2,996 research outputs found
Electric Dipole Moments of Neutron-Odd Nuclei
The electric dipole moments (EDMs) of neutron-odd nuclei with even protons
are systematically evaluated. We first derive the relation between the EDM and
the magnetic moment operators by making use of the core polarization scheme.
This relation enables us to calculate the EDM of neutron-odd nuclei without any
free parameters. From this calculation, one may find the best atomic system
suitable for future EDM experiments.Comment: 4 page
Nature of Chemisorption on Titanium Carbide and Nitride
Extensive density-functional calculations are performed to understand atomic
chemisorption on the TiC(111) and TiN(111) surfaces, in particular the
calculated pyramid-shaped trends in the adsorption energies for second- and
third-period adatoms. Our previously proposed concerted-coupling model for
chemisorption on TiC(111) is tested against new results for adsorption on
TiN(111) and found to apply on this surface as well, thus reflecting both
similarities and differences in electronic structure between the two compounds.Comment: 7 pages, 4 figures, conference proceeding presented at IWSP-2005
(Polanica Zdoj, Poland, 2005), submitted to Surf. Sci. (2005
Thermally induced biosynthesis of 2'-O-methylguanosine in tRNA from an extreme thermophile, Thermus thermophilus HB27.
Spin-filter tunnel junction with matched Fermi surfaces
Efficient injection of spin-polarized current into a semiconductor is a basic
prerequisite for building semiconductor-based spintronic devices. Here, we use
inelastic electron tunneling spectroscopy to show that the efficiency of
spin-filter-type spin injectors is limited by spin scattering of the tunneling
electrons. By matching the Fermi-surface shapes of the current injection source
and target electrode material, spin injection efficiency can be significantly
increased in epitaxial ferromagnetic insulator tunnel junctions. Our results
demonstrate that not only structural but also Fermi-surface matching is
important to suppress scattering processes in spintronic devices.Comment: 5 pages, 4 figure
In-situ photoemission study of Pr_{1-x}Ca_xMnO_3 epitaxial thin films with suppressed charge fluctuations
We have performed an {\it in-situ} photoemission study of Pr_{1-x}Ca_xMnO_3
(PCMO) thin films grown on LaAlO_3 (001) substrates and observed the effect of
epitaxial strain on the electronic structure. We found that the chemical
potential shifted monotonically with doping, unlike bulk PCMO, implying the
disappearance of incommensurate charge fluctuations of bulk PCMO. In the
valence-band spectra, we found a doping-induced energy shift toward the Fermi
level (E_F) but there was no spectral weight transfer, which was observed in
bulk PCMO. The gap at E_F was clearly seen in the experimental band dispersions
determined by angle-resolved photoemission spectroscopy and could not be
explained by the metallic band structure of the C-type antiferromagnetic state,
probably due to localization of electrons along the ferromagnetic chain
direction or due to another type of spin-orbital ordering.Comment: 5 pages, 4 figure
Trends in Atomic Adsorption on Titanium Carbide and Nitride
Extensive density-functional calculations on atomic chemisorption of H, B, C,
N, O, F, Al, Si, P, S, and Cl on the polar TiC(111) and TiN(111) yield similar
adsorption trends for the two surfaces: (i) pyramid-like adsorption-energy
trends along the adatom periods; (ii) strongest adsorption for O, C, N, S, and
F; (iii) large adsorption variety; (iv) record-high adsorption energy for O
(8.4-8.8 eV). However, a stronger adsorption on TiN is found for elements on
the left of the periodic table and on TiC for elements on the right. The
results support that a concerted-coupling model, proposed for chemisorption on
TiC, applies also to TiN.Comment: 5 pages, 4 figures, 2 tables, conference proceeding presented at
ECOSS-23 (Berlin, 2005), submitted to Surf. Sci. (2005
Dynamical Structure Factor in Cu Benzoate and other spin-1/2 antiferromagnetic chains
Recent experiments of the quasi-one-dimensional spin-1/2 antiferromagnet
Copper Benzoate established the existence of a magnetic field induced gap. The
observed neutron scattering intensity exhibits resolution limited peaks at both
the antiferromagnetic wave number and at incommensurate wave numbers related to
the applied magnetic field. We determine the ratio of spectral weights of these
peaks within the framework of a low-energy effective field theory description
of the problem.Comment: 5 pages, 3figure
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