52,507 research outputs found
Spinless Calogero-Sutherland model with twisted boundary condition
In this work, the spinless Calogero-Sutherland model with twisted boundary
condition is studied. The ground state wavefunctions, the ground state
energies, the full energy spectrum are provided in details.Comment: preprint of ETH-L, appearing in recent PR
Thermodynamic and Tunneling Density of States of the Integer Quantum Hall Critical State
We examine the long wave length limit of the self-consistent Hartree-Fock
approximation irreducible static density-density response function by
evaluating the charge induced by an external charge. Our results are consistent
with the compressibility sum rule and inconsistent with earlier work that did
not account for consistency between the exchange-local-field and the disorder
potential. We conclude that the thermodynamic density of states is finite, in
spite of the vanishing tunneling density of states at the critical energy of
the integer quantum Hall transition.Comment: 5 pages, 4 figures, minor revisions, published versio
Intrinsic Room Temperature Ferromagnetism in Boron-doped ZnO
We report room temperature ferromagnetism in boron-doped ZnO both
experimentally and theoretically. The single phase Zn1-xBxO films deposited
under high oxygen pressure by pulsed-laser deposition show ferromagnetic
behavior at room temperature. The saturation magnetization increases
monotonously from 0 to 1.5 emu/cm3 with the increasing of B component x from 0
to 6.8%. The first-principles calculations based on density functional theory
demonstrate that the ferromagnetism in B-doped ZnO originates from the induced
magnetic moments of oxygen atoms in the nearest neighbor sites to the B-Zn
vacancy pair. The calculated total magnetic moment increasing tendency with B
component is well consistent with experiments.Comment: 16 pages, 1 table, 4 figures
Multi-Band Exotic Superconductivity in the New Superconductor Bi4O4S3
Resistivity, Hall effect and magnetization have been investigated on the new
superconductor Bi4O4S3. A weak insulating behavior has been induced in the
normal state when the superconductivity is suppressed. Hall effect measurements
illustrate clearly a multiband feature dominated by electron charge carriers,
which is further supported by the magnetoresistance data. Interestingly, a kink
appears on the temperature dependence of resistivity at about 4 K at all high
magnetic fields when the bulk superconductivity is completely suppressed. This
kink can be well traced back to the upper critical field Hc2(T) in the low
field region, and is explained as the possible evidence of residual Cooper
pairs on the one dimensional chains.Comment: 5 pages, 5 figure
Lanthanum distribution and dielectric properties of intergrowth Bi₅ˍₓLaₓTiNbWO₁₅ ferroelectrics
Bi₅ˍₓLaₓTiNbWO₁₅ (x=0–1.50)ceramics prepared by conventional solid-state reaction were studied using x-ray diffraction(XRD),dielectric spectroscopy and Raman scattering techniques. The XRD analysis implied that single-phase intergrowth bismuth layered perovskite structure was obtained for all the samples and when x=0.75, the Bi³⁺ in (Bi₂O₂)²⁺ layer begins to be substituted by La³⁺. The dielectric spectra showed that, when Bi³⁺ in (Bi₂O₂)²⁺ is substituted, the Curie temperature becomes diffusive and the dielectricpermittivity at room temperature is increased in a wide frequency range. Especially when x=1.50, the dielectricpermittivity reaches its maximum of 270, nearly two times larger than that of the La3+ undoped sample. The Raman scattering experiments evidenced further that Bi³⁺ in (Bi₂O₂)²⁺ is substituted when x⩾0.75 and revealed the orthorhombic distortion of the octahedra is responsible for the increase of the dielectricpermittivity at x⩾1.25.This work was supported by the Ministry of Science and
Technology of China through 973-Project under Grant No.
2002CB613307
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