Bulletin of the American Physical Society
2011 Annual Meeting of the California-Nevada Section of the APS
Volume 56, Number 14
Friday–Saturday, November 11–12, 2011; Menlo Park, California
Session F3: Condensed Matter Physics III |
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Chair: Andreas Bill, California State University, Long Beach Room: Bldg 51 - Kavli Auditorium |
Saturday, November 12, 2011 1:00PM - 1:12PM |
F3.00001: Growth of Iridium on Ge(111) Studied by STM Marshall van Zijll, Cory Mullet, Bret Stenger, Emilie Huffman, Dylan Lovinger, William Mann, Shirley Chiang We have used scanning tunneling microscopy (STM) to characterize the growth of iridium onto Ge(111) as a function of coverage and annealing temperature. Ir was deposited onto the Ge(111) c(2x8) surface at different coverages less than 1ML, and then annealed to temperatures between 600K and 700K. The Ir forms islands which generally increase in size with increasing annealing temperature. In addition to island formation, other unique characteristics were observed, including the formation of Ir pathways connecting the islands. High resolution images have been obtained, which allow direct observation of the different phases. [Preview Abstract] |
Saturday, November 12, 2011 1:12PM - 1:24PM |
F3.00002: LEEM and STM studies of Ag on Ge (110) Bret Stenger, Cory Mullet, Marshall van Zijll, Emilie Huffman, Dylan Lovinger, Shirley Chiang The growth of Ag deposited on Ge(110) was studied with low energy electron microscopy (LEEM) and scanning tunneling microscopy (STM). The LEEM studies showed the formation of long one dimensional islands as Ag was deposited above 430\r{ }C. Island nucleation proceeded from defects in the Ge substrate. During deposition, the length of the islands increased while the width remained constant. The size and distribution of the islands was dependent on the substrate temperatures during deposition. At 480\r{ }C, islands were 100 nm wide and 1-20 $\mu $m long at 9 ML of coverage. At 530\r{ }C, islands were 200nm wide and 1-3 $\mu $m long at 9 ML of coverage. STM images showed that the islands were composed of Ag and that the surface regions between the islands exhibited a reconstruction which is characteristic of pure Ge. [Preview Abstract] |
Saturday, November 12, 2011 1:24PM - 1:36PM |
F3.00003: Phase competition in trisected superconducting dome Inna Vishik, M. Hashimoto, R.-H. He, W.-S. Lee, F. Schmitt, D.-H. Lu, R.G. Moore, C. Zhang, W. Meevasana, T. Sasagawa, S. Uchida, K. Fujita, S. Ishida, M. Ishikado, Y. Yoshida, H. Eisaki, Z. Hussain, T.P. Devereaux, Z.-X. Shen Angle resolved photoemission spectroscopy (ARPES) has been used to distinguish between quantum phases in the cuprates, particularly superconductivity and the pseudogap, based on their distinct spectroscopic phenomenology--temperature, doping, and momentum dependence. We present laser-ARPES experiments showing evidence for three distinct phases comprising the superconducting ground state in Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi-2212), accompanied by abrupt changes at p$\approx$0.076 and p$\approx$0.19 in the phenomenology of the superconducting gap near the bond-diagonal (nodal) direction. The latter likely marks the quantum critical point of the pseudogap, while the former may indicate a distinct competing phase at low doping. Temperature dependence studies of energy gaps provide further support for this characterization, and additionally present evidence that the pseudogap is not static below T$_c$. [Preview Abstract] |
Saturday, November 12, 2011 1:36PM - 1:48PM |
F3.00004: Phase transitions in dense nitrogen and carbon dioxide liquids Brian Boates, Stanimir Bonev The high-pressure phase diagrams of liquid nitrogen and carbon dioxide have been investigated using first-principles theory. Both liquids undergo rare first-order molecular-polymerization phase transitions at pressures comparable to their solid counterparts. Furthermore, both materials dissociate into metallic atomic fluids at high temperatures. The liquid regimes of their phase diagrams have been divided into several regions based on detailed analyses of changes in both structural and electronic properties for pressures and temperatures up to 200 GPa and 10,000 K, respectively. A comparison of the two liquid phase diagrams will be discussed to illustrate similarities and differences. Calculations of the shock Hugoniot are in excellent agreement with available experimental data. [Preview Abstract] |
Saturday, November 12, 2011 1:48PM - 2:00PM |
F3.00005: Boundary of Phase Co-existence in Docosahexaenoic Acid System CHai Lor, Linda S. Hirst Docosahexaenoic acid (DHA) is a highly polyunsaturated fatty acid (PUFA) that exhibits six double bonds in the hydrocarbon tail. It induces phase separation of the membrane into liquid order and liquid disorder in mixtures containing other lipids with more saturation and cholesterol. With the utilization of atomic force microscopy, phase co-existence is observed in lipid mixtures containing DHA on a single supported lipid bilayer. The boundary of phase co-existence with decreasing DHA concentration is explored. The elastic force, thickness, and roughness of the different phases are investigated. [Preview Abstract] |
