Microwave characterization of Nd0.67Sr0.33MnO3-x thin films for magnetically tunable filters

We report on the microwave properties of Nd0.67Sr0.33MnO3-x (NSMO) and NSMO /YBa2Cu3O7-x thin film heterostructures. The quality factor (Q) and center frequency of a 13 GHz shielded dielectric cavity resonator, with the film c omprising one surface, were measured as functions of temperature and direct current magnetic field. The Q versus field data was theoretically simulate d using the Landau-Lifschitz-Gilbert dynamic permeability equation thus dem onstrating that the microwave losses are determined by the ferromagnetic pr operties of the films. Our results indicate that the field-dependent permea bility mu(B) of NSMO films holds the potential to create magnetically tunab le microwave devices. (C) 1999 American Institute of Physics. [S0003-6951(9 9)03605-0].