4,669 research outputs found
Pseudodoping of Metallic Two-Dimensional Materials by The Supporting Substrates
We demonstrate how hybridization between a two-dimensional material and its
substrate can lead to an apparent heavy doping, using the example of monolayer
TaS grown on Au(111). Combining calculations, scanning
tunneling spectroscopy experiments and a generic model, we show that strong
changes in Fermi areas can arise with much smaller actual charge transfer. This
mechanism, which we refer to as pseudodoping, is a generic effect for metallic
two-dimensional materials which are either adsorbed to metallic substrates or
embedded in vertical heterostructures. It explains the apparent heavy doping of
TaS on Au(111) observed in photoemission spectroscopy and spectroscopic
signatures in scanning tunneling spectroscopy. Pseudodoping is associated with
non-linear energy-dependent shifts of electronic spectra, which our scanning
tunneling spectroscopy experiments reveal for clean and defective TaS
monolayer on Au(111). The influence of pseudodoping on the formation of charge
ordered, magnetic, or superconducting states is analyzed.Comment: arXiv admin note: substantial text overlap with arXiv:1609.0022
On Generators and Relations of the Rational Cohomology of Hilbert Schemes
We consider for the graded commutative -algebra
, which is
also connected to the study of generalised Hurwitz spaces by work of the first
author. These Hurwitz spaces are in turn related to the moduli spaces of
Riemann surfaces with boundary. We determine two distinct, minimal sets of
multiplicative generators of .
Additionally, we prove when the lowest degree generating relations occur. For
small values of we also determine a minimal set of generating relations,
which leads to several conjectures about the necessary generating relations for
.Comment: 25 pages; v2. Minor revisions based on referee's comments. Published
versio
The Spectrum of Yang Mills on a Sphere
In this note, we determine the representation content of the free, large N,
SU(N) Yang Mills theory on a sphere by decomposing its thermal partition
function into characters of the irreducible representations of the conformal
group SO(4,2). We also discuss the generalization of this procedure to finding
the representation content of N=4 Super Yang Mills.Comment: 18 pages v2. references added. typos fixe
Construcción y validación de dos escalas de adherencia a tratamientos de salud
47 p.El objetivo de la presente investigación consiste en construir y validar dos escalas de adherencia a tratamientos de salud en una muestra de 172 mujeres que ingresaban al sistema público de salud chileno para ser tratadas por depresión. Para ello se seleccionó 12 escalas fiables de adherencia desde las cuales se extrajeron y adaptaron los ítems, además de diseñar otros nuevos. Después de seleccionar los ítems más adecuados, se determinó su validez de
constructo mediante un análisis factorial exploratorio (EFA). Los resultados de los EFA arrojan la existencia de 4 factores para la adherencia al tratamiento general y 1 para el tratamiento farmacológico. Luego, para confirmar esta estructura exploratoria, se realizó un análisis factorial confirmatorio (CFA). Como resultado, se obtiene un modelo de buen ajuste para la adherencia al tratamiento general (CMIN/DF=2.879; RMSEA=.108; NFI=.780;
CFI=.843; TLI=.819; PNFI=.680; SMC=.590) y regular para el tratamiento farmacológico
(CMIN/DF=3.084 RMSEA=.116; NFI=.925; CFI=.947; TLI=.932; PNFI=.719; SMC=.652).
Además, se determina la confiabilidad de las escalas, donde ambas presentan indicadores
excelentes (F=.901 y F=.949, respectivamente). Los resultados de esta investigación logran profundizar hallazgos anteriores (Nguyen et al. 2014) y enriquecer el concepto de adherencia, recabando información más precisa acerca de los distintos comportamientos, barreras y
creencias asociadas a la adherencia. Finalmente, con el fin de facilitar la evaluación de la adherencia, se deja a disposición de los clínicos una versión de cada escala para ser aplicada e
interpretada rápidamente.Palabras Clave: Adherencia al tratamiento, adherencia a medicación, validación de escala, análisis factorial
Band gap engineering by Bi intercalation of graphene on Ir(111)
We report on the structural and electronic properties of a single bismuth
layer intercalated underneath a graphene layer grown on an Ir(111) single
crystal. Scanning tunneling microscopy (STM) reveals a hexagonal surface
structure and a dislocation network upon Bi intercalation, which we attribute
to a Bi structure on the underlying Ir(111)
surface. Ab-initio calculations show that this Bi structure is the most
energetically favorable, and also illustrate that STM measurements are most
sensitive to C atoms in close proximity to intercalated Bi atoms. Additionally,
Bi intercalation induces a band gap (eV) at the Dirac point of
graphene and an overall n-doping (eV), as seen in angular-resolved
photoemission spectroscopy. We attribute the emergence of the band gap to the
dislocation network which forms favorably along certain parts of the moir\'e
structure induced by the graphene/Ir(111) interface.Comment: 5 figure
Crystalline and electronic structure of single-layer TaS
Single-layer TaS is epitaxially grown on Au(111) substrates. The
resulting two-dimensional crystals adopt the 1H polymorph. The electronic
structure is determined by angle-resolved photoemission spectroscopy and found
to be in excellent agreement with density functional theory calculations. The
single layer TaS is found to be strongly n-doped, with a carrier
concentration of 0.3(1) extra electrons per unit cell. No superconducting or
charge density wave state is observed by scanning tunneling microscopy at
temperatures down to 4.7 K.Comment: 6 pages, 4 figure
Chirality of tensor perturbations for complex values of the Immirzi parameter
In this paper we generalise previous work on tensor perturbations in a de
Sitter background in terms of Ashtekar variables to cover all complex values of
the Immirzi parameter gamma (previous work was restricted to imaginary gamma).
Particular attention is paid to the case of real gamma. Following the same
approach as in the imaginary case, we can obtain physical graviton states by
invoking reality and torsion free conditions. The Hamiltonian in terms of
graviton states has the same form whether gamma has a real part or not; however
changes occur for the vacuum energy and fluctuations. Specifically, we observe
a gamma dependent chiral asymmetry in the vacuum fluctuations only if gamma has
an imaginary part. Ordering prescriptions also change this asymmetry. We thus
present a measurable result for CMB polarisation experiments that could shed
light on the workings of quantum gravity.Comment: 6 pages, 1 figur
Malignant melanoma associated with a blue naevus: a case report
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
Absence of superconductivity in ultra-thin layers of FeSe synthesized on a topological insulator
The structural and electronic properties of FeSe ultra-thin layers on
BiSe have been investigated with a combination of scanning
tunneling microscopy and spectroscopy and angle-resolved photoemission
spectroscopy. The FeSe multi-layers, which are predominantly 3-5 monolayers
(ML) thick, exhibit a hole pocket-like electron band at \bar{\Gamma} and a
dumbbell-like feature at \bar{M}, similar to multi-layers of FeSe on
SrTiO. Moreover, the topological state of the Bi2Se3 is preserved beneath
the FeSe layer, as indicated by a heavily \it{n}-doped Dirac cone. Low
temperature STS does not exhibit a superconducting gap for any investigated
thickness down to a temperature of 5 K
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