Anomalies in the gadolinium doped ceria resistance below 90 K

The resistance of the free standing Ce0.8Gd0.2O1.9 membranes was investigated for a wide range of temperatures, frequencies and various applied bias voltages. The electrical resistance of the membranes grew when the samples were cooled down to 90 K, as is expected with dielectric materials. An unexpected monotonous decreasing of the resistance was observed below 90 K with a reduction of about 15–25% when samples were cooled from 90 K to 40 K. In the same temperature range a non-linear (asymmetrical, with a hysteretic loop) dependence of the resistance on an applied bias was observed. The samples “remembered” the maximum applied bias, in the same way as memristor remembers a traversed charge; that leads to disappearing of the hysteresis, which was observed in the electrical parameters of samples under bias treatment, after first applying the bias and its appearance after the maximum of the applied bias increasing. These effects are explained by the oxygen vacancies stabilization, asymmetry due to electric field difference near two interfaces, and vacancies rearrangement under applied bias.