M. Yamashita et al., Supercurrent distribution in YBCO strip lines under bias current and magnetic fields observed by THz radiation imaging, PHYSICA C, 355(3-4), 2001, pp. 217-224
We have observed the supercurrent distribution in YBa2Cu3O7-delta (YBCO) st
rip lines under bias current and magnetic fields using terahertz (THz) radi
ation imaging. By mapping the amplitude of the THz pulses, which are emitte
d from the YBCO strip lines excited by ultrashort optical pulses, the super
current distribution is visualized. It is found that the spatial resolution
of the obtained image depends on the excitation laser spot size. Irreversi
bility of the current distribution between increasing and decreasing the bi
as current is observed, which is semiquantitatively explained by the theore
tical calculation based on the Bean critical state model for thin films. Th
is technique can be a unique and powerful tool for the noncontact evaluatio
n of the supercurrent distribution in high-T-c superconducting thin films.
(C) 2001 Elsevier Science B.V. All rights reserved.