We review the photosignal formation mechanisms, architecture, and main parameters of photosensors based on group-III, IV, V, and VI monoatomic 2D materials, specifically, graphene and graphene-like ...materials, silicene, germanene, black phosphorus, black phosphorus‒arsenic solid solutions, antimonene, bismuthene, tellurene, borophene, and heterostructures containing 2D materials, including those combined with other low-dimensional materials, as well as photosensors with plasmonic nanoantennas.
We review the design and main parameters of field-effect transistors based on 2D structures of transition metal di- and trichalcogenides MoS
2
, MoSe
2
, MoTe
2
, WS
2
, WSe
2
, Mo
1 ‒
x
W
x
Se
2
, ...ZrS
2
, ZrSe
2
, HfS
2
, HfSe
2
, PtS
2
, PtSe
2
, PtTe
2
, PdSe
2
, ReS
2
, ReSe
2
, HfS
3
, ZrS
3
, TiS
3
, TaSe
3
, and NbS
3
, as well as monoatomic phosphorene (2DbP), antimonene (2DSb), arsenene (2DAs), silicene (2DSi), germanene (2DGe), and stanene (2DSn). Field-effect nanotransistors on flexible substrates, tunnel, and single-electron transistors based on van der Waals structures of graphene quantum dots, as well as transistors containing 2D heteropairs Gr‒(h)BN, Gr‒WS
2
, Gr‒(h)BC
2
N, Gr‒FGr, SnS
2
‒WS
2
, SnSe
2
‒WSe
2
, HfS
2
‒MoS
2
, PdSe
2
‒MoS
2
, and WSe
2
‒WO
3 –
x
are discussed.
How to make a mature accreting magnetar Igoshev, A. P; Popov, S. B
Monthly notices of the Royal Astronomical Society,
01/2018, Letnik:
473, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Abstract
Several candidates for accreting magnetars have been proposed recently by different authors. Existence of such systems contradicts the standard magnetic field decay scenario where a large ...magnetic field of a neutron star reaches ≲a few ×1013 G at ages ≳1 Myr. Among other sources, the high-mass X-ray binary 4U 0114+65 seems to have a strong magnetic field around 1014 G. We develop a new Bayesian estimate for the kinematic age and demonstrate that 4U 0114+65 has kinematic age 2.4–5 Myr (95 per cent credential interval) since the formation of the neutron star. We discuss which conditions are necessary to explain the potential existence of magnetars in accreting high-mass binaries with ages about few Myr and larger. Three necessary ingredients are: the Hall attractor to prevent rapid decay of dipolar field, relatively rapid cooling of the crust in order to avoid Ohmic decay due to phonons, and finally, low values of the parameter Q to obtain long Ohmic time-scale due to impurities. If age and magnetic field estimates for proposed accreting magnetars are correct, then these systems set the strongest limit on the crust impurity for a selected sample of neutron stars and provide evidence in favour of the Hall attractor.
Photoelectronics Based on 0D Materials Ponomarenko, V. P.; Popov, V. S.; Popov, S. V.
Journal of communications technology & electronics,
12/2022, Letnik:
67, Številka:
Suppl 1
Journal Article
Recenzirano
—
The arrangement and main parameters of the photosensory structures and devices based on quantum dots of the elements of the II, IV, and VI groups of the periodic table made by colloidal chemistry ...methods have been described. The hybrid structural schemes of photoresistive, photodiode, and phototransistor elements with absorbing layers based on the HgTe, HgSe, PbS, and PbSe colloidal quantum dots (CQDs) for operation in various spectral ranges including using 2D materials have been considered.
The structure and main parameters of field-effect transistors (FETs) based on gapless graphene (Gr) and its derivatives with semiconducting properties, transistors on flexible substrates, tunneling ...transistors (TFETs) based on graphene mono- and bilayers, and transistors based on graphene nanoribbons are described.
