Impedance study of reproducible switching memory effect

The reproducible switching and memory effect in thin film colossal magnetoresistive (CMR) materials has been further studied. A resistive memory device was made in a sandwich structure comprised of Au or Pt top electrode on Pr_0.17Ca_0.3MnO₃ (PCMO) on Pt/LaAIO₃(100) (LAO), on Pt/TiN/SiO₂/Si, and on YBa₂Cu₃O_7-δ (YBCO) on LaAIO3 (100) substrates. In these samples, polycrystalline PCMO films were deposited on polycrystalline Pt films, and (101) ordered PCMO films were epitaxially grown on c-oriented YBCO crystalline films. Both PCMO and YBCO films were deposited by pulse laser deposition (PLD). The top Au electrode was made by dc-sputtering, and in the case of Pt top and bottom electrodes they were deposited by e-beam evaporation. We have characterized the temperature dependence of the device resistance change R(T) upon electric pulse switching. We have also measured the impedance spectroscopy Z(T,Ω) of the device in the temperature range of 77K to 300K and the frequency range from 10 to I06 Hz for both the low- resistance and high-resistance states of the resistive memory device. The influence of intrinsic film defects on switching and fatigue properties of the non-volatile resistive memory device, and the switching mechanism itself are discussed.