Memristors are among the most promising elements for modern microelectronics,
having unique properties such as quasi-continuous change of conductance and
long-term storage of resistive states. However, identifying the physical
mechanisms of resistive switching and evolution of conductive filaments in such
structures still remains a major challenge. In this work, aiming at a better
understanding of these phenomena, we experimentally investigate an unusual
effect of enhanced conductive filament stability in memristors with copper
filaments under the applied voltage and present a simplified theoretical model
of the effect of a quantum current through a filament on its shape. Our
semi-quantitative, continuous model predicts, indeed, that for a thin filament,
the "quantum pressure" exerted on its walls by the recoil of charge carriers
can well compete with the surface tension and crucially affect the evolution of
the filament profile at the voltages around 1V. At lower voltages, the quantum
pressure is expected to provide extra stability to the filaments supporting
quantized conductance, which we also reveal experimentally using a novel
methodology focusing on retention statistics. Our results indicate that the
recoil effects could potentially be important for resistive switching in
memristive devices with metallic filaments and that taking them into account in
rational design of memristors could help achieve their better retention and
plasticity characteristics.Comment: version accepted for publication in Phys. Rev. Applied, including
improved statistic