1,768 research outputs found
‘It will be hard because I will have to learn lots of English’: Experiences of education for children newly arrived in Australia
“This is an Accepted Manuscript of an article published by Taylor & Francis in [International Journal of Qualitative Studies in Education,] on [01 Jan 2015], available online: http://
www.tandfonline.com/10.1080/09518398.2015.1023232.”Educational experiences during childhood are critically important for development, but migrant children often experience unique challenges. To ameliorate these, extra training in English language - such as provided by the Intensive English language program in South Australia (IELP) - is frequently offered to children taking on English as an additional language (EAL). The present study aimed to examine the experience of transition into mainstream classes for children in the IELP, particularly in relation to their overall wellbeing. As such, the study utilised interviews conducted with newly arrived children in Australia aged five to 13 who were enrolled in an IELP, with interviews conducted both pre and post transition into mainstream primary school classes. The findings indicate that most children felt anxious prior to transition, especially regarding speaking English, but were less concerned about this once entering their new class. Making friends was considered to be difficult, but easier when there were children with whom they were familiar from other contexts, or if there was another child in the class with a shared cultural or linguistic background
Evidence for Interlayer Electronic Coupling in Multilayer Epitaxial Graphene from Polarization Dependent Coherently Controlled Photocurrent Generation
Most experimental studies to date of multilayer epitaxial graphene on C-face
SiC have indicated that the electronic states of different layers are decoupled
as a consequence of rotational stacking. We have measured the third order
nonlinear tensor in epitaxial graphene as a novel approach to probe interlayer
electronic coupling, by studying THz emission from coherently controlled
photocurrents as a function of the optical pump and THz beam polarizations. We
find that the polarization dependence of the coherently controlled THz emission
expected from perfectly uncoupled layers, i.e. a single graphene sheet, is not
observed. We hypothesize that the observed angular dependence arises from weak
coupling between the layers; a model calculation of the angular dependence
treating the multilayer structure as a stack of independent bilayers with
variable interlayer coupling qualitatively reproduces the polarization
dependence, providing evidence for coupling.Comment: submitted to Nano Letter
Microscopic correlation between chemical and electronic states in epitaxial graphene on SiC(000-1)
We present energy filtered electron emission spectromicroscopy with spatial
and wave-vector resolution on few layer epitaxial graphene on SiC$(000-1) grown
by furnace annealing. Low energy electron microscopy shows that more than 80%
of the sample is covered by 2-3 graphene layers. C1s spectromicroscopy provides
an independent measurement of the graphene thickness distribution map. The work
function, measured by photoelectron emission microscopy (PEEM), varies across
the surface from 4.34 to 4.50eV according to both the graphene thickness and
the graphene-SiC interface chemical state. At least two SiC surface chemical
states (i.e., two different SiC surface structures) are present at the
graphene/SiC interface. Charge transfer occurs at each graphene/SiC interface.
K-space PEEM gives 3D maps of the k_|| pi - pi* band dispersion in micron scale
regions show that the Dirac point shifts as a function of graphene thickness.
Novel Bragg diffraction of the Dirac cones via the superlattice formed by the
commensurately rotated graphene sheets is observed. The experiments underline
the importance of lateral and spectroscopic resolution on the scale of future
electronic devices in order to precisely characterize the transport properties
and band alignments
Highly-ordered graphene for two dimensional electronics
With expanding interest in graphene-based electronics, it is crucial that
high quality graphene films be grown. Sublimation of Si from the 4H-SiC(0001)
Si-terminated) surface in ultrahigh vacuum is a demonstrated method to produce
epitaxial graphene sheets on a semiconductor. In this paper we show that
graphene grown from the SiC (C-terminated) surface are of higher
quality than those previously grown on SiC(0001). Graphene grown on the C-face
can have structural domain sizes more than three times larger than those grown
on the Si-face while at the same time reducing SiC substrate disorder from
sublimation by an order of magnitude.Comment: Submitted to Appl. Phys. Let
Theoretical Aspects of the Fractional Quantum Hall Effect in Graphene
We review the theoretical basis and understanding of electronic interactions
in graphene Landau levels, in the limit of strong correlations. This limit
occurs when inter-Landau-level excitations may be omitted because they belong
to a high-energy sector, whereas the low-energy excitations only involve the
same level, such that the kinetic energy (of the Landau level) is an
unimportant constant. Two prominent effects emerge in this limit of strong
electronic correlations: generalised quantum Hall ferromagnetic states that
profit from the approximate four-fold spin-valley degeneracy of graphene's
Landau levels and the fractional quantum Hall effect. Here, we discuss these
effects in the framework of an SU(4)-symmetric theory, in comparison with
available experimental observations.Comment: 12 pages, 3 figures; review for the proceedings of the Nobel
Symposium on Graphene and Quantum Matte
High-Energy Limit of Massless Dirac Fermions in Multilayer Graphene using Magneto-Optical Transmission Spectroscopy
We have investigated the absorption spectrum of multilayer graphene in high
magnetic fields. The low energy part of the spectrum of electrons in graphene
is well described by the relativistic Dirac equation with a linear dispersion
relation. However, at higher energies (>500 meV) a deviation from the ideal
behavior of Dirac particles is observed. At an energy of 1.25 eV, the deviation
from linearity is 40 meV. This result is in good agreement with the theoretical
model, which includes trigonal warping of the Fermi surface and higher-order
band corrections. Polarization-resolved measurements show no observable
electron-hole asymmetry.Comment: 4 pages,3 figure
Spectroscopic Measurement of Interlayer Screening in Multilayer Epitaxial Graphene
International audienceThe substrate-induced charge-density profile in carbon face epitaxial graphene is determined using nondegenerate ultrafast midinfrared pump-probe spectroscopy. Distinct zero crossings in the differential transmission spectra are used to identify the Fermi levels of layers within the multilayer stack. Probing within the transmission window of the SiC substrate, we find the Fermi levels of the first four heavily doped layers to be, respectively, 360, 215, 140, and 93 meV above the Dirac point. The charge screening length is determined to be one graphene layer, in good agreement with theoretical predictions
Magnetothermoelectric transport in modulated and unmodulated graphene
We draw motivation from recent experimental studies and present a
comprehensive study of magnetothermoelectric transport in a graphene monolayer
within the linear response regime. We employ the modified Kubo formalism
developed for thermal transport in a magnetic field. Thermopower as well as
thermal conductivity as a function of the gate voltage of a graphene monolayer
in the presence of a magnetic field perpendicular to the graphene plane is
determined for low magnetic fields (~1 Tesla) as well as high fields (~8
Tesla). We include the effects of screened charged impurities on thermal
transport. We find good, qualitative as well as quantitative, agreement with
recent experimental work on the subject. In addition, in order to analyze the
effects of modulation, which can be induced by various means, on the thermal
transport in graphene, we evaluate the thermal transport coefficients for a
graphene monolayer subjected to a periodic electric modulation in a magnetic
field. The results are presented as a function of the magnetic field and the
gate voltage.Comment: 14 pages, 8 figure
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