Magnetic proximity effect in Pr0.5Ca0.5MnO3/La0.7Sr0.3MnO3 bilayered films

Анотація

The magnetotransport properties of Pr_0.5Ca_0.5MnO₃/La_0.7Sr_0.3MnO₃ bilayer, and Pr_0.5Ca_0.5MnO₃ and La_0.7Sr_0.3MnO₃ films, deposited on LaAlO ₃ (001) substrate by pulse laser deposition have been investigated. The x-ray diffraction and high-resolution electron-microscopy analysis reveals that lattice parameters for the constituent sublayers in the bilayer are very close to that for the individual films. It was found that a ferromagnetic transition in the La_0.7Sr_0.3MnO₃ sublayer significantly modifies the magnetotransport properties of the Pr_0.5Ca_0.5MnO₃ constituent sublayer, owing to occurrence of a magnetic proximity effect. The main evidences for this effect are an appearance of the exchange bias interaction between the constituent sublayers; a localized-to-itinerant crossover in the system of polarized electrons, which results in formation of the Griffiths-like ferromagnetic state; and an unusual polaron transport of carriers. The experimental results have been analyzed within the framework of modern theoretical approaches.