High-frequency properties of stray fields emanating from hard disk writer poles up to 2 GHz

Using high-frequency magnetic force microscopy (HF-MFM), we investigate the stray fields emanating from hard disk writer poles. An amplitude-modulated high-frequency current is sent to the writer coil, and the resulting stray fields are imaged by HF-MFM, employing carrier frequencies up to 2 GHz. This advance is possible due to ferrite-coated MFM cantilevers. We observe that, as a function of frequency, the emanating field is forming two peaks around the gap area, and the maximum field is shifting from the centre position in the gap towards one side of the writer pole.