Pulsed laser deposition of (Sr_1-xCa_x)RuO_3 and Sr(Ru_1-xTi_x)O_3 thin films by sequential multilayer process

摘要

We report on the growth and properties of (Sr_1-xCa_x)RuO_3 and Sr(Ru_1-xTi_x)O_3 thin films obtained by pulsed laser deposition. A sequential deposition of sub-monolayers from SrTiO_3 and CaRuO_3 end members has been successfully used to substitute Ca- and Ti- in the SrRuO_3 perovskite structure. Magnetization measuremdents as well as transport properties exhibit very different behaivor for each type of substitution. In the case of Ca- substituted smaples, the resistivity remains metallic and is consistent with the expected behavior for intermediate compositions. A progressive reduction of the Curie temperature with higher doping is reported. In the case of Ti- substituted samples, we observe a stronger reduction of the Curie temperature and remanent magnetization with increasing Ti substitution. Resistivity as a function of temperature shows a crossover from metallic to semiconducting behavior with variable range hopping process for a high level of Ti doping and pints out the clear differences between the two substitutions sites. In both cases, the observed reduction of the magnetization with increasing doping concentration can be well described by assuming a random distribution of substituted sites in the perovskite structure.