Peculiar Electrical and Magnetic Properties of La(Ba)MnO₃ Thin Films

Abstract

In this article it is reviewed on enigmatic electrical and magnetic properties of La(Ba)MnO 3 thin films, useful for tunable microwave filters. As-grown films have well separated insulating to metallic (T p ) and paramagnetic to ferromagnetic (T c ) transition temperatures, which can be understood from the phase separation model. The film shows negative magnetoresistance (MR) caused by normal double exchange coupling effect, and positive MR which is interpreted by a magnetostriction effect. The phase separation is caused by crystal strain in the film. By annealing these two temperatures, T p and T c , become more separated, implying a size reduction of ferromagnetic grains. The phase separation scenario can be confirmed by ferromagnetic resonance (FMR) showing doublet signals. The FMR indicates anisotropic phase transition which supports the magnetostriction model. Moreover, the narrow FMR signals suggest high spin ordering and good crystallinity.

Current-dependent positive magnetoresistance in La0.8Ba0.2MnO3 ultrathin films*

“…At 65 K and 40 K below T P , the thinner film displays the PMR effect, which has rarely been observed in doped manganites. Endo et al reported a similar PMR behavior in La 0.7 Ba 0.3 MnO 3 films epitaxially grown on LaAlO 3 substrates by the ion beam sputtering technique, [31] but its dependence on the test current was not mentioned. We note that some authors have reported a giant (volume) magnetostrictive effect in doped manganites with a coefficient of ∼ −10 −4 , [32][33][34][35] while it is around 10 −5 in conventional ferromagnetic materials.…”

ESR Study of (La,Ba)MnO3/ZnO Nanostructure for Resistive Switching Device

“…Due to a number of competitive interactions, the ground state of bulk and thin films of La 1- x Me x MnO 3 is often phase separated and usually characterized by a coexistence of highly conductive ferromagnetic (FM) phase and poorly conductive paramagnetic (PM) or charge-ordered phases [2]. Such complexity of the properties of perovskite manganites has become the point of attraction for a vast number of researchers around the world [2, 5, 6]. It is expected that this class of materials will create the foundation for various applications, such as low-field magnetoresistance sensors, resistive switching devices, and others [6, 7].…”

“…Such complexity of the properties of perovskite manganites has become the point of attraction for a vast number of researchers around the world [2, 5, 6]. It is expected that this class of materials will create the foundation for various applications, such as low-field magnetoresistance sensors, resistive switching devices, and others [6, 7]. …”