5,749 research outputs found
Quantum information approach to the quantum phase transition in the Kitaev honeycomb model
Kitaev honeycomb model with topological phase transition at zero temperature
is studied using quantum information method. Based on the exact solution of the
ground state, the mutual information between two nearest sites and between two
bonds with longest distance are obtained. It is found that the mutual
information show some singularities at the critical point where the ground
state of the system transits from gapless phase to gapped phase. The
finite-size effects and scalar behavior are also studied. The mutual
information can serve as good indicators of the topological phase transition,
since the mutual information catches some global correlation properties of the
system. Meanwhile, this method has other advantages such that the phase
transition can be determined easily and the order parameters are not required
previously, for the order parameters of some topological phase transitions are
hard to know.Comment: 8 pages, 7 figures, published versio
Manipulation of heat current by the interface between graphene and white graphene
We investigate the heat current flowing across the interface between graphene
and hexagonal boron nitride (so-called white graphene) using both molecular
dynamics simulation and nonequilibrium Green's function approaches. These two
distinct methods discover the same phenomena that the heat current is reduced
linearly with increasing interface length, and the zigzag interface causes
stronger reduction of heat current than the armchair interface. These phenomena
are interpreted by both the lattice dynamics analysis and the transmission
function explanation, which both reveal that the localized phonon modes at
interfaces are responsible for the heat management. The room temperature
interface thermal resistance is about mK/W in zigzag
interface and mK/W in armchair interface, which
directly results in stronger heat reduction in zigzag interface. Our
theoretical results provide a specific route for experimentalists to control
the heat transport in the graphene and hexagonal boron nitride compound through
shaping the interface between these two materials.Comment: accepted by EP
The Friedmann equation in modified entropy-area relation from entropy force
According to the formal holographic principle, a modification to the
assumption of holographic principle in Verlinder's investigation of entropy
force is obtained. A more precise relation between entropy and area in the
holographic system is proposed. With the entropy corrections to the
area-relation, we derivate Newton's laws and Einstein equation with a static
spherically symmetric holographic screen. Furthermore we derived the correction
terms to the modified Friedmann equation of the FRW universe starting from the
holographic principle and the Debye model.Comment: Mod. Phys. Lett. A26, 489-500 (2011
Magnetic properties of a novel Pr Fe Ti phase
In a systematic study of the (Pr1−xTix)Fe5 alloy series, the (Pr0.65Ti0.35)Fe5 alloy has been
found to have a dominant phase with either the rhombohedral Th2Zn17 structure or the
newly discovered Nd2(Fe,Ti)19 (S. J. Collocott, R. K. Day, J. B. Dunlop, and R. L. Davis,
in Proceedings of the Seventh International Symposium on Magnetic Anisotropy and
Coercivity in R‐T Alloys, Canberra, July 1992, p. 437) structure, depending on the
annealing procedure. Powder‐x‐ray‐diffraction patterns and scanning electron
microscopy show that the sample annealed at a temperature of 850 °C followed by
1000 °C has the 2:17 structure whereas annealing at 1000 °C directly leads to the new
2:19 structure. Energy‐dispersive x‐ray analysis yields Pr:Fe:Ti ratios of 10.7:86.2:3.1
for the Pr2(Fe,Ti)17 phase and 9.2:85.9:4.9 for the Pr2(Fe,Ti)19 phase.
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Fe Mössbauer
spectroscopy (at 295 K) gives values for the average
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Fe hyperfine field of 15.7 T for the
2:17 phase and 17.5 T for the 2:19 phase, respectively
Enzymes and genes involved in the betalain biosynthesis in higher plants
Betalains, a class of water-soluble nitrogen-containing pigments, replace anthocyanins and serve the analogous functions in 13 families of the order, caryophyllales. They modulate the attractive appearance of plants and protect them against destructive oxidative damage. Their antioxidant roles, radicalscavenging properties in human health and their potential uses in food and pharmaceutical industries have made significant progress achieved in the detection, purification, quantification, structure elucidation of betalains, and in particular in the understanding of biosynthetic pathways of the pigments,the enzymes and their genes involved in the pathways. In this paper, major progress in betalain biosynthesis and the enzymes and genes involved in the biosynthetic pathways in higher plant are reviewed, and the perspectives discussed
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