Registration Number
0217U002116,
0115U001469
, R & D reports
Title
The study of continuous and granular magnetic nano-films and 2D structures that are urgent for spintronics tasks.
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Head
Ryabchenko Sergiy Mykhajlovych,
Registration Date
19-01-2017
Organization
Institute of physics NASU
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Excitons in double semiconductor quantum wells (QW) are researched. One of these QWs is made of a magnetically-mixed (semimagnetic) semiconductor, Cd1-xMnxTe, and the other from the ordinary one, of CdTe. Magneto-optical investigations are fulfilled in the conditions of the energy of photo-excitation in the vicinity of the energy barrier both slightly higher and slightly below of it. We used a constant width Cd1-xMnxTe QW (15 nm), while the width of CdTe QW varied from 3.9 to 9.1 nm. Barrier width was 1.9 nm, the content of Mn ions, "x", in the semimagnetic QW was 0.05. It was found that along with intensive photoluminescence (PL) of the direct exciton and the trion, which localized in CdTe QW, are observed and ignite with the field two more PL line for case of the width of the CdTe QW 9 nm when the magnetic field is applied to structures with these parameters. One of these lines is connected with direct excitons that are localized in Cd1-xMnxTe QW and the second one with the indirect excitons in which a conduction electron is localized in CdTe QW, and the heavy hole in Cd1-xMnxTe QW. The PL of the indirect excitons is observed in this case in conditions where they are not the lowest excitonic excitations in the system. The manifestations of mixing of states of direct exciton in Cd1-xMnxTe QW and the indirect ones of above-mentioned type was observed in the region of the intersection of the dependencies of their energies from the magnetic field in the region of the 6.8 nm width CdTe QW. It is proposed a modification of the calculation procedure of the Monte Carlo (MC) with the Metropolis algorithm for the calculations of the magnetization reversal in the ensemble of the nanogranular single-domain nanoparticles with strong anisotropy of the "easy plane" and relatively weak one in-plane, between which there is a ferromagnetic exchange-similar interaction, which leads to the formation of superferromagnetic ordering. This modification gives the possibility to reduce the required number of MC iterations and correctly calculate the coercive force for the case of the magnetization reversal in a plane along the axis of easiest magnetization at temperatures below the blocking temperature, Tb, and under conditions where the temperature of the transition to superferromagnetic state is significantly higher of Tb. The results can be used to create spintronic devices using double QW, and, in addition, for the design of the functional elements on the basis nanogranular films. They can also be used in the educational process to describe phenomena in semiconductor QW, and for the interpretation of the concept of "superferromagnetizm" of the nanostructures.
Product Description
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Бондар Олександр Васильович
Калита Віктор Михайлович
Кулик Микола Миколаєвич
Лозенко Альберт Федорович
Рябченко Сергій Михайлович
Терлецький Олег Валентинович
Чорноморець Надія Федорівна
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2020-04-02
