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1

Dynamics of the Josephson Multi-Junction Systems with Junctions Characterized by Non-Sinusoidal Current - Phase Relationship

100%

Abal'osheva I., Lewandowski S.

Acta Physica Polonica A

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2004

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vol. 106

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issue 5

687-691

EN

It is shown that the inclusion of junctions characterized by non-sinusoidal current - phase relationship in the systems composed of multiple Josephson junctions - results in the appearance of additional system phase states. Numerical simulations and stability considerations confirm that these phase states can be realized in practice. Moreover, spontaneous formation of the grain boundary junctions in high-T_c superconductors with non-trivial current-phase relations due to the d-wave symmetry of the order parameter is probable. Switching between the phase states of multiple grain boundary junction systems can lead to additional 1/f noise in high-T_c superconductors.

2

Inhomogeneous Magnetic Field Penetration in Superconducting Niobium Films

71%

Abal'osheva I., Abal'oshev A., Cieplak M., Zhu L., Chien C.

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issue 2

396-398

EN

The peculiarities of magnetic field penetration in the form of fingering or dendritic instabilities are studied by magneto-optical technique in the niobium films of different thickness. It is observed that the reduction of Nb film thickness reduces the threshold field for instabilities, in agreement with the theoretical predictions. In addition, it is shown that the silver overlayer deposited on the top of Nb film leads also to the enhancement of instabilities, in marked contrast to the effect of gold or aluminum overlayers, which are known to suppress instabilities.

3

Effect of the In-Plane Epitaxial Mismatch between the Substrate and the Film on the Properties of YBa_2Cu_3O_{7-δ} Films

61%

Abal'osheva I., Cieplak M., Adamus Z., Berkowski M., Domukhovski V., Aleszkiewicz M.

Acta Physica Polonica A

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2006

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vol. 109

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issue 4-5

549-554

EN

We study the effect of the in-plane epitaxial mismatch between the substrate and the film on the crystallographic structure and the transport properties of YBa_2Cu_3O_{7-δ} superconducting films of thicknesses ranging between 600 and 3000Å. The films are grown by pulsed laser deposition on the new type of single-crystalline substrates prepared by Czochralski method, with the chemical formula (SrAl_{0.5}Ta_{0.5}O_3)_{0.7}(CaAl_{0.5}Ta_{0.5}O_3)_{0 .1}(LaAlO_3)_{0.2}. We find that superconducting properties of the samples are excellent, and generally they improve with increasing of the film thickness as a result of improved structural ordering. We also investigate the influence of the film thickness on the behavior of the critical current densities.

4

Study of Excimer Laser Irradiation Effects on Properties of Crystalline YBaCuO Thin Films

61%

Abal'oshev A., Abal'osheva I., Lewandowski S., van der Beek C., Konczykowski M., Rizza G., Barbanera S.

Acta Physica Polonica A

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2004

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vol. 106

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issue 5

681-685

EN

The influence of UV laser irradiation on the physical properties of epitaxial YBa_2Cu_3O_{7-δ} thin (<1μm) films fabricated by laser ablation was studied. The samples were irradiated by pulsed excimer laser beam at different incident energy densities E_{ir}≤130 mJ/cm^2, i.e. 2-3 times below the ablation threshold of YBaCuO. The analysis of the sample cross-section using transmission electron microscope shows that such irradiation forms a disordered layer on the top of the crystalline film. Sample surface amorphization was observed also by atomic force microscope. Due to strong UV irradiation absorption in YBaCuO this surface layer acts like a protective cover for the sample interior. Only a small reduction of superconducting critical temperature T_c was observed. Both transport measurements in normal state and magneto-optical studies in superconducting state indicate that between the disordered layer and the bottom non-modified part of the film there exists a wide transitional region with reduced carrier concentration.

5

Tunneling Conductivity of Manganites with Negative Magnetoresistance

61%

Medvedev Y., Tarenkov V., Svistunov V., Abaloshev A., Abalosheva I., Lewandowski S.

Acta Physica Polonica A

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2000

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vol. 97

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issue 5

827-830

EN

Tunneling investigations of ferromagnetic La_{0.6}Sr_{0.4}MnO_{3} ceramic samples showing negative magnetoresistance effect were carried out in two types of junctions: symmetric "break junctions" and asymmetric ceramics-insulator-metal junctions. The results are consistent with the presence of small ferromagnetic clusters in the insulating barriers of both types of junctions and suggest a two-phase state realized by impurity mechanism of phase separation.

