2,730 research outputs found
Finite Correlation Length Scaling in Lorentz-Invariant Gapless iPEPS Wave Functions
It is an open question how well tensor network states in the form of an
infinite projected entangled pair states (iPEPS) tensor network can approximate
gapless quantum states of matter. Here we address this issue for two different
physical scenarios: i) a conformally invariant quantum critical point
in the incarnation of the transverse field Ising model on the square lattice
and ii) spontaneously broken continuous symmetries with gapless Goldstone modes
exemplified by the antiferromagnetic Heisenberg and XY models on the
square lattice. We find that the energetically best wave functions display {\em
finite} correlation lengths and we introduce a powerful finite correlation
length scaling framework for the analysis of such finite- iPEPS states. The
framework is important i) to understand the mild limitations of the finite-
iPEPS manifold in representing Lorentz-invariant, gapless many body quantum
states and ii) to put forward a practical scheme in which the finite
correlation length combined with field theory inspired formulae can be
used to extrapolate the data to infinite correlation length, i.e. to the
thermodynamic limit. The finite correlation length scaling framework opens the
way for further exploration of quantum matter with an (expected)
Lorentz-invariant, massless low-energy description, with many applications
ranging from condensed matter to high-energy physics.Comment: 16 pages, 11 figure
Reinforcement of polymeric structures with asbestos fibrils
Investigation determines structural potential of asbestos fibrils. Methods are developed for dispersing macrofibers of the asbestos into colloidal-sized ultimate fibrils and incorporating these fibrils in matrices without causing reagglomeration
A Modern Craftsman Revival
Introducing concepts of Craftsman kit construction to the interior, as well as modern technology to lessen the cost of handcrafted details, opens the possibility to new methods of modular design in which interior units are configured around structural skeletons and central base points that provide supply lines to residential units. One example is Dutch design firm Minale-Maeda’s Keystones, a 3D printed connector that holds together any necessary components, like furniture. These keystones can be printed at home and save time and the need to obtain anything but essential components (website). The design firm works to create an “ongoing awareness of the possibilities of both mass-production and skilled craftsmanship” (L’arco Baleno, 2014). Another interesting example is Dutch design brand Fraaiheid’s Minimal Waste Table, which is created from one piece of laminated plywood with a CNC milling machine which makes for extremely minimal waste (Williamson, 2013). These examples of automation require a craftsman’s hand and mind to create the concept but introduce a modern approach to reducing waste, time and cost
Suppression of electron scattering resonances in graphene by quantum dots
Transmission of low-energetic electrons through two-dimensional materials
leads to unique scattering resonances. These resonances contribute to
photoemission from occupied bands where they appear as strongly dispersive
features of suppressed photoelectron intensity. Using angle-resolved
photoemission we have systematically studied scattering resonances in epitaxial
graphene grown on the chemically differing substrates Ir(111), Bi/Ir, Ni(111)
as well as in graphene/Ir(111) nanopatterned with a superlattice of uniform Ir
quantum dots. While the strength of the chemical interaction with the substrate
has almost no effect on the dispersion of the scattering resonances, their
energy can be controlled by the magnitude of charge transfer from/to graphene.
At the same time, a superlattice of small quantum dots deposited on graphene
eliminates the resonances completely. We ascribe this effect to a
nanodot-induced buckling of graphene and its local rehybridization from
sp to sp towards a three-dimensional structure. Our results suggest
nanopatterning as a prospective tool for tuning optoelectronic properties of
two-dimensional materials with graphene-like structure.Comment: The following article has been submitted to Applied Physics Letters.
If it is published, it will be found online at http://apl.aip.or
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