Patterned Electron Beam Exposures of YBCO - Towards Local Control of Doping

Local control of dopant profiles and ordered doping in high Tc superconductors have the potential to greatly increase the transition temperature, Tc. We report on experiments where we used focused electron beams to locally modulate the oxygen dopant concentration in commercial YBCO films (100 nm on LaAlO3). Patterned exposure of YBCO samples to 10 keV electrons and fluences in the 1020 e-/cm2 range led to increases of Tc of ∼0.4 K, comparable to earlier reports from broad beam exposures in a similar fluence regime. We discuss our results in relation to concepts of local oxygen depletion and chain ordering induced by ionizing radiation and outline possible processing paths to implement a form of modulation doping in YBCO by patterning with intense, short excitation pulses (e. g. of MeV protons).