3,739 research outputs found
SO(5) superconductor in a Zeeman magnetic field: Phase diagram and thermodynamic properties
In this paper we present calculations of the SO(5) quantum rotor theory of
high-T superconductivity in Zeeman magnetic field. We use the spherical
approach for five-component quantum rotors in three-dimensional lattice to
obtain formulas for critical lines, free energy, entropy and specific heat and
present temperature dependences of these quantities for different values of
magnetic field. Our results are in qualitative agreement with relevant
experiments on high-T cuprates.Comment: 4 pages, 2 figures, to appear in Phys. Rev. B, see http://prb.aps.or
Dependence of the superconducting critical temperature on the number of layers in homologous series of high-Tc cuprates
We study a model of -layer high-temperature cuprates of homologous series
like HgBa_2Ca_(n-1)Cu_nO_(2+2n+\delta) to explain the dependence of the
critical temperature Tc(n) on the number of Cu-O planes in the elementary
cell. Focusing on the description of the high-temperature superconducting
system in terms of the collective phase variables, we have considered a
semi-microscopic anisotropic three-dimensional vector XY model of stacked
copper-oxide layers with adjustable parameters representing microscopic
in-plane and out-of-plane phase stiffnesses. The model captures the layered
composition along c-axis of homologous series and goes beyond the
phenomenological Lawrence-Doniach model for layered superconductors.
Implementing the spherical closure relation for vector variables we have solved
the phase XY model exactly with the help of transfer matrix method and
calculated Tc(n) for arbitrary block size , elucidating the role of the
c-axis anisotropy and its influence on the critical temperature. Furthermore,
we accommodate inhomogeneous charge distribution among planes characterized by
the charge imbalance coefficient being the function of number of layers
. By making a physically justified assumption regarding the doping
dependence of the microscopic phase stiffnesses, we have calculated the values
of parameter as a function of block size in good agreement with the
nuclear magnetic resonance data of carrier distribution in multilayered high-Tc
cuprates.Comment: 15 pages, 10 figures. Submitted to Physical Review
Synthetic magnetic field effects on neutral bosonic condensates in quasi three-dimensional anisotropic layered structures
We discuss a system of dilute Bose gas confined in a layered structure of
stacked square lattices (slab geometry). A derived phase diagram reveals a
non-monotonic dependence of the ratio of tunneling to on-site repulsion on the
artificial magnetic field applied to the system. The effect is reduced when
more layers are added, which mimics a two- to quasi-three-dimensional geometry
crossover. Furthermore, we establish a correspondence between anisotropic
infinite (quasi three-dimensional) and isotropic finite (slab geometry) systems
that share exactly the same critical values, which can be an important clue for
choosing experimental setups that are less demanding, but still leading to the
identical results. Finally, we show that the properties of the ideal Bose gas
in a three-dimensional optical lattice can be closely mimicked by finite (slab)
systems, when the number of two-dimensional layers is larger than ten for
isotropic interactions or even less, when the layers are weakly coupled.Comment: http://pra.aps.org/abstract/PRA/v83/i2/e02360
Collective patterns arising out of spatio-temporal chaos
We present a simple mathematical model in which a time averaged pattern
emerges out of spatio-temporal chaos as a result of the collective action of
chaotic fluctuations. Our evolution equation possesses spatial translational
symmetry under a periodic boundary condition. Thus the spatial inhomogeneity of
the statistical state arises through a spontaneous symmetry breaking. The
transition from a state of homogeneous spatio-temporal chaos to one exhibiting
spatial order is explained by introducing a collective viscosity which relates
the averaged pattern with a correlation of the fluctuations.Comment: 11 pages (Revtex) + 5 figures (postscript
A 75-110 GHz CP-FTmmW spectrometer for reaction dynamics and kinetics studies
A BrightSpec chirped-pulsed Fourier transform millimeter-wave spectrometer operating in the 75--110 GHz spectral region has been installed at Argonne National Laboratory. The instrument has been tailored for chemical reaction dynamics and kinetics studies, and the arrangement allows for easy alternation between a room temperature flow cell and a supersonic expansion. The molecular beam is equipped with a pyrolysis nozzle for monitoring reaction products. Benchmark measurements in the flow cell will be presented along with early pyrolysis observations
Plasma Source of Charged Particles Based on a Discharge in Crossed E*H Fields with an Increased Perveance
This paper presents a design layout of the plasma source of charged particles in crossed E*H fields with high perveance. Its electrode structure is given, describes a source operation mechanism, the prospects for further development of a high-perveance source for industrial applications based on it are shown
- …