47,724 research outputs found
Superfluid response in electron-doped cuprate superconductors
We propose a weakly coupled two-band model with pairing
symmetry to account for the anomalous temperature dependence of superfluid
density in electron-doped cuprate superconductors. This model gives a
unified explanation to the presence of a upward curvature in near
and a weak temperature dependence of in low temperatures. Our
work resolves a discrepancy in the interpretation of different experimental
measurements and suggests that the pairing in electron-doped cuprates has
predominately symmetry in the whole doping range.Comment: 4 pages, 3 figures, title changed and references adde
Optimizing Hartree-Fock orbitals by the density-matrix renormalization group
We have proposed a density-matrix renormalization group (DMRG) scheme to
optimize the one-electron basis states of molecules. It improves significantly
the accuracy and efficiency of the DMRG in the study of quantum chemistry or
other many-fermion system with nonlocal interactions. For a water molecule, we
find that the ground state energy obtained by the DMRG with only 61 optimized
orbitals already reaches the accuracy of best quantum Monte Carlo calculation
with 92 orbitals.Comment: published version, 4 pages, 4 figure
Comment on "Time-Dependent Density-Matrix Renormalization Group: A Systematic Method for the Study of Quantum Many-Body Out-of- Equilibrium Systems"
In a recent Letter [Phys. Rev. Lett. 88, 256403(2002), cond-mat/0109158]
Cazalilla and Marston proposed a time-dependent density- matrix renormalization
group (TdDMRG) algorithm for the accurate evaluation of out-of-equilibrium
properties of quantum many-body systems. For a point contact junction between
two Luttinger liquids, a current oscillation develops after initial transient
in the insulating regime. Here we would like to point out that (a) the observed
oscillation is an artifact of the method; (b) the TdDMRG can be significantly
improved by incorporating the non-equilibrium evolution of the goundstate into
the density matrix.Comment: 1 page, 2 figure
Interpolation function of the genocchi type polynomials
The main purpose of this paper is to construct not only generating functions
of the new approach Genocchi type numbers and polynomials but also
interpolation function of these numbers and polynomials which are related to a,
b, c arbitrary positive real parameters. We prove multiplication theorem of
these polynomials. Furthermore, we give some identities and applications
associated with these numbers, polynomials and their interpolation functions.Comment: 14 page
In-plane ferromagnetism in charge-ordering
The magnetic and transport properties are systematically studied on the
single crystal with charge ordering and divergency in
resistivity below 50 K. A long-range ferromagnetic ordering is observed in
susceptibility below 20 K with the magnetic field parallel to Co-O plane, while
a negligible behavior is observed with the field perpendicular to the Co-O
plane. It definitely gives a direct evidence for the existence of in-plane
ferromagnetism below 20 K. The observed magnetoresistance (MR) of 30 % at the
field of 6 T at low temperatures indicates an unexpectedly strong spin-charge
coupling in triangle lattice systems.Comment: 4 pages, 5 figure
Thermodynamic properties of tetrameric bond-alternating spin chains
Thermodynamic properties of a tetrameric bond-alternating Heisenberg spin
chain with ferromagnetic-ferromagnetic-antiferromagnetic-antiferromagnetic
exchange interactions are studied using the transfer-matrix renormalization
group and compared to experimental measurements. The temperature dependence of
the uniform susceptibility exhibits typical ferrimagnetic features. Both the
uniform and staggered magnetic susceptibilities diverge in the limit ,
indicating that the ground state has both ferromagnetic and antiferromagnetic
long-range orders. A double-peak structure appears in the temperature
dependence of the specific heat. Our numerical calculation gives a good account
for the temperature and field dependence of the susceptibility, the
magnetization, and the specific heat for Cu(3-Clpy)(N)
(3-Clpy=3-Chloroyridine).Comment: 8 pages, 12 figures; Replaced with final version accepted in Phys.
Rev.
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