  A mesoscopic ring subject to the Rashba spin-orbit interaction and
sequentially coupled to an interacting quantum dot, in the presence of
Aharonov-Bohm flux, is proposed as a flux tunable tunneling diode. The analysis
of the conductance by means of the nonequilibrium Green's function technique,
shows an intrinsic bistability at varying the Aharonov-Bohm flux when 2U > \pi
\Gamma, U being the charging energy on the dot and \Gamma the effective
resonance width. The bistability properties are discussed in connection with
spin-switch effects and logical storage device applications.
