Bistable memory effect in chromium oxide junctions

Magnetotransport properties of granular CrO2 /Cr2O3 films made of CrO2 crystals covered by 12 nm native insulating Cr2O3 are presented. Electrical properties of a limited number of grains measured in series and parallel (10 to 15 grains) reveal intergrain tunneling characteristics. At lowest temperatures, a well pronounced zero bias anomaly indicates that impurities in the junctions block the electronic flow. Hysteresis in the IV curves are observed at intermediate temperatures on zero-field cooled samples. Changing the polarity of a short excitation pulse (100ns) of amplitude smaller than 1 V triggers a change in the zero-bias resistance by 10-50%. These states are stable and well reproducible in the temperature interval ranging from 100K to 250K. Applying an external magnetic field cancels the IV hysteresis. The resistance of the devices in the kΩ range, the potential high-speed for writing and reading the resistance sate, make these systems interesting candidates for magnetic non-volatile memories.