Conductivity oscillations in current-induced metastable states in low-doped manganite single crystals

Deterministic oscillations of current-induced metastable resistivity in changing voltage have been detected in La_0.82Ca_0.18MnO₃ single crystals. At low temperatures, below the Curie point, application of specific bias procedures switches the crystal into a metastable resistivity state characterized by the appearance of pronounced reproducible and random structures in the voltage dependence of the differential conductivity. In a 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 twinlike defect boundaries.