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Wyszukujesz frazę "Persson, A." wg kryterium: Autor


Wyświetlanie 1-4 z 4
Tytuł:
XANES Studies of Mn K and $L_{3,2}$ Edges in the (Ga,Mn)As Layers Modified, by High Temperature Annealing
Autorzy:
Wolska, A.
Lawniczak-Jablonska, K.
Klepka, M.
Jakieła, R.
Demchenko, I.
Sadowski, J.
Holub-Krappe, E.
Persson, A.
Arvanitis, D.
Powiązania:
https://bibliotekanauki.pl/articles/1812244.pdf
Data publikacji:
2008-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Dm
75.50.Pp
Opis:
$Ga_{1-x}Mn_xAs$ is commonly considered as a promising material for microelectronic applications utilizing the electron spin. One of the ways that allow increasing the Curie temperature above room temperature is to produce second phase inclusions. In this paper $Ga_{1-x}Mn_xAs$ samples containing precipitations of ferromagnetic MnAs are under consideration. We focus on the atomic and electronic structure around the Mn atoms relating to the cluster formation. The changes in the electronic structure of the Mn, Ga and As atoms in the (Ga,Mn)As layers after high temperature annealing were determined by X-ray absorption near edge spectroscopy. The experimental spectra were compared with the predictions of ab initio full multiple scattering theory using the FEFF 8.4 code. The nominal concentration of the Mn atoms in the investigated samples was 6% and 8%. We do not observe changes in the electronic structure of Ga and As introduced by the presence of the Mn atoms. We find, in contrast, considerable changes in the electronic structure around the Mn atoms. Moreover, for the first time it was possible to indicate the preferred interstitial positions of the Mn atoms.
Źródło:
Acta Physica Polonica A; 2008, 114, 2; 357-366
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Morphology and Magnetic Coupling in ZnO:Co and ZnO:Ni Co-Doped with Li
Autorzy:
Persson, C.
Jayakumar, O.
Sudakar, C.
Sudarsan, V.
Tyagi, A.
Powiązania:
https://bibliotekanauki.pl/articles/1505447.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Nr
71.55.Gs
75.50.-y
Opis:
$Zn_{0.95}Co_{0.05}O$ and $Zn_{0.97}Ni_{0.03}O$ nanorods, prepared by a solvothermal method, show intriguing morphology and magnetic properties when co-doped with Li. At low and moderate Li incorporation (below 10 and 3 at.% Li in the Co- and Ni-doped samples, respectively) the rod aspect ratio is increased and room temperature ferromagnetic properties are enhanced, whereas the ferromagnetic coupling in $Zn_{0.97}Ni_{0.03}O$ is decreased for Li concentrations < 3 at.%. First-principles theoretical analyses demonstrate that Li co-doping has primarily two effects in bulk $Zn_{1- x}M_{x}O$ (with M = Co or Ni). First, the Li-on-Zn acceptors increase the local magnetic moment by depopulating the M 3d minority spin-states. The magnetic coupling is Ruderman-Kittel-Kasuya-Yosida-like both without and with Li co-doping. Second, Li-on-Zn prefer to be close to the M atoms to compensate the M-O bonds and to locally depopulate the 3d states, and this will help forming high aspect nanostructures. The observed room temperature ferromagnetism in Li co-doped $Zn_{1- x}M_{x}O$ nanorods can therefore be explained by the better rod morphology in combination with ionizing the magnetic M atoms.
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 95-98
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Well-Width Fluctuations on the Electronic Structure of GaN/Al$\text{}_{x}$Ga$\text{}_{1-x}$N Multiquantum Wells with Graded Interfaces
Autorzy:
Valcheva, E.
Dimitrov, S.
Monemar, B.
Haratizadeh, H.
Persson, P.O.A.
Amano, H.
Akasaki, I.
Powiązania:
https://bibliotekanauki.pl/articles/2047708.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
73.20.-r
73.21.-b
74.40.+k
Opis:
Experimental and computation results based on chemical composition assessment of metal-organic chemical vapour deposition grown undoped GaN/Al$\text{}_{x}$Ga$\text{}_{1-x}$N multiquantum well structures in the low composition limit of x = 0.07 and wide wells demonstrate composition fluctuations in the barrier layers which lead to large-scale nonuniformities and inequivalence of the different wells. As a consequence the experimental photoluminescence spectra at low temperature show a double peak structure indicative of well-width fluctuations by one lattice parameter (2 monolayers).
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 395-400
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Increasing Precision and Yield in Casting Production by Simulation of the Solidification Process Based on Realistic Material Data Evaluated from Thermal Analysis (Using the ATAS MetStar System)
Autorzy:
Persson, P-E
Ignaszak, Z.
Fransson, H.
Kropotkin, V.
Andersson, R.
Kump, A.
Powiązania:
https://bibliotekanauki.pl/articles/382019.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ductile iron
simulation
defect prognosis
density calibration
thermal analysis
żeliwo sferoidalne
symulacja
prognozowanie defektów
kalibracja gęstości
analiza termiczna
Opis:
The conducted work shows and confirms how thermal analysis of grey and ductile iron is an important source for calculating metallurgical data to be used as input to increase the precision in simulation of cooling and solidification of cast iron. The aim with the methodology is to achieve a higher quality in the prediction of macro– and micro porosity in castings. As comparison objects standard type of sampling cups for thermal analysis (solidification module M ≈ 0.6 cm) is used. The results from thermal analysis elaborated with the ATAS MetStar system are evaluated parallel with the material quality (including tendency to external and internal defects) of the tested specimen. Significant temperatures and calculated quality parameters are evaluated in the ATAS MetStar system and used as input to calibrate the density curve as temperature function in NovaFlow&Solid simulation system. The modified data are imported to the NovaFlow&Solid simulation system and compared with real results.
Źródło:
Archives of Foundry Engineering; 2019, 1; 109-116
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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