Abstract: Ferroic materials and methods for diverse applications including nanoscale memory, logic and photovoltaic devices are described. In one aspect, ferroic thin films including insulating domains separated by conducting domain walls are provided, with both the insulating domains and conducting domain walls intrinsic to the ferroic thin films. The walls are on the order of about 2 nm wide, providing virtually two dimensional conducting sheets through the insulating material. Also provided are methods of writing, reading, erasing and manipulating conducting domain walls. According to various embodiments, logic and memory devices having conducting domain walls as nanoscale features are provided. In another aspect, ferroic thin films having photovoltaic activity are provided. According to various embodiments, photovoltaic and optoelectronic devices are provided.