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1
Content available remote On negative differential mobility in nanophotonic device functionality
Anagnostakis E. A.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2013
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Vol. 17, No 3-4
131--137
EN
The negative differential mobility (NDM) of two-dimensional carrier-gas against some proper external regulator allowing gradual controlled modification of the nanointerfacial environment tends to occur as interwoven with the nanophotonic device functionality. In this work, several instances from our two-decade principal research of both experimental observation and conceptual prediction concerning nanophotonics NDM are reconsidered towards outlining a global potential for the appearance of the effect.
2
Content available remote On a nanophotonic response descriptor
Anagnostakis E. A.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2013
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Vol.17, No 1-2
91--94
EN
The photonic response exhibited by typical semiconductor nanodevices is modeled through a notionally universal descriptor by virtue of the Green’s function associated with the generic complete, inhomogeneous differential equation. It is derived that the photoresponse evolution is expressible as the sum of saturation-limiting linear nanophotonic behavior and a linear superposition of eigenfunctions of the respective homogeneous Fredholm integral equation.
3
Content available remote InP:Fe Nanodiode conductivity current persistent photoenhamcement decey
Zardas G. E., Anagnostakis E. A.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2013
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Vol. 17, No 3-4
139--143
EN
The temporal decay of the persistent photoenhancement of the conductivity current flowing through the active channel of two samples of a typical nanodevice comprising a low resistivity n-type InP:Fe epitaxial layer and a semi-insulating InP:Fe substrate is experimentally investigated at room temperature and interpreted via consideration of the functionality of the diodic interface potential barrier. A mean decay mechanism and its distinct regimes are singled out.
4
Content available remote Effect of annealing on EPR spectra of Ti-Si-C-N samples
Guskos N., Anagnostakis E. A., Zolnierkiewicz G., Typek J., Biedunkiewicz A., Guskos A., Berczynski P.
Materials Science Poland
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2012
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Vol. 30, No. 1
23--31
EN
Two nanocrystalline samples of TiC+SiC+20%C (sample 1) and Si3N4+Si(C,N)+Ti(C,N)+1%C (sample 2) were prepared by non-hydrolytic sol-gel method. The latter sample was produced from sample 1, by subjecting it to additional annealing at high temperature. XRD measurements showed the presence of aggregates of cubic SiC+TiC nanoparticles (10 to 30 nm in size). In both samples, a very narrow electron paramagnetic resonance (EPR) line originating from localized magnetic centers was centered at geff2. At T = 130 K, we registered the linewidths DHpp = 1.41(2) G and DHpp = 2.92(2) G for the sample without and with thermal annealing, respectively. For the non-annealed sample, the resonance line was fitted by a Lorentzian line in the low temperature range, and by a Dysonian line above 70 K, which indicates a significant change in electrical conductivity. Therefore, thermal annealing can significantly improve the transport properties of samples. An analysis of the temperature dependence of the EPR parameters (g-factor, linewidth, integrated intensity) showed that thermal annealing has a significant impact on the reorientation processes of localized magnetic centers.
5
Study of magnetic agglomerates in the nanomaterial system (Ti-Si-C(N))/C by the magnetic resonanse technique
Guskos N., Anagnostakis E. A., Żołnierkiewicz G., Typek J., Likodimos V., Guskos A., Biedunkiewicz A.
Elektronika : konstrukcje, technologie, zastosowania
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2008
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Vol. 49, nr 5
18-21
EN
The nanomaterial system (Ti-Si-C(N)) has been prepared by a sol-gel method in flowing nitrogen atmosphere. In its magnetic response a very wide ESR line has been observed, arising from localized magnetic centers, along with an additional very broad and intense line in low magnetic field. The pertinent EPR/FMR parameters (resonance field, linewidth, integrated intensity) have been calculated and studied versus temperature. Analysis of the obtained temperature evolution of the EPR/FMR parameters has revealed characteristics of magnetic interactions between agglomerates and magnetic-dipole localized systems. Magnetic ordering processes for the localized magnetic centers are considered and discussed connected with traceable magnetic agglomerates being liable to enhance magnetic dipole-dipole interactions.