The design of branched transmissions of multi-axle vehicles, multistage steering systems and automated workflow control systems requires their preliminary dynamic calculation. These calculations are ...based on mathematical models of structural elements corresponding to the modern level of development of system theory, i.e. taking into account dynamic interrelations between the system links. The aim of the work is to build a mathematical model of the automobile wheeled propulsor intended for use in the dynamic model of the "car-road" system or models of separate automobile systems. The approach to mathematical modeling of the automobile wheeled propulsor is offered, consisting in its description by methods of the control theory as an element of dynamic system. The method of construction and analysis of the complete system of equations of kinematic bonds superimposed in the contact zone on the movement of points of the external surface of the tire of linear elastic wheel at its perturbed rectilinear rolling on a solid uneven support surface is developed. The method of construction of a transfer matrix of automobile linear elastic wheel at which its structure practically does not depend on features of the settlement scheme of the tyres is developed too in this study. The method of obtaining the tire characteristics necessary for the calculation of the transfer matrix elements by the generalized method of successive approximations, which gives the qualitatively correct results in zero approximation, is proposed. The method of qualitative theoretical analysis of the features of rectilinear stationary rolling of the automobile wheel is given in this paper. The results allow to carry out researches and calculations of dynamic characteristics of automobile systems, units and assemblies directly interacting with the wheel; they can serve as a basis for further improvement of mathematical models of automobile ruts by methods of system theory.
We present estimates of initial spin periods,
P
0
, for radio pulsars associated with supernova remnants. By using the published data on 30 objects, we were able to derive a reliable estimate for the ...initial spin period, assuming standard magneto-dipole spin-down (braking index
n
=3), in many cases. Our set of estimates is still not sufficient to infer the exact shape of the initial period distribution. However, we show that a gaussian distribution with mean and deviation ∼0.1 s is consistent with our results, while flat, wide distributions and very narrow ones are disfavored.
It has long been unclear if the small-scale magnetic structures on the neutron star (NS) surface could survive the fall-back episode. The study of the Hall cascade by Cumming, Arras & Zweibel hinted ...that energy in small-scales structures should dissipate on short time-scales. Our new 2D magneto-thermal simulations suggest the opposite. For the first ∼10 kyr after the fall-back episode with accreted mass 10−3 M⊙, the observed NS magnetic field appears dipolar, which is insensitive to the initial magnetic topology. In framework of the Ruderman & Sutherland, vacuum gap model during this interval, non-thermal radiation is strongly suppressed. After this time, the initial (i.e. multipolar) structure begins to re-emerge through the NS crust. We distinguish three evolutionary epochs for the re-emergence process: the growth of internal toroidal field, the advection of buried poloidal field, and slow Ohmic diffusion. The efficiency of the first two stages can be enhanced when small-scale magnetic structure is present. The efficient re-emergence of high-order harmonics might significantly affect the curvature of the magnetospheric field lines in the emission zone. So, only after few 104 yr would be the NS starts shining as a pulsar again, which is in correspondence with radio silence of central compact objects. In addition, these results can explain the absence of good candidates for thermally emitting NSs with freshly re-emerged field among radio pulsars (), as NSs have time to cool down, and supernova remnants can already dissipate.
We discuss identification of possible counterparts and persistent sources related to fast radio bursts (FRBs) in the framework of the model of supergiant pulses from young neutron stars with large ...spin-down luminosities. In particular, we demonstrate that at least some of the sources of FRBs can be observed as ultraluminous X-ray sources (ULXs). At the moment no ULXs are known to be coincident with localization areas of FRBs. We searched for a correlation of FRB positions with galaxies in the 2MASS Redshift survey catalogue. Our analysis produced statistically insignificant overabundance (p-value ≈ 4 per cent) of galaxies in error boxes of FRBs. In the very near future with even modestly increased statistics of FRBs and with the help of dedicated X-ray observations and all-sky X-ray surveys it will be possible to decisively prove or falsify the supergiant pulses model.
We use a modified pulsar current analysis to study magnetic field decay in radio pulsars. In our approach, we analyse the flow not along the spin period axis as has been performed in previous ...studies, but study the flow along the direction of growing characteristic age,
$\tau =P/(2\dot{P})$
. We perform extensive tests of the method and find that in most of the cases it is able to uncover non-negligible magnetic field decay (more than a few tens of per cent during the studied range of ages) in normal radio pulsars for realistic initial properties of neutron stars. However, precise determination of the magnetic field decay time-scale is not possible at present. The estimated time-scale may differ by a factor of few for different sets of initial distributions of neutron star parameters. In addition, some combinations of initial distributions and/or selection effects can also mimic enhanced field decay. We apply our method to the observed sample of radio pulsars at distances <10 kpc in the range of characteristic ages 8 × 104 < τ < 106 yr where, according to our study, selection effects are minimized. By analysing pulsars in the Parkes Multibeam and Swinburne surveys, we find that, in this range, the field decays roughly by a factor of 2. With an exponential fit, this corresponds to the decay time-scale ∼4 × 105 yr. With larger statistics and better knowledge of the initial distribution of spin periods and magnetic field strength, this method can be a powerful tool to probe magnetic field decay in neutron stars.
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