Modeling of colossal magnetoresistance in La_(0.67)Ca_(0.33)MnO_3/Pr_(0.67)Ca_(0.33)MnO_3 superlattices: Comparison with individual (La_(1-y)Pr_y)_(0.67)Ca_(0.33)MnO_3 films

摘要

Colossal magnetoresistance (CMR) and nm-scale electronic inhomogeneity close to the first order phase transition in perovskite manganites, e.g., (La_(1-y)Pr_y)_(0.67)Ca_(0.33)MnO_3 still remain a puzzling phenomenon. We experimentally model a metal-insulator phase coexistence by growing a short period (LCMO_n/PCMO_n)_m superlattices (SLs) with the same thickness for both components. CMR effect was studied as a function of the individual layer thickness n = 2-8 and then compared with chemically homogeneous (La_(1-y)Pr_y)_(0.67)Ca_(0.33)MnO_3 LPCMO films. We show that SLs can be superimposed in the phase diagram of LPCMO. The results also point out the importance of the nm-scale electronic rather than chemical separation for realization of the CMR effect as well as limits the lowest boundary for the thickness of an individual manganite material to n ～ 4u.c.