Device of evaluating magnetic read head and method of evaluating magnetic read head

A device of evaluating a magnetic read head having a magnetoresistive element including a magnetically free layer, and a magnetic bias layer that applies a bias magnetic field to the magnetically free layer, comprising:

• a measuring section measuring a ferromagnetic resonance frequency of the magnetically free layer under a condition of applying a predetermined external magnetic field to the magnetically free layer;
• and
• an operation section computing the bias magnetic field according to a conditional equation (1),
• Hb={(2*π*f0/γ)2/Ms}−(Hk+Hm) (1)
• where Hb is the bias magnetic field, f0 is the ferromagnetic resonance frequency of the magnetically free layer, γ is a gyroscope constant, Ms is a saturation magnetic field of the magnetically free layer, Hk is a shape anisotropy magnetic field of the magnetically free layer, and Hm is the external magnetic field applied to the magnetically free layer.