Structure, transition temperature, and magnetoresistance of titanium-doped lanthanum barium manganite epilayers onto STO 001 substrates

摘要

We have developed a thin film structure with a maximum magnetoresistance effect (MRE) at room temperature, which is one of the operating requirements for many applications. It is shown that La_(0.67)Ba_(0.33)Ti_(0.02)Mn_(0.98)O_3 epilayers obtained by pulsed laser deposition onto (001) SrTiO_3 single crystal substrates exhibit the highest MRE, △R/R(H) ≈ 150% or △/R(0) ≈ 60% under 5T, at 300 K, a temperature near to the corresponding Curie temperature (T_C). Both doping with a tiny amount of titanium and induced stress due to lattice mismatch between the thin film and the substrate contribute to a decrease in T_C as compared to the pristine compound and therefore to the decrease in the temperature where the highest MRE is recorded.