Magnetic imaging of pearl vortices in artificially layered (Ba _0.9Nd_0.1CuO_2+x)_m/(CaCuO ₂)_n systems

The use of scanning SQUID magnetometry to image vortices in ultrathin high temperature superconductor samples was described. The Pearl lenghts in the sample was determined by fits to the vortex images. The SQUID microscope measurements were made at 4.2 K with the sample cooled and imaged in fields of a few mG. It was shown that the in-plane penetration depths inferred from the Pearl lenghts are longer than many bulk cuprates with comparable critical temperatures.