Bulletin of the American Physical Society
2005 72nd Annual Meeting of the Southeastern Section of the APS
Thursday–Saturday, November 10–12, 2005; Gainesville, FL
Session CD: Condensed Matter I: Theory and Low Temperature |
Hide Abstracts |
Chair: Mark Meisel, University of Florida Room: Hilton Hickory |
Thursday, November 10, 2005 10:45AM - 10:57AM |
CD.00001: The Bose-Fermi Kondo model and heavy-fermion quantum criticality Matthew T. Glossop, Kevin Ingersent Bose-Fermi Kondo models (BFKMs), describing a local magnetic
moment coupled to a conduction band
and a dissipative bosonic bath, are of current interest in
connection with non-Fermi-liquid behavior of quantum critical
heavy-fermions [1].
The latter are believed to be well-described by the Kondo lattice
model, which maps onto a self-consistent BFKM within the extended
dynamical mean-field theory (EDMFT) framework [2]. With a view
to providing conclusive solutions of the KLM we have extended the
numerical renormalization group (NRG) approach to tackle
Bose-Fermi quantum impurity problems [3]. Here we treat the BFKM
with Ising-symmetry couplings to a bosonic bath described by
spectral function $\eta(\omega)\propto\omega^s$.
The method gives an excellent account of the critical properties
of the model, which we show belongs to the same universality
class as the spin boson model. For sub-Ohmic bath exponents
$0 |
Thursday, November 10, 2005 10:57AM - 11:09AM |
CD.00002: Hydrodynamic modes and the density-density correlation function of a supersolid Chi-Deuk Yoo, Alan Dorsey Recently Kim and Chan have observed the Non-classical Rotational Inertia of solid $^4$He in Vycor glass [1] and in bulk [2] below around 200mK, and have interpreted their results as the onset of a supersolid phase [3]. As an alternative to detecting the supersolid phase, it is interesting to see whether a supersolid has a second sound mode analogous to a superfluid. We have derived hydrodynamics for a supersolid, and calculated the hydrodynamic mode frequencies for an isotropic supersolid, obtaining a longitudinal second sound mode. In addition, we have calculated the density-density correlation function in linear response theory, and find that one of the central Rayleigh peaks of a normal solid splits into two Brillouin peaks at $\omega=\pm c_2 q$ in supersolid phase, where $c_2$ is the second sound speed of a supersolid. This behavior could be reveiled in a light scattering experiment from the solid.\newline \newline [1] E. Kim and M. H. W. Chan, Nature {\bf 427}, 225 (2004). \newline [2] E. Kim and M. H. W. Chan, Science {\bf 305}, 1941 (2004). \newline [3] A. J. Leggett, Phys. Rev. Lett. {\bf 25}, 1543 (1970). [Preview Abstract] |
Thursday, November 10, 2005 11:09AM - 11:21AM |
CD.00003: Precursors of 1D behavior for $D>1$: evolution of the non-analytic correction to the Fermi-liquid behavior Ronojoy Saha, Dmitrii Maslov The Fermi-liquid forms of the specific heat ($C(T)$) and static spin susceptibility ($\chi_s$) acquire universal non-analytic corrections[1] and the degree of non-analyticity increase inversely with the dimensionality. This predicts that the strongest non-analyticity in the specific heat should be found in 1D; however, bosonization shows that the $C(T)$ is analytic in 1D. We resolve this paradox by showing that the general argument, for non-analyticity in $D>1$ at the second order in the interaction, breaks down in 1D due to a subtle cancellation and the non-analytic $T\ln T$ term in the specific heat in 1D occurs at the \emph{third} order for electrons with \emph{spin}. We obtain the same result by considering the RG flow of the marginally irrelevant operator in the sine-Gordon theory. For spinless electrons, the non-analyticities in the particle-particle and particle-hole channels cancel out and the resulting $C(T)$ is linear in $T$. The singularity in the particle-hole channel causes non-analyticity in the spin susceptibility $\chi_s \propto \ln \max \{|Q|,|H|,T\}$ present at the second order. [1] A.V. Chubukov and D.L. Maslov, Phys. Rev. B 68, 155113 (2003). [Preview Abstract] |
Thursday, November 10, 2005 11:21AM - 11:33AM |
CD.00004: Shielded Superconducting Linear Motor for Towed-Grid Studies of Quantum Turbulence Shu-chen Liu, Yihui Zhou, Gary G. Ihas The purpose of the ongoing low temperature quantum turbulence research is to compare experimental data with existing theoretical results. Both should be carefully produced under the same conditions, i.e., isotropic homogeneous turbulence. In our planned experiment, this requirement would be met by towing a grid through a channel of superfluid helium at 20 mK. A grid motion of 1 cm at a nearly constant speed of 1 m/s is required. To avoid heating due to the motive force driving the grid, a magnetically shielded superconducting linear motor is proposed. The grid is attached to the end of a light insulating rod which has two niobium cylinders fastened to it and about 15 mm apart. This part of the rod is inside a superconducting solenoid which, when driven with the properly shaped pulse current, accelerates the rod (and grid) over 1 mm, moves the rod and grid at constant speed for 10 mm, and then decelerates it over 1 mm. Simulation results demonstrate that the voltages and currents required are quite reasonable. The simulation and control program is written in LabView with embedded C compiler. Using the simulator, various designs of solenoid, with and without shielding, may be easily investigated. The most promising designs along with the experimental testing results will be presented. [Preview Abstract] |
Thursday, November 10, 2005 11:33AM - 11:45AM |
CD.00005: Sub-millimeter Size Sensors for Measurements in Cryogenic Turbulence Yihui Zhou, Vadim F. Mitin, Shu-chen Liu, Isaac Luria, Mario Padron, Ridvan Adjimambetov, Gary G. Ihas Classical turbulence research is advancing by utilizing MEMS temperature and pressure fluctuation sensor technology. Turbulence research at cryogenic temperatures has many advantages over the classical approach, such as extreme stability of control parameters and very high Reynolds numbers in small apparatus. However, changes in material properties from room temperature to 1 K (and below) make most sensors unusable at low temperature. A new type of thermistor, incorporating a Ge-film deposited on a GaAs substrate, has been designed. It provides high sensitivity in the range of 20 mK to 5 K. In this paper, the design and characteristics of these sensors is discussed, and experimental data from three thermistors is presented. Progress on a miniature pressure transducer is also described. [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