  Deterministic oscillations of current-induced metastable resistivity in
changing voltage have been detected in La$_{0.82}$Ca$_{0.18}$MnO$_3$ single
crystals. At low temperatures, below the Curie point, application of specific
bias procedures switches the crystal into metastable resistivity state
characterized by appearance of pronounced reproducible and random structures in
the voltage dependence of the differential conductivity. In certain bias range
equally spaced broad conductivity peaks have been observed. The oscillating
conductivity has been tentatively ascribed to resonances in a quantum well
within the double tunnel barrier of intrinsic weak-links associated with
twin-like defect boundaries.