PL
Nanomateriał (Ti-Si-C(N)) został wytworzony metodą sol-żel w strumieniu gazowego azotu. Widmo ERP tego materiału składa się z bardzo wąskiej linii pochodzącej od zlokalizowanych centrów magnetycznych oraz z dodatkowego silnego i szerokiego sygnału znajdującego się w słabym polu magnetycznym. Obliczono standardowe parametry widma ERP/FMR (pole rezonansowe, szerokość linii, intensywność zintegrowana) oraz zbadano ich zależności temperaturowe. Analiza zmian temperaturowych tych parametrów pozwoliła określić charakterystyki oddziaływań magnetycznych pomiędzy aglomeratami i układem zlokalizowanych dipoli magnetycznych. Rozważono możliwość istnienia procesów uporządkowani magnetycznego w układzie zlokalizowanych centrów magnetycznych, które zostały wzmocnione przez system aglomeratów magnetycznych.
6
Content available remote FMR study of magnetic nanoparticles embedded in non-magnetic matrix
Guskos N., Anagnostakis E. A., Guskos A.
Journal of Achievements in Materials and Manufacturing Engineering
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2007
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Vol. 24, nr 1
26-35
EN
Purpose: The aim of this review is recapitulating the FMR study of low concentration of magnetic nanoparticles in non-magnetic matrices. Design/methodology/approach: Magnetic nanoparticles exhibit a variety of anomalous magnetic properties and they could be used for forming low concentration in different matrices. This way, they are being found to be allowing for effectively novel applications of FMR (ferromagnetic resonance) for easier trustworthy characterisation of a variety of materials. alpha-Fe, Co, Fe3C, gamma- Fe203, Fe3O4 magnetic nanoparticles have been used as low concentration fillers in paraffin, concrete, resin and polymers/copolymers. Findings: For all these matrices, the intensities of the FMR spectra are recorded decreasing with temperature lowering in the high temperature region, whilst the resonance locus is shifted to the direction of lower magnetic field, essentially changing the resonance condition. These parameters of the FMR spectra are seen depending upon kind of a nanoparticle host in such a way that this method could be useful for studying dynamical processes of the matrices. Interestingly enough, a very low concentration of magnetic nanoparticles embedded in the non-magnetic matrix could modify its glass-state emanation or melting transition. Research limitations/implications: Composite systems containing magnetic nanoparticles promise the potential for high-density data storage, biomedical applications, catalysis, and nanotechnology sensor materialisation among other envisaged utilisations. Originality/value: Continue attempting to decipher the mystery and fruitfulness of magnetic nanoparticle distributions.
7
Content available remote Finite difference method determination of the nano-hetero-interface wave-function engineering of inter-subband LASER functionality
Anagnostakis E. A.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2004
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Vol. 8, No 3
385-392
EN
A novel LASER action nano-hetero-structure of the inter-subband, mid-infrared functionality type is designed on the basis of optically pumped dual resonant tunnelling of conductivity electrons within an appropriately energetically determined scheme of five subbands hosted by two communicating asymmetric, approximately rectangular quantum wells (QWs). The upper LASER action level employed is the second excited subband of the nanostructure's back, wider QW and is provided with electrons via resonant tunnelling from the first excited subband of the nanostructure's front QW populated through remotely ignited optical pumping out of the local fundamental subband. The first excited back QW subband functions as the lower LASER action level, directly delivering the received electrons to the local fundamental subband - via fast vertical longitudinal optical phonon scattering - wherefrom they are being recycled back to the nanostructure's front QW fundamental subband by virtue of a second-reverse sense-resonant tunnelling-mediated normal charge transport mechanism. The handling of the de Broglie wave-function problem evolves into a numerical calculation of a Sturm-Liouville eigensystem solved by means of a finite difference method employing an appropriate tridiagonal coefficient matrix.
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