Fourth International Conference on Thin Film Physics and Applications
ABSTRACT We have conducted a systematic study of the effects of laser irradiation on the properti... more ABSTRACT We have conducted a systematic study of the effects of laser irradiation on the properties of crystalline and amorphous YBaCuO thin films obtained by laser deposition. The irradiation experiments were mainly performed with a KrF and XeCl pulsed (25 ns) excimer lasers producing energy densities of the order of 0.1 J/cm2, but we used also Cu vapor green and Ar ion blue lasers with medium power output. In all cases the irradiation produced irreversible changes in the investigated samples. We measured structural, optical and transport properties of the irradiated films. After high dose laser treatment of crystalline (orthorombic) films their superconducting properties as a rule deteriorated, but even small dose was sufficient for a marked improvement of surface smoothness. The response of amorphous films was more complex, dependent on the substrate and relied on the presence of crystalline clusters embedded in the amorphous matrix. X-ray diffraction studies of amorphous films revealed structural transformations caused by the interaction with laser light, and the results of optical spectroscopic measurements lead to interesting conclusions concerning the band structure in the investigated materials. Photon assisted structural transformations are suggested as the possible explanation of the observed effects.
It is shown that the inclusion of junctions characterized by non--sinusoidal current -phase relat... more 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-Tc 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.
Macroscopic quantum coherence effects have been observed in X-band emission from current-biased h... more Macroscopic quantum coherence effects have been observed in X-band emission from current-biased high-Tc films. Two groups of excess emission lines, current stable lines and voltage stable lines, were distinguished in the emission spectra by their different behaviour with changing temperature and magnetic field. The electromagnetic energy was found to be radiated by synchronized clusters composed of only a few intergranular Josephson junctions. Current stable lines are related to coupled two-junction quantum interferometers. Voltage stable lines are due to clusters composed of a few connected single junctions or to a large single junction with pronounced structural fluctuations.
A CT A P HY SIC A P O LO N IC A A No . 5 P r oceedi ng s o f t h e Sy m p o siu m o n Syn chr otr... more A CT A P HY SIC A P O LO N IC A A No . 5 P r oceedi ng s o f t h e Sy m p o siu m o n Syn chr otr on Cr y st all ogr ap hy, Kr y n ica, Po l an d 200 1 X -r ay C h ara ct er izati on of Fi l m s Form ed by P u lsed L aser De p osition on C old Su b strate s from Y B aC u O T ar gets J .B. P e¤k a a , W. Paszk ow icz a , P. Gi er¤ owsk i a , S.J. Le wando w sk i a , M. Zi eli ¥sk i a , S. Ba r ban era b and M. Kn app c a In st it ut e of P hysi cs, Po l i sh Ac ademy of Sciences al . Lo tni k §w 32/ 46, 02-668 W arsaw, Po l and b Insti tute of Sol i d State El ectro ni cs CN R vi a Ci neto Romano 42, 00-15 6 R om e, Ita l y c D epa rtm ent of Ma teri al s Science, Darm stadt Uni versi ty of T echnology Petersenstr. 23, 6 4287 Darm stadt, G ermany
We have demonstrated that the alkaline-rare-earth aluminates (K~NiF4-type perovskites) are an exc... more We have demonstrated that the alkaline-rare-earth aluminates (K~NiF4-type perovskites) are an excellent choice as the substrate material for the growth of high-Tc thin films suitable for microwave and far-infrared applications. The CaNdA104, and SrLaAlOq single crystals have been grown by Czochralski pulling and fabricated into the form of (001) oriented wafers. The Y-Ba-Cu-0 and Bi-Sr-Ca-Cu-0 films deposited on these substrates by a single-target magnetron sputtering exhibited very good superconducting and structural properties. Dielectric properties of the CaNdAlO4, and SrLaAlOq crystals at submillimeter-wave frequencies are also presented and compared to our measurements of the other materials most commonly used as substrates for deposition of high-Tc films.
