arXiv subjects

D. T. Verebelyi

Publications and source records attributed to D. T. Verebelyi.

3 recordsLinked to original sources

arXiv2005

Anisotropic, non-monotonic behavior of the superconducting critical current in thin YBa2Cu3O7-d films on vicinal SrTiO3 surfaces

The critical current density of epitaxial YBCO films grown on vicinal SrTiO3 substrates was investigated by electrical transport measurements along and across the steps of the SrTiO3 surface for a range of temperatures of 10 K to 85 K and in applied magnetic fields varying from 0 to 14 T. For vicinal angles of 4 and 8 degrees, we found evidence of enhanced pinning in the longitudinal direction at low magnetic fields for a wide region of temperatures and attribute this phenomenon to anti-phase boundaries in the YBCO film. The transverse Jc data showed a peak in the Jc(H) curve at low magnetic fields, which was explained on the basis of magnetic interaction between Abrikosov and Abrikosov-Josephson vortices. The in-plane Jc anisotropy observed for vicinal angles of 0.4 degrees was reversed with respect to the 8 degree and 4 degree samples. This phenomenon was interpreted on the basis of strain induced in the YBCO film by the stepped substrate's surface.

cond-mat.supr-con↗

arXiv2003

Self-organized current transport through low angle grain boundaries in YBa$_2$Cu$_3$O$_{7-δ}$ thin films, studied magnetometrically

The critical current density flowing across low angle grain boundaries in YBa$_2$Cu$_3$O$_{7-δ}$ thin films has been studied magnetometrically. Films (200 nm thickness) were deposited on SrTiO$_3$ bicrystal substrates containing a single [001] tilt boundary, with angles of 2, 3, 5, and 7 degrees, and the films were patterned into rings. Their magnetic moments were measured in applied magnetic fields up to 30 kOe at temperatures of 5 - 95 K; current densities of rings with or without grain boundaries were obtained from a modified critical state model. For rings containing 5 and 7 degree boundaries, the magnetic response depends strongly on the field history, which arises in large part from self-field effects acting on the grain boundary.

cond-mat.supr-con↗

arXiv2001

Critical Current Density of YBa{2}Cu{3}O{7-d} Low-Angle Grain Boundaries in Self-Field

A study has been perfomed on the superconducting critical current density J_{c} flowing across low angle grain boundaries in epitaxial thin films of YBa{2}Cu{3}O{7-d} (YBCO). The materials studied were dual grain boundary rings deposited on SrTiO{3} and containing 2, 3, 5 and 7 degree tilt boundaries. The current density in self-field was determined by magnetometric methods at temperatures from 5 K to T_c. We conclude that at the higher temperatures of coated conductor applications, there is limited potential for improving J_{c} by reducing the grain boundary angle below about 3 degrees.

cond-mat.supr-con↗