High-Frequency Magnetoimpedance Response of Thin-Film Microstructures Using Coplanar Waveguides

Development of accurate measuring techniques is an important task for the high-frequency materials characterization. The magnetoimpedance (MI) of [Py(170 nm)/Ti(6 nm)]₃/Cu(250 nm)/[Ti(6 nm)/Py(170 nm)]₃ multilayer sandwiched structures is measured using two different high-frequency test fixtures and the results are compared for both cases. Sets of rectangular samples with different lengths and widths are fabricated by photolithography and inserted in test fixtures based either on microstrip or coplanar waveguides (CPWs). Measurements with CPWs ensure higher MI values, since their contribution to the total impedance is lower. Besides, we describe the de-embedding procedure that allows the subtraction of the external impedance brought about by the CPW from the total impedance that is measured using the test fixture. The intrinsic MI ratio of the thin-film structures, obtained by this de-embedding procedure, reaches 550%.