revealed the presence of tungsten dimers, paired tungsten atoms, arranged in chains responsible for the key distortion from the classic octahedral structure type. The research team proposed that WTe2 owes its lack of saturation to the nearly perfect balance of electrons and electron holes, which are empty docks for traveling electrons. Because of its structure, WTe2 only exhibits magnetoresistance when the magnetic field is applied in a certain direction. This could be very useful in scanners, where multiple WTe2 devices could be used to detect the position of magnetic fields, Ali said.
“Aside from making devices from WTe2, the question to ask yourself as a scientist is: How can it be perfectly balanced, is there something more profound,” Cava said.