Modeling and Characterization of Smart LSMO Ferromagnetic Thin-Film Tunable Resistance

This paper addresses the potential use of the (La_0.67, Sr_0.33)MnO₃ (LSMO) ferromagnetic thin-film materials as microwave tunable enabling technology. LSMO thin-film materials have a strong interaction between their electrical and magnetic properties that could be translated into innovative tunable microwave components. The knowledge of the electroactive and magnetoactive properties of these materials is essential for modeling and design of novel microwave devices. The activity of these materials can be described by their electro/magnetoresistance and magnetocapacitance. The 400-nm-thick LSMO thin film is formed by the chemical solution deposition. Interdigital capacitor is chosen due to its high sensitivity for tunability and the fact that the metallization and patterning by photolithography are key issues in the fabrication of such structures which are formed by the deposition of metal on a single side of the LSMO thin film. The I-V relation, measured by tuning the bias voltage, is nonlinear and symmetric with respect to the polarity of the applied field. The switching to high resistive state is definite and sharp. Under electrostatic bias field, it is assumed that electric current flowing through narrow low-resistance path induces intense local magnetic field, resulting in the decrease of film resistance. This paper takes a close look in modeling the change of the LSMO resistance in terms of both working frequency and applied bias.