Microwave characterisation of La- and Dy-doped BiFeO3 Thin Films

The dielectric response of La-and Dy-doped BiFeO₃ thin films at microwave frequencies (up to 12 GHz) has been monitored as a function of frequency, dc electric and magnetic fields. Both the real and imaginary parts of the response have been found to be non-monotonic (oscillating) functions of measuring frequency. These oscillations are not particularly sensitive to the dc electric field, however, they are substantially dampened by the magnetic field. This phenomenon is attributed to the presence of a limited number of structural features with a resonance type response. The exact origin of these features is unknown at present.