Electric instability in superconductor-normal conductor ring

Non-linear electrodynamics of a ring-shaped Andreev interferometer (superconductor/normal conductor/ superconductor hybrid structure) coupled to a circuit of the dissipative current is investigated. The current-voltage characteristics (CVC) is demonstrated to be a series of loops with several branches intersecting at the CVC origin. The sensitivity of the transport current J(d) (or the applied voltage V) to a change of the external magnetic flux can be the same as the sensitivity of conventional SQUIDs. Spontaneous arising of coupled non-linear oscillations of the transport current, the Josephson current and the magnetic flux in Andreev interferometers are also predicted and investigated. The frequency of these oscillations can be varied in a wide range, while the maximal frequency can reach omega(max) similar to 10(12) s(-1).