140 research outputs found
Non-contact method for measurement of the microwave conductivity of graphene
We report a non-contact method for conductivity and sheet resistance
measurements of graphene samples using a high Q microwave dielectric resonator
perturbation technique, with the aim of fast and accurate measurement of
microwave conductivity and sheet resistance of monolayer and few layers
graphene samples. The dynamic range of the microwave conductivity measurements
makes this technique sensitive to a wide variety of imperfections and
impurities and can provide a rapid non-contacting characterisation method.
Typically the graphene samples are supported on a low-loss dielectric
substrate, such as quartz, sapphire or SiC. This substrate is suspended in the
near-field region of a small high Q sapphire puck microwave resonator. The
presence of the graphene perturbs both centre frequency and Q value of the
microwave resonator. The measured data may be interpreted in terms of the real
and imaginary components of the permittivity, and by calculation, the
conductivity and sheet resistance of the graphene. The method has great
sensitivity and dynamic range. Results are reported for graphene samples grown
by three different methods: reduced graphene oxide (GO), chemical vapour
deposition (CVD) and graphene grown epitaxially on SiC. The latter method
produces much higher conductivity values than the others.Comment: 8 pages, 2 figures and 2 table
Affine spherical homogeneous spaces with good quotient by a maximal unipotent subgroup
For an affine spherical homogeneous space G/H of a connected semisimple
algebraic group G, we consider the factorization morphism by the action on G/H
of a maximal unipotent subgroup of G. We prove that this morphism is
equidimensional if and only if the weight semigroup of G/H satisfies some
simple condition.Comment: v2: title and abstract changed; v3: 16 pages, minor correction
Terahertz radiation driven chiral edge currents in graphene
We observe photocurrents induced in single layer graphene samples by
illumination of the graphene edges with circularly polarized terahertz
radiation at normal incidence. The photocurrent flows along the sample edges
and forms a vortex. Its winding direction reverses by switching the light
helicity from left- to right-handed. We demonstrate that the photocurrent stems
from the sample edges, which reduce the spatial symmetry and result in an
asymmetric scattering of carriers driven by the radiation electric field. The
developed theory is in a good agreement with the experiment. We show that the
edge photocurrents can be applied for determination of the conductivity type
and the momentum scattering time of the charge carriers in the graphene edge
vicinity.Comment: 4 pages, 4 figure, additional Supplemental Material (3 pages, 1
figure
Dream in a mode of biological rhythms of student's youth
The healthy lifestyle of any person includes such important concepts as keeping of a mode of work and rest. For activity of a young organism importance of a dream represents special value. However in student's life as all of us know, it is very difficult to keep a constant sleep patternЗдоровый образ жизни любого человека включает такие немаловажные понятия как соблюдение режима труда и отдыха. Для жизнедеятельности молодого организма важность сна представляет особое значение. Однако, в студенческой жизни, как мы все знаем, очень трудно соблюдать постоянный режим сн
ALBUMIN/THIACALIX[4]ARENE NANOPARTICLES AND THEIR SELF-ASSEMBLY WITH CIPROFLOXACIN
The work was supported by Russian Science Foundation (№18-73-10094), https://rscf.ru/project/18-73-10094/
DECASUBSTITUTED PILLAR[5]ARENE DERIVATIVES CONTAINING L-PHENYALANINE RESIDUES:SELF-ASSEMBLY AND INTERACTION WITH CYCLOSPORINE A
The work was supported by Russian Science Foundation (№ 18-73-10094), https://rscf.ru/project/18-73-10094/
AGGREGATION BEHAVIOR OF DECASUBSTITUTED PILLAR[5]ARENE DERIVATIVES CONTAINING GLYCINE AND L-ALANINE RESIDUES
The work was supported by Russian Science Foundation (№ 18-73-10094), https://rscf.ru/project/18-73-10094/
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