11,249 research outputs found

### Novel Electronic State and Superconductivity in the Electron-Doped High-Tc T'-Superconductors

In this review article, we show our recent results relating to the undoped
(Ce-free) superconductivity in the electron-doped high-Tc cuprates with the
so-called T' structure. For an introduction, we briefly mention the
characteristics of the electron-doped T'-cuprates, including the reduction
annealing, conventional phase diagram and undoped superconductivity. Then, our
transport and magnetic results and results relating to the superconducting
pairing symmetry of the undoped and underdoped T'-cuprates are shown.
Collaborating spectroscopic and nuclear magnetic resonance results are also
shown briefly. It has been found that, through the reduction annealing, a
strongly localized state of carriers accompanied by an antiferromagnetic
pseudogap in the as-grown samples changes to a metallic and superconducting
state with a short-range magnetic order in the reduced superconducting samples.
The formation of the short-range magnetic order due to a very small amount of
excess oxygen in the reduced superconducting samples suggests that the
T'-cuprates exhibiting the undoped superconductivity in the parent compounds
are regarded as strongly correlated electron systems, as well as the hole-doped
high-Tc cuprates. We show our proposed electronic structure model to understand
the undoped superconductivity. Finally, unsolved future issues of the
T'-cuprates are discussed.Comment: 13 pages, 8 figure

### Magnetic-field effects on the charge-spin stripe order in La-214 high-Tc cuprates

Magnetic-field effects on the charge-spin stripe order in La-214 high-Tc
cuprates have been investigated from measurements of the in-plane
electrical-resistivity, Rho_ab_. In La_2-x_Ba_x_CuO_4_ with x=0.10 and
La_2-x_Sr_x_CuO_4_ with x=0.115 where the incommensurate charge peaks are weak
and unobservable in zero field in elastic neutron-scattering measurements,
respectively, the normal-state value of Rho_ab_ at low temperatures markedly
increases with increasing field up to 27 T. For La_2-x_Ba_x_CuO_4_ with x=0.11
and Zn-substituted La_2-x_Sr_x_Cu_1-y_Zn_y_O_4_ with x=0.115 and y=0.02 where
the charge stripe order is fairly stabilized in zero field, on the other hand,
the increase in Rho_ab_ with increasing field is negligibly small. In
conclusion, when the charge-spin stripe order is not fully stable in zero
field, magnetic field operates to stabilize the charge-spin stripe order. The
value of Rho_ab_ increases with increasing field depending on the stability of
the charge stripe order.Comment: 4 pages, 2 figures, Proceedings of Yamada Conference LX on Research
in High Magnetic Fields (RHMF2006) (Satellite of ICM2006

### Chemisorption and reactions on clusters of nickel atoms

The nucleation and growth of metallic clusters on a substantially amorphous substrate are discussed with emphasis on the geometrical and electronic structure of the clusters. Several clusters of different symmetry containing five to nine nickel atoms were studied. It was found that the energy range of primary d-like states is not significantly different from the width of the d-band states in nickel metal, as long as the interatomic distance is comparable to that in the bulk metal. The approach of one or more molecules to the cluster is examined using at the hydrogenation of acetylene and the dehydrogenation of ethylene as examples

### Numerical Study of Velocity Statistics in Steady Counterflow Quantum Turbulence

We investigate the velocity statistics by calculating the Biot--Savart
velocity induced by vortex filaments in steady counterflow turbulence
investigated in a previous study [Phys. Rev. B {\bf 81}, 104511 (2010)]. The
probability density function (PDF) obeys a Gaussian distribution in the
low-velocity region and a power-law distribution $v^{-3}$ in the high-velocity
region. This transition between the two distributions occur at the velocity
characterized by the mean inter-vortex distance. Counterflow turbulence causes
anisotropy of the vortex tangle, which leads to a difference in the PDF for the
velocities perpendicular to and parallel to the counterflow.Comment: 4 pages, 7 figure

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