A. Moto et al., Terahertz radiation imaging of vortex penetration into YBCO thin films with and without ordered arrays of antidots, IEICE TR EL, E84C(1), 2001, pp. 67-73
Terahertz radiation imaging has been employed to diagnose the supercurrent
and vortex distribution in high-T-c superconductive thin film strips. We ob
serve them in the YBCO films patterned into the strip with and without orde
red arrays of small antidots. Comparison with theoretically expected distri
bution reveals that the present technique can provide a powerful tool for t
he noncontact, nondestructive, and free-space evaluation of the supercurren
t and the vortex distribution with good quantitative agreement. The effect
of the antidot formation in the strips is explained by the decrease of the
effective critical current. The remanent state after removal of the relativ
ely large magnetic field cannot be explained by the conventional model for
the superconductive thin films and the discrepancy is more notable in the a
ntidot formed area.