  Cuprate superconductors are strongly sensitive materials to disorder and
oxygen stoichiometry; even minute variations of those parameters drastically
change their electronic properties. Here we exploit this characteristic to
engineer a memristive device based on the high-T_C superconductor YBa2Cu3O7-x
(YBCO), in which local changes of the oxygen content and induced disorder are
exploited to produce memory effects. These effects are triggered electrically
in a three-terminal device whose structure is reminiscent of a transistor,
consisting of a YBCO channel and an Al gate. The Al/YBCO interface, which
controls the gate conductance, displays a giant, bipolar, reversible switching
across a continuum of non-volatile conductance states that span over two
Decades. This phenomenon is controlled by the gate voltage magnitude and is
caused by oxygen exchange between YBCO and Al. Concomitantly, the channel shows
a gradual, irreversible superconductor-to-insulator transition that retains a
memory of the power dissipated in the device, and can be explained by induced
bulk disorder. The observed effects, and the understanding of the interplay
between the underlying mechanisms, constitute interesting ingredients for the
design and realization of novel memristors and switches for superconducting
electronics.