6

Optimization of the Superconducting Properties of Laser Ablated YBa_2Cu_3O_{7-δ} Films on CeO_2-Buffered Sapphire

52%

Abal'osheva I., Zaytseva I., Aleszkiewicz M., Syryanyy Y., Gierłowski P., Abal'oshev O., Bezusyy V., Cieplak M.

Acta Physica Polonica A

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2012

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vol. 121

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issue 4

805-807

EN

We use pulsed laser deposition to grow YBa_2Cu_3O_{7-δ} (YBCO) superconducting films for microwave applications. The films are grown on R-cut sapphire substrates, with CeO_2 buffer layers, which are re-crystallized at high temperature prior to YBCO growth. Using the atomic force microscopy (AFM) and X-ray diffractometry we determine the optimal temperature for recrystallization (1000°C) and the optimal buffer layer thickness (30 nm). The properties of YBCO films of various thickness, grown on the optimized CeO_2 buffer layers, are studied using several methods, including AFM, magnetooptical imaging, and transport experiments. The YBCO film roughness is found to increase with the increasing film thickness, but the magnetic flux penetration in the superconducting state remains homogeneous. The superconducting parameters (the critical temperature and the critical current density) are somewhat lower than the similar parameters for YBCO films deposited on mono-crystalline substrates.

7

Growth and Characterization of YBa_2Cu_3O_{7-δ} Films Deposited by Laser Ablation on CeO_2-Buffered Sapphire

52%

Abal'osheva I., Zaytseva I., Aleszkiewicz M., Malinowski A., Bezusyy V., Syryanyy Y., Gierłowski P., Abal'oshev O., Kończykowski M., Cieplak M.

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vol. 126

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issue 4a

A-69-A-73

EN

In this work we study the growth, by pulsed laser deposition, of YBa_2Cu_3O_{7-δ} (YBCO) films on the CeO_2-buffered R-cut sapphire substrates, with the buffer layer recrystallized prior to the deposition of superconductor. We find that the superconducting critical temperature and the critical current density of the films are very close to similar parameters for the YBCO films grown on lattice-matched single crystalline substrates. It appears that the structural defects in the buffer layer affect the microstructure of YBCO films, resulting in high values of the critical current density, suitable for applications.

8

Magnetic Properties of FeSeTe Compound Crystallized from Liquid Phase

52%

Lewandowski S., Berkowski M., Tarenkov V., D'yachenko A., Abal'oshev A., Abal'osheva I., Gawryluk D., Domukhovski V., Sidorov S., Boichenko D.

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issue 2

289-291

EN

We report on measurements of samples with nominal composition FeSe_{0.5}Te_{0.5}, crystallized by the Bridgman method. Magnetic and transport properties of the samples were examined. The measurements confirm the coexistence of ferromagnetism and superconductivity below the superconducting transition temperature. The ferromagnetic contribution to magnetization, estimated at 10%, might be caused by the presence of ferrimagnetic Fe_7Se_8, which occupies about 10% of sample volume. From the Andreev spectroscopy we found superconducting energy gap Δ = 2.6 meV at T = 4.2 K, and from magnetization measurements the critical temperature T_c = 15.8 K. The critical current density in magnetic field H = 4 kOe, determined from magnetization measurements, is j_c = (1-2) × 10^4 A/cm^2 and weakly depends on magnetic field intensity.

Refine search results

Dynamics of the Josephson Multi-Junction Systems with Junctions Characterized by Non-Sinusoidal Current - Phase Relationship

Inhomogeneous Magnetic Field Penetration in Superconducting Niobium Films

Effect of the In-Plane Epitaxial Mismatch between the Substrate and the Film on the Properties of YBa_2Cu_3O_{7-δ} Films

Study of Excimer Laser Irradiation Effects on Properties of Crystalline YBaCuO Thin Films

Tunneling Conductivity of Manganites with Negative Magnetoresistance

Optimization of the Superconducting Properties of Laser Ablated YBa_2Cu_3O_{7-δ} Films on CeO_2-Buffered Sapphire

Growth and Characterization of YBa_2Cu_3O_{7-δ} Films Deposited by Laser Ablation on CeO_2-Buffered Sapphire

Magnetic Properties of FeSeTe Compound Crystallized from Liquid Phase