  The present-day nanodevice dimensions continuously shrink, with the aim to
prolong Moore's law. As downsizing meticulously persists, undesirable dynamic
defects, which cause low-frequency noise and structural instability, play
detrimental roles on limiting the ultimate performance and reliability of
miniaturized devices. A good understanding and a meaningful control of the
defect kinetics then become fundamental and urgent issues. Here we report
observations of thermally activated atomic defect motion as well as
nanocrystalline defect motion through electrical noise processes in metallic
RuO$_2$ rutile nanowires around room temperature. First, we extract the energy
distribution function and the number density of mobile atomic defects (oxygen
vacancies). Second, we obtain the geometrical size, grain-boundary bonding
strength, and relaxation times of dynamic nanocrystallites. Our results show
clearly a powerful probe for effective and noninvasive characterizations of
nanostructures and nanomaterials for which quantitative information about
mechanical hardness, breakdown current density, and/or resistance noise is
essential.
