Alternating Magnetic Force Microscopy: Effect of Si doping on the temporal performance degradation of amorphous FeCoB magnetic tips

•FeCoB-based tips provide sufficient performance to image 500 kfci magnetic media.•A-MFM provides 5 nm spatial resolution and gives higher sensitivity than MFM.•Si doping of FeCoB provides film oxidation and loss of imaging performance with time.•Si free FeCoB film demonstrates effective surface passivation with oxide layer.