Saturday, November 12, 2011 2:00PM - 2:12PM |
F3.00006: Third Sound in Superfluid Helium Films Adsorbed on Packed Multiwall Carbon Nanotubes Rebecca Roycroft, Emin Menachekanian, Gary Williams We are studying the propagation of third sound in thin $^4$He films adsorbed on multiwall carbon nanotubes. The nanotubes of 12.5-nm average diameter are lightly packed into an annular resonator, with a resistor bolometer used to detect temperature oscillations accompanying the waves. Standing-wave modes are excited by mechanical vibrations as well as heater drive, with FFT analysis allowing measurement of both the sound speed and dissipation. Initial experiments showed split harmonic frequencies, which have been resolved in a subsequent experiment using a different packing scheme. We observe the KT onset transition, and then at higher thicknesses capillary condensation becomes important. At 1.3 K we do not observe layering effects; lower-temperature measurements may be necessary to see these effects. [Preview Abstract] |
Saturday, November 12, 2011 2:12PM - 2:24PM |
F3.00007: Experimental Probe for Measurement of Thermodynamic Properties Nicholas Soliz, Ulises Urbina, Pei-Chun Ho Our measurement probe was designed and built to measure thermoelectric power (TEP, Seebeck coefficient) and thermal conductance. This measurement probe is custom made to fit in our cryocooler refrigerator for the temperature range from 11 K to 300 K. By using a small, 2k$\Omega $ resistive heater chip, and careful thermal isolation, we can apply a temperature gradient across our samples. We then monitor the raw trace of temperature and thermoelectric voltage as a function of time. Later, we extract the thermal conductance and the TEP by using the thermal equilibrium data. Automated data acquisition from room temperature to $\sim $12 K is obtained using LabVIEW software. Calibration of the measurement probe was performed on a Nickel sample and the measured TEP is compared to literature values to demonstrate the accuracy. The probe is being developed and calibrated for use in our investigation of TEP and thermal conductivity in single crystal samples of Pr$_{1-x}$Nd$_{x}$Os$_{4}$Sb$_{12}$ in the future. [Preview Abstract] |
Saturday, November 12, 2011 2:24PM - 2:36PM |
F3.00008: Hubbert's Peak: A Physicist's View Richard McDonald Oil and its by-products, as used in manufacturing, agriculture, and transportation, are the lifeblood of today's 7 billion-person population and our {\$}65T world economy. Despite this importance, estimates of future oil production seem dominated by wishful thinking rather than quantitative analysis. Better studies are needed. In 1956, Dr. M.King Hubbert proposed a theory of resource production and applied it successfully to predict peak U.S. oil production in 1970. Thus, the peak of oil production is referred to as ``Hubbert's Peak.'' Prof. Al Bartlett extended this work in publications and lectures on population and oil. Both Hubbert and Bartlett place peak world oil production at a similar time, essentially now. This paper extends this line of work to include analyses of individual countries, inclusion of multiple Gaussian peaks, and analysis of reserves data. While this is not strictly a predictive theory, we will demonstrate a ``closed'' story connecting production, oil-in-place, and reserves. This gives us the ``most likely'' estimate of future oil availability. Finally, we will comment on synthetic oil and the possibility of carbon-neutral synthetic oil for a sustainable future. [Preview Abstract] |
Saturday, November 12, 2011 2:36PM - 2:48PM |
F3.00009: A knot theory of physics, spacetime in co-dimension 2 Clifford Ellgen Attempts to describe particles as topological phenomena go back at least as far as Kelvin's conjecture that atoms are knots in the ether. A modern parallel is to ask whether the spacetime manifold of general relativity can be knotted and what properties those knots might have. However, if the manifold is everywhere Lorentzian, then a change of the topology of a spacelike slice of spacetime requires violation of causality. A consistent model emerges if we assume that the spacetime manifold is a 4-dimensional manifold embedded in a 6 dimensional Minkowski space and that each spacelike slice of the manifold has finite energy. A finite energy embedding allows the metric on the manifold to be degenerate on a set of measure zero, therefore the manifold may not be everywhere Lorentzian, which allows for certain types of topology change. An n-dimensional manifold embedded in an n+2-dimensional space can be knotted. We show that the possible knots on the spacetime manifold have properties corresponding to the known elementary particles. If we include the electromagnetic potential then we can use a simple Lagrangian to describe all of the forces including gravity. A simple extension of the assumptions produces quantum field theory. [Preview Abstract] |
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