4,176 research outputs found
Effect of disorder on a Pomeranchuk instability
We study the effect of disorder on the order parameter equation and
transition temperature of a Pomeranchuk-type Fermi-surface instability using
replica mean field theory. We consider the example of a phase transition to a
type Fermi surface distortion, and show that, in the regime
where such a transition is second order, the transition temperature is reduced
by disorder in essentially the same way as that for a d-wave superconductor. We
argue that observing this disorder dependence of metal-to-metal transition
might be a useful indicator of a finite angular momentum Fermi surface
distortion.Comment: 4.1 pages, 3 figs. Version as published in EPL. Added data of
Sr3Ru2O7 to theory curves of Fig.2, and some clarification of derivation of
result
A Single-Photon-compatible Telecom-C-Band Quantum Memory in a Hot Atomic Gas
The efficient storage and on-demand retrieval of quantum optical states that
are compatible with the telecommunications C-band is a requirement for future
terrestrial-based quantum optical networking. Spectrum in the C-band minimises
optical fiber-propagation losses, and broad optical bandwidth facilitates
high-speed networking protocols. Here we report on a telecommunication
wavelength and bandwidth compatible quantum memory. Using the Off-Resonant
Cascaded Absorption protocol in hot Rb vapour, we demonstrate a total
memory efficiency of with a Doppler-limited storage time of
ns. We characterise the memory performance with weak coherent
states, demonstrating signal-to-noise ratios greater than unity for mean photon
number inputs above per pulse
A Synchrotron-Based Study of the Mary Rose Iron Cannonballs
Post‐excavation iron corrosion may be accelerated by the presence of Cl^{-} , leading to conservation methods designed to remove Cl. This study exploits a unique opportunity to assess 35 years of conservation applied to cast‐iron cannon shot excavated from the Mary Rose. A combination of synchrotron X‐ray powder diffraction (SXPD), absorption spectroscopy (XAS), and fluorescence (XRF) mapping have been used to characterise the impact of conservation on the crystalline corrosion products, chlorine distribution, and speciation. The chlorinated phase akaganeite, β‐FeO(OH,Cl), was found on shot washed in corrosion inhibitor Hostacor IT with or without an additional reduction stage. No chlorinated phases were observed on the surface of shot stored in sodium sesquicarbonate (Na_{2}CO_{3}/NaHCO_{3}); however, hibbingite, β‐Fe_{2}(OH)_{3}Cl, was present in metal pores. It is proposed that surface β‐FeO(OH,Cl) formed in the early stages of active conservation owing to oxidation of β‐Fe_{2}(OH)_{3}Cl at near‐neutral pH
Finite-Size Bosonization of 2-Channel Kondo Model: a Bridge between Numerical Renormalization Group and Conformal Field Theory
We generalize Emery and Kivelson's (EK) bosonization-refermionization
treatment of the 2-channel Kondo model to finite system size and on the EK-line
analytically construct its exact eigenstates and finite-size spectrum. The
latter crosses over to conformal field theory's (CFT) universal
non-Fermi-liquid spectrum (and yields the most-relevant operators' dimensions),
and further to a Fermi-liquid spectrum in a finite magnetic field. Our approach
elucidates the relation between bosonization, scaling techniques, the numerical
renormalization group (NRG) and CFT. All CFT's Green's functions are recovered
with remarkable ease from the model's scattering states.Comment: 4 pages, 1 figure, Revte
Emergence of the nematic electronic state in FeSe
We present a comprehensive study of the evolution of the nematic electronic
structure of FeSe using high resolution angle-resolved photoemission
spectroscopy (ARPES), quantum oscillations in the normal state and
elastoresistance measurements. Our high resolution ARPES allows us to track the
Fermi surface deformation from four-fold to two-fold symmetry across the
structural transition at ~87 K which is stabilized as a result of the dramatic
splitting of bands associated with dxz and dyz character. The low temperature
Fermi surface is that a compensated metal consisting of one hole and two
electron bands and is fully determined by combining the knowledge from ARPES
and quantum oscillations. A manifestation of the nematic state is the
significant increase in the nematic susceptibility as approaching the
structural transition that we detect from our elastoresistance measurements on
FeSe. The dramatic changes in electronic structure cannot be explained by the
small lattice effects and, in the absence of magnetic fluctuations above the
structural transition, points clearly towards an electronically driven
transition in FeSe stabilized by orbital-charge ordering.Comment: Latex, 8 pages, 4 figure
Software and information life cycle (SILC) for the Integrated Information Services Organization
This document describes the processes to be used for creating corporate information systems within the scope of the Integrated Information Services (IIS) Center. Issue B describes all phases of the life cycle, with strong emphasis on the interweaving of the Analysis and Design phases. This Issue B supersedes Issue A, which concentrated on the Analysis and Implementation phases within the context of the entire life cycle. Appendix A includes a full set of examples of the deliverables, excerpted from the Network Database. Subsequent issues will further develop these life cycle processes as we move toward enterprise-level management of information assets, including information meta-models and an integrated corporate information model. The phases described here, when combined with a specifications repository, will provide the basis for future reusable components and improve traceability of information system specifications to enterprise business rules
The spectrum of BPS branes on a noncompact Calabi-Yau
We begin the study of the spectrum of BPS branes and its variation on lines
of marginal stability on O_P^2(-3), a Calabi-Yau ALE space asymptotic to
C^3/Z_3. We show how to get the complete spectrum near the large volume limit
and near the orbifold point, and find a striking similarity between the
descriptions of holomorphic bundles and BPS branes in these two limits. We use
these results to develop a general picture of the spectrum. We also suggest a
generalization of some of the ideas to the quintic Calabi-Yau.Comment: harvmac, 45 pp. (v2: added references
Metamagnetism and critical fluctuations in high quality single crystals of the bilayer ruthenate Sr3Ru2O7
We report the results of low temperature transport, specific heat and
magnetisation measurements on high quality single crystals of the bilayer
perovskite Sr3Ru2O7, which is a close relative of the unconventional
superconductor Sr2RuO4. Metamagnetism is observed, and transport and
thermodynamic evidence for associated critical fluctuations is presented. These
relatively unusual fluctuations might be pictured as variations in the Fermi
surface topography itself. No equivalent behaviour has been observed in the
metallic state of Sr2RuO4.Comment: 4 pages, 4 figures, Revtex 3.
Effect of Fermi Surface Topology on Inter-Layer Magnetoresistance in Layered Multiband Systems: Application to LaFeAsO1-xFx
In layered single band systems, the interlayer conductivity depends on the
orientation of the in-plane magnetic field and takes maximum values when the
magnetic field is perpendicular to flat regions of the Fermi surface. Extending
this known results to multi-band systems, we propose an experiment to extract
information about their Fermi surface topology. We discuss application of the
formula to a FeAs-based superconductor, LaFeAsOF. We show that the
magnetically ordered state in the parent compound is clearly distinguished from
the paramagnetic state by the oscillation period in the interlayer
conductivity. We demonstrate that evolution of the Fermi surface topology by
changing the doping concentration is reflected to the interlayer conductivity
oscillation patterns.Comment: 12 pages, 6 figures, corrected Fig.6, added clarifications and refs,
to appear in J. Phys. Soc. Jp
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