Angular Hysteresis in the Critical Current Density of Laser-Patterned ${\rm REBa}_{2}{\rm Cu}_{3}{\rm O}_{\rm y}$ Films

The transport critical current density J
_c
as a function of applied magnetic field orientation was measured for REBa
₂
Cu
₃
O
_y
(RE:Yb,Y,Dy) films that were line-patterned to make a micro bridge (20 mum x 2 mm) with an etched line-width of 20 mum by laser etching. The angular dependent J
_c
(thetas) curves measured for increasing thetas were found to be different from those measured for decreasing thetas. The angular hysteresis in J
_c
(thetas) appeared more prominently at low temperatures and in low magnetic fields, e.g. at 40 K and at 0.1 T. For similar REBa
₂
Cu
₃
O
_y
films that were plane-patterned by UV photolithography into narrow strips, angular hysteresis was not observed. The hysteresis in J
_c
(thetas) was found to be closely related to the hysteresis in Jc as a function of applied field H, which was also found in line-patterned REBa
₂
Cu
₃
O
_y
films. The origin of the hysteresis in JC(H) of the line-patterned films was examined comparing the experimental results with the results of a theoretical calculation based on a model which assumes that the measured part in the bridge is influenced by the magnetic moment of the electrical terminals part adjacent to it across the etched lines.