Scanning carrier current method for in-situ measurement of flying height variation

A novel writing process based in-situ flying height measurement method, sca nning carrier current method, is proposed. An erasure current oscillating i n the frequency range of 200 similar to 800 kHz is injected to the write he ad during the period of interest. Later, its effect on previously written d ata is detected to infer the flying height during the period of interest. T he maximum scanning carrier current method provides a good solution to meas ure flying height variation in a large range during dynamic transient proce ss. When the slider is in steady flying status, a lower scanning carrier cu rrent method can reduce the noise caused by media's MrT fluctuation, whilst a biased scanning carrier current method is suitable to reduce the noise c aused by media's coercivity fluctuation in the flying height testing proces s.