6,286 research outputs found
The suppression of superconductivity in Mn substituted MgCNi
We report the effect of doping Mn in the isostructural MgCNiMn
(x = 0-0.05) compounds. Magnetic susceptibility, resistivity,
magneto-resistance, and specific heat studies show evidence of localized
moments and Kondo effect in samples with x0. The rapid suppression of
superconductivity ( -21K/at.% Mn) in these compounds is a consequence of
pair breaking effects due to moment formation on Mn.Comment: 9 figures, Accepted for publication in Physical Review B, Added
reference
Adaptive Resolution Molecular Dynamics Simulation: Changing the Degrees of Freedom on the Fly
We present a new adaptive resolution technique for efficient particle-based
multiscale molecular dynamics (MD) simulations. The presented approach is
tailor-made for molecular systems where atomistic resolution is required only
in spatially localized domains whereas a lower mesoscopic level of detail is
sufficient for the rest of the system. Our method allows an on-the-fly
interchange between a given molecule's atomic and coarse-grained level of
description, enabling us to reach large length and time scales while spatially
retaining atomistic details of the system. The new approach is tested on a
model system of a liquid of tetrahedral molecules. The simulation box is
divided into two regions: one containing only atomistically resolved
tetrahedral molecules, the other containing only one particle coarse-grained
spherical molecules. The molecules can freely move between the two regions
while changing their level of resolution accordingly. The coarse-grained and
the atomistically resolved systems have the same statistical properties at the
same physical conditions.Comment: 17 pages, 11 figures, 5 table
Specific Heat of the Ca-Intercalated Graphite Superconductor CaC
The superconducting state of Ca-intercalated graphite CaC6 has been
investigated by specific heat measurements. The characteristic anomaly at the
superconducting transition (Tc = 11.4 K) indicates clearly the bulk nature of
the superconductivity. The temperature and magnetic field dependence of the
electronic specific heat are consistent with a fully-gapped superconducting
order parameter. The estimated electron-phonon coupling constant is lambda =
0.60 - 0.74 suggesting that the relatively high Tc of CaC6 can be explained
within the weak-coupling BCS approach.Comment: 4 pages, 4 figs, submitted to Phys. Rev. Let
Lattice and polarizability mediated spin activity in EuTiO_3
EuTiO_3 is shown to exhibit novel strong spin-charge-lattice coupling deep in
the paramagnetic phase. Its existence is evidenced by an, until now, unknown
response of the paramagnetic susceptibility at temperatures exceeding the
structural phase transition temperature T_S = 282K. The "extra" features in the
susceptibility follow the rotational soft zone boundary mode temperature
dependence above and below T_S. The theoretical modeling consistently
reproduces this behavior and provides reasoning for the stabilization of the
soft optic mode other than quantum fluctuations.Comment: 8 pages, 4 figure
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