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Low temperature behavior of the heavy Fermion Ce3Co4Sn13
The compound Ce3Co4Sn13 is an extremely heavy cubic heavy fermion system with
a low temperature electronic specific heat of order ~4 J/mol-K2. If the
compound is nonmagnetic, it would be one of the heaviest nonmagnetic Ce-based
heavy fermions reported to date and therefore would be expected to lie
extremely close to a quantum critical point. However, a broad peak of unknown
origin is observed at 0.8 K in the specific heat and magnetic susceptibility,
suggesting the possibility of antiferromagnetic order. We present neutron
diffraction data from polycrystalline samples which do not show any sign of
magnetic scattering below 0.8 K. In addition, we present inelastic neutron
scattering data from a single crystal sample which is consistent with the 1.2 K
energy scale for Kondo spin fluctuations determined from specific heat
measurements.Comment: 4 pages, 2 figures, submitted to J. Mag. Mag. Mater. for ICM 200
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Response to Comment on "A commensal strain of Staphylococcus epidermidis protects against skin neoplasia" by Nakatsuji et al.
Kozmin et al. contend that observations previously reported regarding the antimicrobial and antitumor activities of 6-N-hydroxy aminopurine (6-HAP) were incorrect. Their conclusions rely on poorly characterized reagents and focus strictly on in vitro techniques without validation in relevant mammalian model systems. We are pleased to be able to illuminate the weaknesses in their technical comment. The totality of current results continues to support our original conclusion that a strain of the common human commensal skin bacterium, Staphylococcus epidermidis, produces 6-HAP that can inhibit tumor growth
Raman scattering studies of spin, charge, and lattice dynamics in Ca_{2-x}Sr_{x}RuO_{4} (0 =< x < 0.2)
We use Raman scattering to study spin, charge, and lattice dynamics in
various phases of Ca_{2-x}Sr_{x}RuO_{4}. With increasing substitution of Ca by
Sr in the range 0 =< x < 0.2, we observe (1) evidence for an increase of the
electron-phonon interaction strength, (2) an increased temperature-dependence
of the two-magnon energy and linewidth in the antiferromagnetic insulating
phase, and (3) evidence for charge gap development, and hysteresis associated
with the structural phase change, both of which are indicative of a first-order
metal-insulator transition (T_{MI}) and a coexistence of metallic and
insulating components for T < T_{MI}
Orbital-selective Mott transitions in two-band Hubbard models
The anisotropic two-orbital Hubbard model is investigated at low temperatures
using high-precision quantum Monte Carlo (QMC) simulations within dynamical
mean-field theory (DMFT). We demonstrate that two distinct orbital-selective
Mott transitions (OSMTs) occur for a bandwidth ratio of 2 even without
spin-flip contributions to the Hund exchange, and we quantify numerical errors
in earlier QMC data which had obscured the second transition. The limit of
small inter-orbital coupling is introduced via a new generalized Hamiltonian
and studied using QMC and Potthoff's self-energy functional method, yielding
insight into the nature of the OSMTs and the non-Fermi-liquid OSM phase and
opening the possibility for a new quantum-critical point.Comment: 2 pages, 4 figures, presented at ICM2006 and accepted for JMM
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