Memory Effect in Thin Thermocycling-modified La0.67Ca0.33MnO3 Films

Nonhomogeneous thin La0.67Ca0.33MnO3 films, having T-m in 180 K - 200 K temperature range, were thermocycled between 80 K and 210 K using liquid nitrogen. After the thermocycling it was confirmed formation of highly resistive state with additional low temperature peak of resistance with maximum at 115 K when measuring R-T plots. Measurements of electroresistive effect in this state using low dc of different values and performed in cooling run reveal discontinuities of R-T plots. It is proposed formation of two different high resistive states: at low temperatures and at vicinity of T-m. The discontinuities disclose switching between these two states initiated by substrate-induced long-range strain and by manifestation of memory effect. This interpretation of experimental results explains appearing of low temperature peak based on influence of the long-range strains on formation of high resistive interlayers in the film during the thermocycling. We argue that the interlayers acquire memory properties after being modified by martensitic-type transformations.