IEEE Santa Clara Valley Section  

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IEEE Magnetics Society
Santa Clara Valley Chapter
Meeting Presentation Summary


Tuesday, September 18th, 2012

Western Digital, 1710 Automation Parkway, San Jose, CA
Directions and Map
Cookies, Conversation & Pizza too at 7:00 P.M.
Presentation at 7:30 P.M.

Microwave Assisted Magnetic Recording

Dr Mike Mallary
Western Digital Corp.


    Perpendicular Magnetic Recording, PMR, will soon reach its superparamagnetic limit. Shingling the write process will allow significant increases in areal density but with significant system complexity and performance issues in some applications. At this time, Heat Assisted Magnetic Recording and Bit Patterned Media are the primary candidates to replace PMR. However there are significant concerns associated with these approaches. The economics of BPM are a considerable barrier by most estimates. The high temperatures of HAMR are a serious reliability concern and perfecting FePt media is very challenging. Even though MAMR is not expected to extend areal density as far as these other alternatives, its implementation would require smaller changes from PMR. Therefore MAMR may be able to sustain areal density growth while these alternate technologies are being perfected. But can MAMR be made to work well enough?
    At this time there are no published demonstrations of MAMR at high densities. However, there are a number of reported observations of partial and full switching of PMR like media with moderate DC fields assisted by rf fields from micro-loops or a Spin Torque Oscillator (STO) These results will be discussed along with the results of simulations and experiments by the author. Micromagnetic simulations of the MAMR write process indicate that MAMR could approximately double recording density beyond the limits of PMR on optimized media. The system studied was that of a STO in the write gap of a wide track shielded pole PMR like head as originally proposed and patented by Prof. Jimmy Zhu of the Data Storage System Center at Carnegie Mellon University. Micromagnetic simulations of the MAMR write process, M-H loops with rf fields, Ferromagnetic Resonance of media, and STOs will be presented. In addition, some experimental results on media FMR and STO performance will be discussed.

Copy Of Presentation


Photo of Dr Mike Mallary     Dr Mike Mallary received the S.B. degree in physics from the Massachusetts Institute of Technology, Cambridge, in 1966, and the Ph.D. degree in Experimental High Energy Physic from the California Institute of Technology, in 1971.
    He was a post doctoral fellow at the Rutherford Laboratory for from 1972-1974 and an Assistant Professor of physics at Northeastern University from 1974-1978. There he participated in an experiment at Fermi Laboratory that produced early evidence for the fifth quark using a 300 ton solid iron magnet. From 1978 to 1980 he worked at the Magnetic Corporation of America designing large superconducting magnetics.
    In 1980 he joined the Digital Equipment Corporations effort to produce thin film heads for disk drive recording as a head modeler and designer. Here he invented the Shielded Pole perpendicular recording head which has demonstrated superior performance over the conventional monopole head and is presently in all shipped disk drives. He also invented the Diamond inductive head which doubles the effective number of turns and contributed to the theory of flux conduction in thin film heads.
    Through a series of acquisitions beginning in 1992, Dr Mallary worked for Quantum, MKQC, Maxtor, and Seagate. He is presently a Senior Technologist with Western Digital Corporation. He has authored and co-authored 92 issued U.S. patents (140 total) and 52 publications. He is an IEEE Fellow and was an IEEE Distinguished Lecturer in 2009.



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