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21 results on '"Przybytek, Jacek"'

1. Determining Curie temperature of (Ga,Mn)As samples based on electrical transport measurements: low Curie temperature case

Author

Kwiatkowski, Adam, Gryglas-Borysiewicz, Marta, Juszynski, Piotr, Przybytek, Jacek, Sawicki, Maciej, Sadowski, Janusz, Wasik, Dariusz, and Baj, Michal

Subjects
Condensed Matter - Materials Science
Abstract

In this paper we show that the widely accepted method of the determination of Curie temperature (TC) in (Ga,Mn)As samples, based on the position of the peak in the temperature derivative of the resistivity,completely fails in the case of non-metallic and low-TC unannealed samples. In this case we propose an alternative method, also based on electric transport measurements, which exploits temperature dependence of the second derivative of the resistivity upon magnetic field., Comment: 5 pages, 3 figures

Published
2016
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4. Puzzle of non-surface related 2D electron gas in n-InN epitaxial samples.

Author

Baj, Michał, Dmowski, Lesław H., Kwiatkowski, Adam, Przybytek, Jacek, Wang, Xinqiang, Koblmüller, Gregor, Gallinat, Chad S., and Speck, James S.

Subjects
TWO-dimensional electron gas, ELECTRON gas, ELECTRON mobility, MAGNETIC traps, HALL effect, MAGNETIC fields, TENSOR fields
Abstract

We have studied multicarrier contributions to the conductivity in low concentration (with Hall concentration below 1 × 10 18 cm − 3 ) nondoped bulk n-InN samples using Shubnikov-de Haas (SdH) in the tilted magnetic field as well as variable field resistivity tensor measurements. In some samples, the Shubnikov-de Haas effect also revealed, besides 3D electron gas, high mobility 2D electron contributions (with transport and quantum mobilities reaching the values of 5060 cm 2 /V s and 1800 cm 2 /V s, respectively, for one of our samples), which could hardly be assigned to the surface electrons as the latter are commonly believed to have mobility too low to be detected at magnetic fields not exceeding 12 T in our SdH measurements. The values of the effective masses derived from the temperature dependences of the SdH oscillation amplitudes scale with the concentration of 2D channels and are typical for low concentration InN, thus confirming that these contributions are presumably located on the InN side of some interfaces. This is one of the first experimental evaluations of the effective mass of nonsurface-related 2D electron gas in InN grown on GaN. [ABSTRACT FROM AUTHOR]

Published
2019
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5. Hydrostatic pressure influence on T-C in (Ga,Mn)As

Author

Gryglas-Borysiewicz, Marta, Kwiatkowski, Adam, Juszynski, Piotr, Ogorzalek, Zuzanna, Puzniak, Konrad, Tokarczyk, Mateusz, Kowalski, Grzegorz, Baj, Michal, Wasik, Dariusz, Szwacki, Nevill Gonzalez, Przybytek, Jacek, Sadowski, Janusz, Sawicki, Maciej, Dziawa, Piotr, Domagala, Jaroslaw Z., Gryglas-Borysiewicz, Marta, Kwiatkowski, Adam, Juszynski, Piotr, Ogorzalek, Zuzanna, Puzniak, Konrad, Tokarczyk, Mateusz, Kowalski, Grzegorz, Baj, Michal, Wasik, Dariusz, Szwacki, Nevill Gonzalez, Przybytek, Jacek, Sadowski, Janusz, Sawicki, Maciej, Dziawa, Piotr, and Domagala, Jaroslaw Z.

Abstract

The influence of hydrostatic pressure on the Curie temperature T-C of thin ferromagnetic (Ga,Mn)As layers is studied. New experimental data unambiguously point to both positive and negative pressure-induced changes of Curie temperature. The positive pressure coefficient is observed for samples with relatively high values of T-C and can be quantitatively described by the p-d Zener model of carrier-mediated ferromagnetism within the six-band k . p formalism and the ab initio approach. First-principles calculations of structural, electronic, and magnetic properties of (Ga,Mn)As show that antiferromagnetic coupling of substitutional Mn atoms with interstitial ones may account for a decrease of T-C under pressure in samples having a substantial concentration of interstitial Mn.

Published
2020
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6. Hydrostatic pressure influence on TC in (Ga,Mn)As

Author

Gryglas-Borysiewicz, Marta, primary, Kwiatkowski, Adam, additional, Juszyński, Piotr, additional, Ogorzałek, Zuzanna, additional, Puźniak, Konrad, additional, Tokarczyk, Mateusz, additional, Kowalski, Grzegorz, additional, Baj, Michał, additional, Wasik, Dariusz, additional, Gonzalez Szwacki, Nevill, additional, Przybytek, Jacek, additional, Sadowski, Janusz, additional, Sawicki, Maciej, additional, Dziawa, Piotr, additional, and Domagala, Jaroslaw Z., additional

Published
2020
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7. An effective method for antenna design in field effect transistor terahertz detectors

Author

Zhang, Bo-wen, Yan, Wei, Li, Zhao-feng, Bai, Long, Cywinski, Grzegorz, Yahniuk, Ivan, Szkudlarek, Krzesimir, Skierbiszewski, Czeslaw, Przybytek, Jacek, But, Dmytro b., Coquillat , Dominique, Knap, Wojciech, Yang, Fu-hua, Laboratoire Charles Coulomb (L2C), and Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Computer Science::Emerging Technologies, Physics::Instrumentation and Detectors, terahertz detectors, Physics::Optics, field effect transistors, planar antenna, channel electric field, [PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph]
Abstract

