Tunability of Ferromagnetic (La,Sr) MnO3 (LSMO) Thin Films for Microwave Applications

Tunability is being driven by a number of very interesting enabling technologies. This work demonstrates the feasibility of ferromagnetic thin film tunability at ambient temperature for radio frequency applications. A 400 nm thick LSMO thin film is formed by the chemical solution deposition (CSD) on the top of indium tin oxide (ITO)/SiO₂/Si heterostructure. Interdigitated capacitor metallization is deposited on LSMO thin film. The resistance of the LSMO based heterostructure varies with bias voltage as a consequence of local ferromagnetic ordering due to transport current induced in the material by an applied field. At zero bias, the low impedance measurement indicates that the heterostructure exhibits a lossy capacitance. Under the applied field the heterostructure becomes inductive and the losses are reduced.