thin films and manipulation of their electrical properties*

Multiferroic BiFeO₃ thin films can allow electrical control of magnetism at room temperature and potentially magnetic control of electric polarization. We have investigated the use of adsorption-controlled molecular-beam epitaxy to grow BiFeO₃ thin films, as an alternative to the more commonly-used pulsed laser deposition or sputtering. We demonstrate unprecedentedly long-range domain periodicity of domain walls in commensurately strained BiFeO₃/SrRuO₃/DyScO₃(110)_o epitaxial heterostructures. We observe two domain variants under piezoresponse force microscopy (PFM), which form alternating 140-nm-wide striped domains. Conductive AFM shows that the domain walls exhibit enhanced conductivity relative to the bulk and electrical rectification. For applications, ion irradiation can be used to reduce the through-film leakage without increasing the coercive field for ferroelectric switching. Doping with lanthanum is effective in reducing the strength of ferroelectric polarization, a necessary step to enable magnetic control of the polarization.