Bulletin of the American Physical Society
2015 Annual Spring Meeting of the APS Ohio-Region Section
Volume 60, Number 3
Friday–Saturday, March 27–28, 2015; Kent, Ohio
Session B5: Condensed Matter I |
Hide Abstracts |
Chair: Almut Schroeder, Kent State University Room: KSU Student Center 317 |
Friday, March 27, 2015 3:00PM - 3:15PM |
B5.00001: The RKKY Interaction in a Polarized Electron Gas Christopher Porter The RKKY interaction is a well-known itinerant interaction that can account for long-range magnetic interaction, and does not require overall polarization of the electron gas through which the interaction occurs. In fact, very few authors have considered the effects of the polarization of the electron gas. We present analytical and numerical evidence that the polarization of the electron gas can play an important role in the coupling of spins in a lattice. We use classical Monte Carlo simulations of spin relaxation with annealing to identify ferromagnetic and antiferromagnetic states. Such calculations are relevant for disordered distributions of large-spin ions in a nonmagnetic lattice such as the heavy doping of Mn in GaAs diluted magnetic semiconductors. [Preview Abstract] |
Friday, March 27, 2015 3:15PM - 3:30PM |
B5.00002: Dipolar 2D and Quasi-2D Bosons with Non-zero Dipole Tilt Angle Pengtao Shen, Khandker Quader We study properties of dipolar bosons both in the cases of 2D and quasi-2D (tightly confined in trap in a z-direction), with dipoles oriented at an angle to the direction perpendicular to the 2D plane. Starting from time-dependent Gross-Pitaevski equations, and the resulting Bogoliubov-de Gennes equations, we calculate the excitation spectrum of the Bose-Einstein condensate, and map out resulting phase diagrams as functions of tilt angle, interaction strength and density. In pure 2D, we find the development of maxon-roton behavior leading to roton instabilities at large densities for small tilt angles, and at low densities for large tilt angles. The behavior is anisotropic in k-space; accordingly the roton instabilities occur in the k$_y$ direction, suggestive of inhomogeneity and stripe phase, with density mode becoming soft in the y direction. This is reflected in the behavior of our liquid structure function. We also find our calculated condensate depletion rates to vary appreciably with title angle. We compare our pure 2D and quasi-2D results, and discuss similarities and differences. [Preview Abstract] |
Friday, March 27, 2015 3:30PM - 3:45PM |
B5.00003: Multi-band nature and anisotropy of heavily doped Ba$_{1-x}$K$_x$Fe$_2$As$_2$ Shuai Zhang, Xinyi Huang, Yogesh Singh, Carmen Almasan We have carried out a detailed study on single crystals of Ba$_{\mathrm{1-x}}$K$_{\mathrm{x}}$Fe$_{2}$As$_{2}$ with doping level x very close to 1, Ba$_{0.05}$K$_{0.95}$Fe$_{2}$As$_{2}$ with T$_{\mathrm{c}} = $ 6.6 K, which exceeds the Lifshitz transition around x $=$ 0.9. The heat capacity C(T) shows a relatively large nodeless energy gap of 1.93 k$_{\mathrm{B}}$T$_{\mathrm{c}}$ based on a three-band BCS model analysis, which suggests that the SC state with the biggest gap value shows a fully opened s-wave superconducting characteristic and a possible nodal gap that shows a rather small gap value. A full H-T phase diagram has been determined by measuring C(T) and resistivity under fields in ab plane and c direction. Angle-resolved resistivity measurements at low temperatures were used to probe the angular dependence of upper critical field, showing an anisotropy well explained by using the Ginzburg-Landau theory. [Preview Abstract] |
Friday, March 27, 2015 3:45PM - 4:00PM |
B5.00004: Enhanced quasiparticle scattering and scaling of Ba(Fe$_{\mathrm{1-x}}$Co$_{\mathrm{x}})_{2}$As$_{2}$ flux-flow resistivity under the superconducting dome Xinyi Huang, Derek Haney, Yogesh Singh, Shuai Zhang, Hai-Hu Wen, Tao Hu, Maxim Dzero, Carmen Almasan We utilize the current-voltage (I-V) technique to probe the quasiparticle scattering in the mixed state of Ba(Fe$_{\mathrm{1-x}}$Co$_{\mathrm{x}})_{\mathrm{2}}$As$_{\mathrm{2}}$~crystals. Analysis of the free-flux-flow resistivity within the vortices shows a sharp increase in the quasiparticle scattering with decreasing temperature and applied field. This abrupt flux-flow resistivity behavior is attributed to the presence of critical spin fluctuations inside the vortex core. The fluctuations are strongest for x $=$ 0.06, and is suppressed on either side of this doping. For each doping measured, at different temperatures and applied fields, the vortex dissipation curves scale and show an exponential relationship. We will discuss the physics behind the observed scaling behavior. [Preview Abstract] |
