Analysis of Magnetic Flux Through Magnetic Film With Negative Permeability

This paper clarified that a magnetic film becomes transparent for the magnetic flux when the relative permeability of the magnetic film becomes negative above the intrinsic ferromagnetic resonance frequency. We evaluated the magnetic flux through the magnetic film based on magnetic circuit considering leakage magnetic flux from the magnetic film and demonstrated by the near field measurement using shielded loop coil type magnetic field probe. In this case, we used the coplanar transmission line and amorphous CoZrNb film as a source of the magnetic field and a magnetic film, respectively. As a result, we clarified that the magnetic flux in the magnetic circuit increases when the total reluctance of the magnetic film and leakage magnetic flux path decreases because of a negative reluctance of magnetic film. Thus, the magnetic flux through the magnetic film increases only around this frequency. And the magnetic film behaves as a bandpass filter.