  Oxygen migration in tantalum oxide, a promising next-generation storage
material, is studied using in-operando x-ray absorption spectromicroscopy and
is used to microphysically describe accelerated evolution of conduction channel
and device failure. The resulting ring-like patterns of oxygen concentration
are modeled using thermophoretic forces and Fick diffusion, establishing the
critical role of temperature-activated oxygen migration that has been under
question lately.
