Permeability Measurement of CoFeB Thin Films by Using 2nd Harmonic Signals of PHR Sensor

We measured the permeability of CoFeB thin films by using the second harmonic signals of planner Hall resistance (PHR) sensor in the low frequency range of 10 Hz similar to 50 kHz. The low frequency permeability of CoFeB thin film was compared with the microwave permeability measured by using one-turn coil as well as the real permeability calculated by LLG equation. We confirmed that the low frequency permeability of CoFeB thin film was correspond to the initial permeability of CoFeB thin film. Thus the second harmonic signals of the PHR sensor can be applied to the low frequency permeameter with compact, high resolution and low power consumption.