Fourth International Conference on Thin Film Physics and Applications
ABSTRACT We have conducted a systematic study of the effects of laser irradiation on the properti... more ABSTRACT We have conducted a systematic study of the effects of laser irradiation on the properties of crystalline and amorphous YBaCuO thin films obtained by laser deposition. The irradiation experiments were mainly performed with a KrF and XeCl pulsed (25 ns) excimer lasers producing energy densities of the order of 0.1 J/cm2, but we used also Cu vapor green and Ar ion blue lasers with medium power output. In all cases the irradiation produced irreversible changes in the investigated samples. We measured structural, optical and transport properties of the irradiated films. After high dose laser treatment of crystalline (orthorombic) films their superconducting properties as a rule deteriorated, but even small dose was sufficient for a marked improvement of surface smoothness. The response of amorphous films was more complex, dependent on the substrate and relied on the presence of crystalline clusters embedded in the amorphous matrix. X-ray diffraction studies of amorphous films revealed structural transformations caused by the interaction with laser light, and the results of optical spectroscopic measurements lead to interesting conclusions concerning the band structure in the investigated materials. Photon assisted structural transformations are suggested as the possible explanation of the observed effects.
It is shown that the inclusion of junctions characterized by non--sinusoidal current -phase relat... more 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-Tc 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.
Macroscopic quantum coherence effects have been observed in X-band emission from current-biased h... more Macroscopic quantum coherence effects have been observed in X-band emission from current-biased high-Tc films. Two groups of excess emission lines, current stable lines and voltage stable lines, were distinguished in the emission spectra by their different behaviour with changing temperature and magnetic field. The electromagnetic energy was found to be radiated by synchronized clusters composed of only a few intergranular Josephson junctions. Current stable lines are related to coupled two-junction quantum interferometers. Voltage stable lines are due to clusters composed of a few connected single junctions or to a large single junction with pronounced structural fluctuations.
A CT A P HY SIC A P O LO N IC A A No . 5 P r oceedi ng s o f t h e Sy m p o siu m o n Syn chr otr... more A CT A P HY SIC A P O LO N IC A A No . 5 P r oceedi ng s o f t h e Sy m p o siu m o n Syn chr otr on Cr y st all ogr ap hy, Kr y n ica, Po l an d 200 1 X -r ay C h ara ct er izati on of Fi l m s Form ed by P u lsed L aser De p osition on C old Su b strate s from Y B aC u O T ar gets J .B. P e¤k a a , W. Paszk ow icz a , P. Gi er¤ owsk i a , S.J. Le wando w sk i a , M. Zi eli ¥sk i a , S. Ba r ban era b and M. Kn app c a In st it ut e of P hysi cs, Po l i sh Ac ademy of Sciences al . Lo tni k §w 32/ 46, 02-668 W arsaw, Po l and b Insti tute of Sol i d State El ectro ni cs CN R vi a Ci neto Romano 42, 00-15 6 R om e, Ita l y c D epa rtm ent of Ma teri al s Science, Darm stadt Uni versi ty of T echnology Petersenstr. 23, 6 4287 Darm stadt, G ermany
We have demonstrated that the alkaline-rare-earth aluminates (K~NiF4-type perovskites) are an exc... more We have demonstrated that the alkaline-rare-earth aluminates (K~NiF4-type perovskites) are an excellent choice as the substrate material for the growth of high-Tc thin films suitable for microwave and far-infrared applications. The CaNdA104, and SrLaAlOq single crystals have been grown by Czochralski pulling and fabricated into the form of (001) oriented wafers. The Y-Ba-Cu-0 and Bi-Sr-Ca-Cu-0 films deposited on these substrates by a single-target magnetron sputtering exhibited very good superconducting and structural properties. Dielectric properties of the CaNdAlO4, and SrLaAlOq crystals at submillimeter-wave frequencies are also presented and compared to our measurements of the other materials most commonly used as substrates for deposition of high-Tc films.
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Papers by Janusz Konopka