3,866 research outputs found
Origin of the Heavy Fermion Behavior in Ca_{2-x}Sr_{x}RuO_{4}: Roles of Coulomb Interaction and the Rotation of RuO_{6} octahedra
We study the electronic states for Ca_{2-x}Sr_{x}RuO_{4} in within the Gutzwiller approximation (GA) on the basis of the three-orbital
Hubbard model for the Ru t_{2g} orbitals. The main effects of the Ca
substitution are taken account as the changes of the hybridizations
between the Ru 4d and O 2p orbitals. Using the numerical minimization of the
energy obtained in the GA, we obtain the renormalization factor (RF) of the
kinetic energy and total RF, which estimates the inverse of the mass
enhancement, for three cases with the effective models of x=2 and 0.5 and a
special model. We find that the inverse of the total RF becomes the largest for
the case of x=0.5, and that the van Hove singularity, which is located on
(below) the Fermi level for the special model (the effective model of x=0.5),
plays a secondary role in enhancing the effective mass. Our calculation
suggests that the heavy fermion behavior around x=0.5 comes from the
cooperative effects between moderately strong Coulomb interaction compared to
the total bandwidth and the modification of the electronic structures due to
the rotation of RuO_{6} octahedra (i.e., the variation of the
hybridizations and the downward shift for the orbital). We propose
that moderately strong electron correlation and the orbital-dependent
modifications of the electronic structures due to the lattice distortions play
important roles in the electronic states for Ca_{2-x}Sr_{x}RuO_{4}.Comment: 16 pages, 13 figures, 1 table, accepted for publication in Physical
Review B; added the discussions both about the validity of the present
treatment and about Hund's metal in this allo
Media used for culture of and distribution of stocks
Media used for culture of and distribution of stock
Preservation of amycelial-aconidial Neurospora cultures using anhydrous silica gel
Preservation of amycelial-aconidial Neurospora cultures using anhydrous silica ge
Preservation of Neurospora stock cultures with anhydrous silica gel
Preservation of Neurospora stock cultures with anhydrous silica ge
Ferromagnetic fluctuation and possible triplet superconductivity in Na_xCoO_2*yH_2O: Fluctuation-exchange study of multi-orbital Hubbard model
Spin and charge fluctuations and superconductivity in a recently discovered
superconductor Na_xCoO_2*yH_2O are studied based on a multi-orbital Hubbard
model. Tight-binding parameters are determined to reproduce the LDA band
dispersions with the Fermi surface, which consist of a large cylindrical one
around the Gamma-point and six hole pockets near the K-points. By applying the
fluctuation-exchange (FLEX) approximation, we show that the Hund's-rule
coupling between the Co t2g orbitals causes ferromagnetic (FM) spin
fluctuation. Triplet f_{y(y^2-3x^2)}-wave and p-wave pairings are favored by
this FM fluctuation on the hole-pocket band. We propose that, in
Na_xCoO_2*yH_2O, the Co t2g orbitals and inter-orbital Hund's-rule coupling
play important roles on the triplet pairing, and this compound can be a first
example of the triplet superconductor in which the orbital degrees of freedom
play substantial roles.Comment: 5 pages, 3 figure
A method for scoring [mi-1] and [mi-1]f in growth tubes
Scoring [mi-1] and [mi-1]f in growth tube
Effect of nitrogen source and pH on the growth of a glutamine requiring strain (glm)
Effect of nitrogen source and pH on the growth of a glutamine requiring strain (glm
Growth conditions for [abn-1] and [abn-2] in liquid media
Growth conditions for [abn-1] and [abn-2] in liquid medi
Experimental demonstration of four-party quantum secret sharing
Secret sharing is a multiparty cryptographic task in which some secret
information is splitted into several pieces which are distributed among the
participants such that only an authorized set of participants can reconstruct
the original secret. Similar to quantum key distribution, in quantum secret
sharing, the secrecy of the shared information relies not on computational
assumptions, but on laws of quantum physics. Here, we present an experimental
demonstration of four-party quantum secret sharing via the resource of
four-photon entanglement
Variational Study of the Spin-Gap Phase of the One-Dimensional t-J Model
We propose a correlated spin-singlet-pairs wave function to describe the
spin-gap phase of the one-dimensional model at low density. Adding a
Jastrow factor with a variational parameter, , first introduced by
Hellberg and Mele, is shown to correctly describe the long-range behavior
expected for the Luther-Emery phase. Using the variational Monte Carlo method
we establish a relation between and the Luttinger exponent ,
.Comment: 4 pages (LaTex), 3 figures attache
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