(Author Not Attending)
|
B5.00005: Resistivity and magnetoresistance studies of quantum critical alloy Ce$_{0.93}$Yb$_{0.07}$CoIn$_{5}$ under pressure Y.P. Singh, D.J. Haney, X.Y. Huang, B.D. White, M.B. Maple, M. Dzero, C.C. Almasan We performed experimental and theoretical studies of the effect of pressure on the heavy fermion quantum critical alloy Ce$_{0.93}$Yb$_{0.07}$CoIn$_{5}$. Our resistivity measurement shows that Ce$_{\mathrm{1-x}}$Yb$_{\mathrm{x}}$CoIn$_{5}$ system exhibits non-Fermi liquid behavior with two distinct contributions to resistivity (linear-in-T and square-root-in-T). Resistivity measurements under pressure show that linear in T resistivity is governed by heavy/large Fermi surface and is suppressed with pressure. Quantum fluctuations with pressure are also shown to be suppressed in Ce$_{0.93}$Yb$_{0.07}$CoIn$_{5}$. The square-root-in-T dependence originates from two different physics: (i) the~$\surd $T dependence just above T$_{\mathrm{c}}$ is suppressed with the application of pressure, and is a result of superconducting fluctuations; (ii) the higher temperature $\surd $T contribution to resistivity remains insensitive to pressure, indicating that the scattering processes in this T range are governed by the scattering of light electrons from the small Fermi surface. We further demonstrate that the growth of the coherence temperature with pressure, as well as the decrease of the residual resistivity, can be accurately described by employing the coherent potential approximation for a disordered Kondo lattice. [Preview Abstract] |
Friday, March 27, 2015 4:15PM - 4:30PM |
B5.00006: Hot Wire Probe to Study Charge Carriers Type in Individual Sb-doped ZnO Micro-Wires Nada Masmali, Lei Kerr, Khalid Eid We investigated the electric transport properties of Sb-doped ZnO Nano/microwires. ZnO:Sb wires were fabricated by thermal evaporation at 900 $^{\circ}$C in an alumina crucible. Scanning electron microscopy (SEM) was used to study the surface morphology. The elemental components were determined using X-ray energy dispersive spectroscopy (EDX). The electrical properties of Sb doped ZnO were studied using thermoelectric effect measurements. The hot probe technique is extremely simple and gives a reliable measurement of the charge carrier type in a wire, where the standard Hall probe technique is difficult to implement. The hot-wire probe studies, that were used to investigate the type of conductivity in ZnO wires, show an n-type conduction. [Preview Abstract] |
Friday, March 27, 2015 4:30PM - 4:45PM |
B5.00007: Synthesis and Characterization of Indium Antimonide Nanoparticles (NPs) using Inert Gas Condensation Process Sneha Pandya, Martin Kordesch Nanoparticles (NPs) of Indium Antimonide (InSb), varying from 10nm to 200nm in size, were synthesized using a vapor phase synthesis technique known as Inert Gas Condensation (IGC) process. These NPs were directly deposited over 1 inch-square (111) p-type Silicon (Si) wafer, glass cover slip and Sodium Chloride (NaCl) substrates. The Wide-Angle X-ray Scattering spectra obtained for these NPs showed (111) and (220) diffraction peaks and revealed the crystalline behavior of these NPs exhibiting a cubic symmetry. The 1:1 composition ratio of In:Sb was confirmed by the Energy Dispersive X-Ray Spectroscopy studies. Raman spectra of these NPs exhibited a peak at 186.7cm$^{\mathrm{1}}$, which corresponds to the LO modes of phonon vibration in InSb. The morphological and structural characterization of these NPs will be carried out using a High-Resolution TEM and XRD. X-ray peak broadening analysis will be used to evaluate the crystalline sizes and lattice strain by the Williamson-Hall (W-H) analysis. NPs will be size selected during the synthesis process and their size dependent band gap, measured using Fourier Transform Infrared (FTIR) spectroscopy, will be presented. Wavelength dependent photo-responsivity will be measured and the corresponding results will be discussed [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700