Institute of Electronic Engineering and Industrial Technologies ASM

Chişinău, Moldova

Institute of Electronic Engineering and Industrial Technologies ASM

Chişinău, Moldova

Time filter

Source Type

Koparan E.T.,Karadeniz Technical University | Surdu A.,Institute of Electronic Engineering and Industrial Technologies ASM | Sidorenko A.,Institute of Electronic Engineering and Industrial Technologies ASM | Yanmaz E.,Karadeniz Technical University
Journal of Superconductivity and Novel Magnetism | Year: 2012

MgB2 film with a thickness of about 600 nm was deposited on the MgO (100) single crystal substrate using a 'two-step' synthesis technique. First, deposition of boron thin film was carried out by rf magnetron sputtering on MgO substrates and followed by a post deposition annealing at 850°C in magnesium vapor. The upper critical field Hc2 has been estimated from temperature dependences of resistivity curves in both directions of the magnetic fields perpendicular and parallel to the c-axis. Resistivity measurements of the film were performed using a standard fourprobe method under different magnetic fields up to 70 kOe in zero fields cooling regime. The upper critical magnetic field Hc2(0) at T = 0 K for 90 % of Rn was calculated by the extrapolation Hc2(T ) to the temperature T = 0 K. The results showed that Hc2 ab(0) and Hc2 δ c(0) was found to be around 22 T and 18 T, respectively. Using extracted data, the zero-temperature coherence lengths and field anisotropy ratio were calculated. In order to determine the activation energy of thermally activated flux flow of the film, Arrhenius law was taken into account. © Springer Science+Business Media, LLC 2012.


Taylan Koparan E.,Karadeniz Technical University | Taylan Koparan E.,Institute of Electronic Engineering and Industrial Technologies ASM | Surdu A.,Institute of Electronic Engineering and Industrial Technologies ASM | Awawdeh A.,Institute of Electronic Engineering and Industrial Technologies ASM | And 2 more authors.
Journal of Superconductivity and Novel Magnetism | Year: 2012

MgB 2 thin films were fabricated on MgO (100) single crystal substrates. First, deposition of boron was performed by rf magnetron sputtering on MgO substrates and followed by a post deposition annealing at 850 °C in magnesium vapor. In order to investigate the effect of FeO nanoparticles on magnetic properties of MgB 2 thin films, the films were coated with different concentrations of FeO nanoparticles by spin coating process. The magnetic field dependence of the critical current density J c was calculated from theM-H loops and also magnetic field dependence of the pinning force density fp(b) was determined for the films containing different concentrations of FeO nanoparticles. The values of the critical current density J c in zero field at 5 K was found to be around 1 × 106 A/cm 2 for pure MgB 2 film, 1.4 × 106 for MgB 2 film coated with 25 %, 7.2 × 105 for MgB 2 film coated with 33 %, 9.1×105 forMgB 2 film coated with 50% and 1.1 × 106 A/cm 2 for MgB 2 film coated with 100 %. It was found that the film coated with 25 % FeO nanoparticles has slightly enhanced critical current density and it can be noted that especially the film coated with 25 % FeO became stronger in the magnetic field. The films coated with FeO were successfully produced and they indicated the presence of artificial pinning centers created by FeO nanoparticles. The superconducting transition temperature of the film coated with 25 % FeO nanoparticles was determined by moment-temperature (M-T ) measurement to be 34 K which is 4 K higher than that of the pure film. © Springer Science+Business Media, LLC 2012.


Palistrant M.,Institute of Applied Physics ASM | Surdu A.,Institute of Electronic Engineering and Industrial Technologies ASM | Petrenko P.,Institute of Applied Physics ASM | Sidorenko A.,Institute of Applied Physics ASM | Ursu V.,Institute of Electronic Engineering and Industrial Technologies ASM
Fizika Nizkikh Temperatur (Kharkov) | Year: 2011

Main theoretical results of the microscopic two-band theory for the temperature dependence of the upper critical fields Hc2(ab) and Hc2(c) in pure two-band systems like MgB2 are presented. The analytical solutions for the upper critical fields near the superconducting transition temperature and near the zero temperature were transformed to be directly compared with experimental data. The experimental Hc2(ab) and Hc2(c) temperature dependences of textured MgB2 films near the superconducting transition temperature were measured and compared with the respective theoretical formulas. The results of this theoretical approach were also compared with earlier published experimental data of other authors. The chosen method allows obtaining an accurate match between the theoretical expressions and experimental results. © M. Palistrant, A. Surdu, V. Ursu, P. Petrenko, and A. Sidorenko, 2011.

Loading Institute of Electronic Engineering and Industrial Technologies ASM collaborators
Loading Institute of Electronic Engineering and Industrial Technologies ASM collaborators