20,017 research outputs found
Pressure effects on the heavy-fermion antiferromagnet CeAuSb2
The f-electron compound CeAuSb2, which crystallizes in the ZrCuSi2-type
tetragonal structure, orders antiferromagnetically between 5 and 6.8 K, where
the antiferromagnetic transition temperature T_N depends on the occupancy of
the Au site. Here we report the electrical resistivity and heat capacity of a
high-quality crystal CeAuSb2 with T_N of 6.8 K, the highest for this compound.
The magnetic transition temperature is initially suppressed with pressure, but
is intercepted by a new magnetic state above 2.1 GPa. The new phase shows a
dome shape with pressure and coexists with another phase at pressures higher
than 4.7 GPa. The electrical resistivity shows a T^2 Fermi liquids behavior in
the complex magnetic state, and the residual resistivity and the T^2
resistivity coefficient increases with pressure, suggesting the possibility of
a magnetic quantum critical point at a higher pressure.Comment: 5 pages, 5 firure
Putative spin liquid in the triangle-based iridate BaIrTiO
We report on thermodynamic, magnetization, and muon spin relaxation
measurements of the strong spin-orbit coupled iridate BaIrTiO,
which constitutes a new frustration motif made up a mixture of edge- and
corner-sharing triangles. In spite of strong antiferromagnetic exchange
interaction of the order of 100~K, we find no hint for long-range magnetic
order down to 23 mK. The magnetic specific heat data unveil the -linear and
-squared dependences at low temperatures below 1~K. At the respective
temperatures, the zero-field muon spin relaxation features a persistent spin
dynamics, indicative of unconventional low-energy excitations. A comparison to
the isostructural compound BaRuTiO suggests that a concerted
interplay of compass-like magnetic interactions and frustrated geometry
promotes a dynamically fluctuating state in a triangle-based iridate.Comment: Physical Review B accepte
Hybridization gap and Fano resonance in SmB
We present results of Scanning Tunneling Microscopy and Spectroscopy (STS)
measurements on the "Kondo insulator" SmB. The vast majority of surface
areas investigated was reconstructed but, infrequently, also patches of varying
size of non-reconstructed, Sm- or B-terminated surfaces were found. On the
smallest patches, clear indications for the hybridization gap and
inter-multiplet transitions were observed. On non-reconstructed surface areas
large enough for coherent co-tunneling we were able to observe clear-cut Fano
resonances. Our locally resolved STS indicated considerable finite conductance
on all surfaces independent of their structure.Comment: 5 pages, 4 figure
Accelerated Curing and Enhanced Material Properties of Conductive Polymer Nanocomposites by Joule Heating
Joule heating is useful for fast and reliable manufacturing of conductive composite materials. In this study, we investigated the influence of Joule heating on curing conditions and material properties of polymer-based conductive composite materials consisting of carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS). We applied different voltages to the CNT nanocomposites to investigate their electrical stabilization, curing temperature, and curing time. The result showed that highly conductive CNT/PDMS composites were successfully cured by Joule heating with uniform and fast heat distribution. For a 7.0 wt % CNT/PDMS composite, a high curing temperature of around 100 °C was achieved at 20 V with rapid temperature increase. The conductive nanocomposite cured by Joule heating also revealed an enhancement in mechanical properties without changing the electrical conductivities. Therefore, CNT/PDMS composites cured by Joule heating are useful for expediting the manufacturing process for particulate conductive composites in the field of flexible and large-area sensors and electronics, where fast and uniform curing is critical to their performance
Permutation sampling in Path Integral Monte Carlo
A simple algorithm is described to sample permutations of identical particles
in Path Integral Monte Carlo (PIMC) simulations of continuum many-body systems.
The sampling strategy illustrated here is fairly general, and can be easily
incorporated in any PIMC implementation based on the staging algorithm.
Although it is similar in spirit to an existing prescription, it differs from
it in some key aspects. It allows one to sample permutations efficiently, even
if long paths (e.g., hundreds, or thousands of slices) are needed. We
illustrate its effectiveness by presenting results of a PIMC calculation of
thermodynamic properties of superfluid Helium-four, in which a very simple
approximation for the high-temperature density matrix was utilized
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