International audience; In the implementation of field effect transistor (FET) terahertz (THz) detectors, the integration of properly designed planar antennas could effectively enhance the coupling efficiencies between the transistors and THz radiation, thus improving the responsivities of THz detectors. A method to design the planar antenna which is based on the simulation of channel electric field at the gate edge of FET is reported here. This method is suitable for the situation where the input impedances of FETs may not be conveniently obtained in the THz regime. The validity of this method in the antenna design is confirmed by the measurements of the fabricated GaN/AlGaN FET THz detectors. The maximum responsivities of the bowtie detector and the dual-dipole detector are obtained at 170.7 GHz (1568.4 V/W) and 124.3 GHz (1047.2 V/W) respectively, which are close to the simulation results of channel electric field at the gate edge of the bowtie detector and the dual-dipole detector.

Published
2018
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11. Noise Features of Metastable Resistivity States in La0.86Ca0.14MnO3 Manganite Single Crystal.

Author

Przybytek, Jacek and Jung, Grzegorz

Subjects
*METASTABLE states, *SINGLE crystals, *MANGANITE, *ELECTRONIC noise, *NOISE, *ELECTRON transport
Abstract

We summarize the long-term electron transport and electronic noise investigations of low-doped La 0. 8 6 Ca 0. 1 4 MnO3 manganite single crystal being in its several, consecutive metastable resistivity states: the pristine high-resistivity one, the low-resistivity, and finally in the high-resistivity metastable state. [ABSTRACT FROM AUTHOR]

Published
2019
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12. Hydrostatic-pressure-induced changes of magnetic anisotropy in (Ga, Mn) As thin films

Author

Gryglas-Borysiewicz, Marta, Juszynski, Piotr, Kwiatkowski, Adam, Przybytek, Jacek, Sadowski, Janusz, Sawicki, Maciej, Tokarczyk, Mateusz, Kowalski, Grzegorz, Dietl, Tomasz, Wasik, Dariusz, Gryglas-Borysiewicz, Marta, Juszynski, Piotr, Kwiatkowski, Adam, Przybytek, Jacek, Sadowski, Janusz, Sawicki, Maciej, Tokarczyk, Mateusz, Kowalski, Grzegorz, Dietl, Tomasz, and Wasik, Dariusz

Abstract

The impact of hydrostatic pressure on magnetic anisotropy energies in (Ga, Mn) As thin films with in-plane and out-of-plane magnetic easy axes predefined by epitaxial strain was investigated. In both types of sample we observed a clear increase in both in-plane and out-of-plane anisotropy parameters with pressure. The out-of-plane anisotropy constant is well reproduced by the mean-field p-d Zener model; however, the changes in uniaxial anisotropy are much larger than expected in the Mn-Mn dimer scenario.

Published
2017
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16. RESULTS OF SURFACE GEOCHEMICAL SURVEY CONDUCTED WITHIN BIECZ ANTICLINE - POLISH OUTER CARPATHIANS.

Author

Twaróg, Anna, Przybytek, Jacek, Ochman, Mateusz, Guzy, Piotr, and Góra, Adrianna

Subjects
*ANTICLINES, *HYDROCARBONS, *HYDROGEN-ion concentration, *FOLDS (Geology), *ORGANIC compounds
Abstract

Light hydrocarbons migrate from the petroleum accumulations to the Earth's surface through faults, fractures and horizons with increased permeability. The occurrence of light hydrocarbons in the near-surface zone forms the basis for the surface geochemical methods. These methods are divided into two groups: direct and indirect. The paper presents the results of "free-gas" method (concentrations of light hydrocarbons and nonhydrocarbon components in the soil gas samples), and also values of pH and calcite content measured in the soil samples. The aim of this paper was to recognize zones of the highest hydrocarbon potential using direct and indirect surface geochemical methods. The studies were carried out along the AB profile within the Biecz Anticline located in the eastern part of the Polish Outer Carpathians. Concentrations of methane, total alkanes C2-C5, total alkenes C2-C4, H2 and CO2 varies in ranges: 1.50 - 9.82 ppm, b.d.l. - 0.347 ppm, b.d.l. - 0.181 ppm, b.d.l. - 621.2 ppm, 0.01 - 3.19 vol.%, respectively. Along the AB profile the values of pH change from 4.34 to 8.14, whereas the values of calcite content vary from 0.04 to 23.14 vol.%. The highest anomalous zone for methane, total alkanes C2-C5, total alkenes C2-C4 and H2 was determined above the anticline core. In this zone we also recorded inverted anomaly of pH, which values were below the calculated background level; whereas the values of calcite content were above the calculated background value. The second, lower anomalous zone for light hydrocarbons and hydrogen is located in the southern limb of the anticline, where the Strzeszyn gas deposit have been discovered. In this area we have observed high similarity between pH and total alkanes C2-C5 anomalies, but we have not noticed anomalous values for calcite content. In the zones where the intensity of hydrocarbons migration is high, the results obtained by the direct and indirect methods confirm the mutual connections between the concentrations of the light hydrocarbons and the values of pH and calcite content. Therefore, indirect method is a reliable supplement for direct method, and both of these surface geochemical methods may be helpful for hydrocarbon exploration. [ABSTRACT FROM AUTHOR]

Published
2018
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