Berlin 2005 – wissenschaftliches Programm
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M: Metallphysik
M 30: Symposium Tomographic Methods in Materials Research
M 30.1: Vortrag
Montag, 7. März 2005, 11:00–11:20, TU H1058
Quantitative Field Determination for Magnetic Recording Heads — •Robert Ferrier1 and Pat Ryan2 — 1Department of Physics and Astronomy, The University of Glasgow, Glasgow G12 8QQ, UK — 2Advanced Transducer Development, Seagate Technology Inc., 7801 Computer Av. - M.S. NRW102, Bloomington MN 55435, USA
The magnetic recording industry is constantly striving to increase the areal density of information storage and currently 170Gbits/inch2 has been demonstrated. Track widths are now approaching 120nm and the high coercivity media employed require writing fields in excess of 0.4T and head flying heights of the order 20nm. Thus to assess the modelling of inductive head writing fields we must measure the field distribution at this distance or closer to the air bearing surface (ABS). The technique employed is electron beam tomography and the input data for the real space back projection method is obtained from orthogonal components of differential phase contrast image intensity obtained using a FEGSTEM instrument. The construction of the recording head combines the inductive writer in combination with a GMR reading head. The magnetic shielding poles for the latter are substantially longer than the width of the writing pole and if shadowing effects due to misalignment of the ABS in the microscope are to be minimised then only a small region (2.0x0.5µm2) around the writing polegap must remain in the original ABS plane. This is achieved by a combination of mechanical polishing, chemical etching and FIB milling. The determination of absolute field distributions for heads with writing pole widths 0.33µm and 0.22µm will be described and the future use of the method will be assessed.