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Bruynseraede, Y., E. Osquiguil, M. Maenhoudt, B. Wuyts, G. Nieva, J. Guimpel, D. Lederman, and I. K. Schuller. "Enhancement of Superconductivity by Photoexcitation." The Vortex State (NATO Science Series C: Mathematical and Physical Sciences) 438 (1994): 303–312.
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Dhalle, M., W. Boon, E. Osquiguil, C. Van Haesendonck, Y. Bruynseraede, J. Kwarciak, and O. Van Der Biest. "Correlation between critical current and resistivity in YBa2Cu3O7." Physica C: Superconductivity and its applications 185-189, no. PART 4 (1991): 2447–2448.
Abstract: Critical current versus temperature measurements were carried out in ceramic YBa2Cu3O7 samples. The samples were all prepared using the same sintering procedure, but starting from powders obtained by different wet and dry methods. All samples showed a linear Jc vs. T behaviour, typical of Josephson weak-link coupling, with a slope that depends on the preparation method. Using the Ambegaokar-Baratoff relation for Jc, the difference in slopes can be attributed to a change in the characteristic value of the junction resistance. This value turns out to be clearly correlated with the resistivity in the normal state.
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Fullerton, E. E., D. M. Kelly, J. Guimpel, I. K. Schuller, and Y. Bruynseraede. "Roughness and giant magnetoresistance in Fe/Cr superlattices." Physical Review Letters 68, no. 6 (1992): 859.
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Gao, Z. X., I. Heyvaert, B. Wuyts, E. Osquiguil, C. V. Haesendonck, and Y. Bruynseraede. "Evidence for a “brick wall” microstructure in epitaxial YBa 2Cu3Ox films." Applied Physics Letters 65, no. 6 (1994): 770–772.
Abstract: We have measured the in-plane (ab plane) critical current density J c in sputtered, c-axis oriented YBa2Cu3O x films as a function of the oxygen content x. The important reduction of Jc with decreasing x can be explained in terms of a “brick wall” microstructure, where the critical current density is dominated by the coupling strength (along the c axis) between the superconducting CuO 2 planes. Scanning tunneling microscopy images of the film surfaces are consistent with the presence of the brick wall structure, which apparently results from the overlap between terraces belonging to adjacent spiral-shaped islands.
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Gao, Z. X., E. Osquiguil, M. Maenhoudt, B. Wuyts, S. Libbrecht, and Y. Bruynseraede. "3D-2D dimensional crossover in YBa2Cu3O7 films." Physical Review Letters 71, no. 19 (1993): 3210–3213.
Abstract: We show that, in fully oxidized YBa2Cu3O7 c-axis oriented films, the changes induced in the angular and field dependence of the magnetoresistivity ?ab by increasing the temperature towards Tc are similar to those caused by a lowering in oxygen content. This remarkable behavior can be interpreted as due to a crossover from a three-dimensional to a two-dimensional system as T approaches Tc. Moreover, our critical current data mimic the behavior observed by Qi Li et al. in YBa2Cu3O7/(PrxY1-x)Ba2Cu3O7 multilayers, suggesting the possibility that chain planes are superconducting.
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Griessen, R., Wen Hai-Hu, A. J. J. Van Dalen, B. Dam, J. Rector, H. G. Schnack, S. Libbrecht, E. Osquiguil, and Y. Bruynseraede. "Evidence for mean free path fluctuation induced pinning in YBa2Cu3O7 and YBa2Cu4O8 films." Physical Review Letters 72, no. 12 (1994): 1910–1913.
Abstract: The critical current jc and the pinning energy Uc have been determined for three types of yttrium-based superconducting films from current js and dynamic relaxation Q=d lnjs/d ln(dB/dt) data by means of the generalized inversion scheme. For B<2 T and T<80 K the temperature dependence of jc and Uc for all films is found to be in excellent agreement with a model of single vortices pinned by randomly distributed weak pinning centers via spatial fluctuations of the charge carrier mean free path. Pinning due to spatial fluctuations of Tc is not observed.
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Guimpel, J., P. Høghøj, I. K. Schuller, J. Vanacken, and Y. Bruynseraede. "Scaling of the irreversibility line in a low temperature superconducting oxide." Physica C: Superconductivity 175, no. 1-2 (1991): 197–201.
Abstract: We have studied the critical field and irreversibility line on the magnetization of the ceramic oxide LiTi2O4. The irreversibility line scales with the critical field while the coherence length of the material changes by a factor of two. This universal behavior indicates that the origin of the irreversibility line does not depend on extrinsic factors and relies solely on the intrinsic superconducting parameters of the material.
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Heyvaert, I., E. Osquiguil, C. Van Haesendonck, and Y. Bruynseraede. "Etching of screw dislocations in YBa2Cu3O7 films with a scanning tunneling microscope." Applied Physics Letters 61, no. 1 (1992): 111–113.
Abstract: We report on the systematic unrolling of screw dislocations with the scanning tunneling microscope at the surfaces of sputtered, c-axis oriented YBa2Cu3O7 films. The etching is dominated by field induced evaporation and not by mechanical milling of the surface. The process also enables the controlled drawing of nanometer scale grooves on the film surface.
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Hoffmann, A., G. Nieva, J. Guimpel, Y. Bruynseraede, J. Santamaria, D. Lederman, and I. K. Schuller. "Comment on “Photoemission study of YBa2Cu3Oy thin films under light illumination”." PHYSICAL REVIEW LETTERS 97, no. 11 (2006): 119701.
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Lederman, D., J. Hasen, I. K. Schuller, E. Osquiguil, and Y. Bruynseraede. "Photoinduced superconductivity and structural changes in high temperature superconducting films." Applied Physics Letters 64, no. 5 (1994): 652–654.
Abstract: The illumination of PryGd1-yBa2Cu 3Ox semiconducting and superconducting thin films increases their critical temperatures and decreases their normal state resistivities if and only if the films are oxygen deficient. Moreover, these changes are enhanced near the Pr-induced metal-insulator transition. Light also causes a contraction of the c-axis in YBa2Cu3Ox which is correlated with the observed photoinduced resistivity changes. These changes are similar to those observed when oxygen-deficient YBa 2Cu3Ox is enriched with oxygen or annealed at room temperature after quenching from high temperatures.
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