Dielectric spectra in cation deficient (LaMn)_(1-γ)O_3

摘要

Lanthanum manganites doped with divalent alkaline earth ions are studied due to the giant magnetoresistance (GMR) phenomenon [1-5]. Usually, these materials are considered as homogeneous from the viewpoint of magnetic and electrical properties, even in the case of a slight doping [1-8]. It is interesting to note that ferromagnetism could be induced by simply creating cation vacancies at the La site even in the absence of any divalent ion substitution [9-15]. LaMnO_(3 + δ) is the only compound of LaMO_3 (M = 3d transition metal ions) series that shows noteworthy oxygen excess. The oxygen excess δ, which cannot be accommodated interstitially in the lattice, results in equal amount of La and Mn vacancies, being 2 * 100 δ the corresponding percentage of Mn~(4+).